2012-02-18 Djibouti Africa, US Air Force U-28 Final Accident Report

UNITED STATES AIR FORCE
AIRCRAFT ACCIDENT INVESTIGATION
BOARD REPORT
U-28A, TIN 07-0736
HURLBURT FIELD, FLORIDA
LOCATION: NEAR CAMP LEMONNIER, DJIBOUTI
DATE OF ACCIDENT: 18 FEBRUARY 2012
BOARD PRESIDENT: BRIG GEN TIMOHTY LEAHY
Conducted lAW AFI 51-503, Aerospace Accident Investigations
INTENTIONALLY
LEFT
BLANK
EXECUTIVE SUMMARY
AIRCRAFT ACCIDENT INVESTIGATION
U-28A, TIN 07-0736
5 NM SOUTHWEST OF AMBOULI INTERNATIONAL AIRPORT, DJIBOUTI
18 FEBRUARY 2012
On 18 February 2012, at approximately 1918 local time (L), a United States Air Force U-28A
aircraft, tail number 07-0736, crashed five nautical miles (NM) southwest of Ambouli
International Airport, Djibouti. This aircraft was assigned to the 34th Special Operations
Squadron, lst Special Operations Wing, Hurlburt Field, FL, and deployed to the 34th
Expeditionary Special Operations Squadron, Camp Lemonnier, Djibouti. The aircraft was
destroyed and all four aircrew members died instantly upon impact.
The mishap aircraft (MA) departed Ambouli International Airport, Djibouti at 13571, to
accomplish a combat mission in support of a Combined Joint Task Force. The MA proceeded to
the area of responsibility (AOR), completed its mission in the AOR and returned back to
Djiboutian airspace at 1852L arriving overhead the airfield at 1910L to begin a systems check.
The MA proceeded south of the airfield at 10,000 feet (ft) Mean Sea Level (MSL) for 10 NM
then turned to the North towards the airfield, accomplished a systems check and requested entry
into the pattern at Ambouli International Airport. This request was denied due to other traffic,
and the MA was directed to proceed to the west and descend by Air Traffic Control (ATC). The
MA began a left descending tum to the west and was directed by A TC to report final. The
mishap crew (MC) reported they were passing through 4,000 ft MSL and would report when
established on final approach. The MA, continuing to descend, initiated a right turn then
reversed the turn entering a left turn while continually and smoothly increasing bank angle until
reaching 55 degrees prior to impact. Additionally, the MA continued to steadily increase the
descent rate until reaching 11,752 ft per minute prior to impact. The MC received aural "Sink
Rate" and "Pull Up" aletis with no apparent corrective action taken. The MA impacted the
ground at approximately 19181, 5 NM southwest of Ambouli International Airport, Djibouti.
The MC never lost control of the aircraft; there are no indications of mechanical malfunction;
and there are no indications the crew took any actions to control or arrest the descent rate and
nose down attitude. The evidence demonstrates that the MC did not recognize the position of the
aircraft and, as a result, failed to take appropriate corrective actions. The only plausible reason
for the MC not recognizing the situation or reacting to aural alerts is the cognitive disconnect
associated with spatial disorientation. The Board President found that the clear and convincing
evidence indicated the cause of the mishap was unrecognized spatial disorientation.
Additionally, the Board President found by a preponderance of the evidence that failing to crosscheck
and ignoring the "Sink Rate" caution substantially contributed to the mishap.
Under 10 U.S.C. § 2254(d), the opinion ofthe accident investigator as to the cause of or the factors
contributing to, the accident set forth in the accident investigation report, if any, may not be considered
as evidence in any civil or criminal proceeding arising from the accident, nor may such information be
considered an admission of liability of the United States or by any person referred to in those conclusions
or statements.
INTENTIONALLY
LEFT
BLANK
SUMMARY OF FACTS AND STATEMENT OF OPINION
U-28A, TIN 07-0736
18 FEBRUARY 2012
Table of Contents
SUMMARY OF FACTS ................................................................................................................ 6
1. AUTHORITY AND PURPOSE ............................................................................................. 6
a. Authority .............................................................................................................................. 6
b. Purpose .................................................................................................................................. 6
2. ACCIDENT SUMMARY ....................................................................................................... 6
3. BACKGROUND .................................................................................................................... 7
a. 1st Special Operations Wing ................................................................................................ 7
b. 1st Special Operations Group .............................................................................................. 7
c. 34th Special Operations Squadron ....................................................................................... 7
d. 319th Special Operations Squadron ..................................................................................... 8
e. 25th Intelligence Squadron ................................................................................ : ................. 8
f. U-28A .................................................................................................................................. 8
4. SEQUENCE OF EVENTS ..................................................................................................... 9
a. Mission ................................................................................................................................. 9
b. Planning ............................................................................................................................... 9
c. Preflight. ...................... ; ........................................................................................................ 9
d. Summary of Accident .......................................................................................................... 9
e. Impact ................................................................................................................................ 11
f. Egress and Aircrew Flight Equipment ............................................................................... 12
g. Search and Rescue ............................................................................................................. 12
h. Recovery ·of Remains ......................................................................................................... 13
5. MAINTENANCE ................................................................................................................. 13
a. Forms Documentation ........................................................................................................ 13
(1) Discrepancy Records .................................................................................................. 13
(2) Aircraft Flight Hours/Engine Hours ........................................................................... 14
b. Inspections ......................................................................................................................... 14
(1) Preflight/Postflight ...................................................................................................... 14
(2) Progressive Inspection Program ................................................................................. 15
c. Maintenance Procedures .................................................................................................... 15
U-28A, T/N07-0736, 18 February 2012
d. Maintenance Personnel and Supervision ........................................................................... 16
e. Fuel and Oil Inspection Analyses ...................................................................................... 16
(1) Fuel ............................................................................................................................. 16
(2) Oil ............................................................................................................................... 16
(3) Unscheduled Maintenance ................................................................................. : ........ 17
6. AIRFRAME SYSTEMS ........................................................................................................ 17
a. Structures and Systems ...................................................................................................... 17
(1) Mishap Engine ............................................................................................................ 17
(2) Enhanced Ground Proximity Warning System ........................................................... 18
(3) Attitude Indicator ........................................................................................................ 18
( 4) Flight Control Trim Tabs ............................................................................................ 18
(5) Flaps ............................................................................................................................ 19
( 6) Airspeed Indicator ........................................................................................................ 19
(7) Emergency Locator Transmitter ................................................................................. 20
(8) Other Evaluated Components ................................................................................ ~ .... 20
7. WEATHER ........................................................................................................................... 20
·a. Forecast Weather ............................................................................................................... 20
b. Observed Weather .............................................................................................................. 20
c. Space Environment ............................................................................................................ 21
d. Operations .......................................................................................................................... 21
8. CREW QUALIFICATIONS ................................................................................................. 21
a. Mishap Pilot ....................................................................................................................... 21
b. Mishap Copilot. .................................................................................................................. 21
c. Mishap Operator 1 ............................................................................................................. 22
d. Mishap Operator 2 ............................................................................................................. 22
9. MEDICAL ............................................................................................................................ 23
a. Qualifications ..................................................................................................................... 23
b. Health ................................................................................................................................. 24
c. Pathology ........................................................................................................................... 24
d. Lifestyle ............................................................................................................................. 24
e. Crew Rest and Crew Duty Time ........................................................................................ 24
10. OPERATIONS AND SUPERVISION .............................................................................. 25
a. Operations .......................................................................................................................... 25
b. Supervision ........................................................................................................................ 26
U-28A, TIN 07-0736, 18 February 2012
ii
11. HUMAN FACTORS ANALYSIS ..................................................................................... 26
a. Overview ............................................................................................................................ 26
b. PC508 Spatial Disorientation (Type 1) Unrecognized ...................................................... 27
c. PC503 Illusion- Visual ..................................................................................................... 27
d. PC502 Illusion- Vestibular ............................................................................................... 27
e. AE205 Caution/Warning- Ignored ................................................................................... 28
f. PC102 Channelized Attention ............................................................................................ 28
g. PC307 Fatigue- Physiological/Mental ............................................................................. 28
12. FLIGHT SIMULATION ................................................................................................... 29
a. Flight Si1nulator ................................................................................................................. 29
b. MA Profile ......................................................................................................................... 29
c. Spatial Disorientation ......................................................................................................... 31
13. GOVERNING DIRECTIVES AND PUBLICATIONS .................................................... 33
a. Primary Operations Directives and Publications ............................................................... 33
b. Maintenance Directives and Publications .......................................................................... 33
c. Medical Directives and Publications ................................................................................. 33
d. Known or Suspected Deviations from Directives or Publications ..................................... 33
14. ADDITIONAL AREAS OF CONCERN .......................................................................... 34
15. SIGNATURE AND DATE ................................................................................................ 34
STATEMENT OF OPINION ....................................................................................................... 35
1. OPINION SUMMARY ........................................................................................................ 35
2. DISCUSSION OF OPINION ............................................................................................... 35
3. CONCLUSION ..................................................................................................................... 38
INDEX OF TABS ......................................................................................................................... 39
U-28A, TIN 07-0736, 18 February 2012
iii
COMMONLY USED ACRONYMS & ABBREVIATIONS
A&P Airframe and Powerplant IF Initial Approach Fix
AC Aircraft Commander ILS Instrument Landing System
AD Airworthiness Directives IS Intelligence Squadron
ADI Attitude Display Indicator ISB Interim Safety Board
ADO Assistant Director of Operations ISNS Inertial Satellite Navigation System
AFB Air Force Base ISR Intelligence, Surveillance, and Reconnaissance
AFE Aircrew Flight Equipment JOC Joint Operations Center
AFI Air Force Instruction JSOAD Joint Special Operations Air Detachment
AFSOC Air Force Special Operations Command KIA Killed in Action
AGL Above Ground Level KIAS Knots Indicated Airspeed
AlB Accident Investigation Board L Local Time
AIMWTS Aeromedical Information Management LA Legal Advisor
Waiver Tracking System M3 Modular Maintenance Management
AIS Advanced Instrument School MA Mishap Aircraft
ALZ Assault Landing Zone MC Mishap Crew
AOA Angle of Attack MCP Mishap Co-Pilot
AOR Area of Responsibility MFD Multifunction Display
ATC Air Traffic Control Ml Michigan
ATO Air Tasking Order MM Medical Member
BFT Blue Force Tracker MOPl Mishap Operator # 1
BP Board President MOP2 Mishap Operator #2
BR Board Recorder MP Mishap Pilot
CAMS Core Automated Maintenance System MQF Master Question File
CAWS Central Advisory and Warning Ssytem MS Mishap Sortie
cc Commander MSL Mean Sea Level
CDI Course Direction Indicator MXM Maintenance Member
CLU Containerized Living Unit NATO North Atlantic Treaty Organization
CP Command Post NCIS Navy Criminal Investigative Service
cso Combat Systems Officer NM Nautical Miles
DC District of Columbia NOT AM Notices to Airmen
DE Delaware NSAv Non-standard Aviation
Det Detachment NTSB National Transportation Safety Board
DME Distance Measuring Equipment NVG Night Vision Goggles
DO Director of Operations OBS Omni Bearing Selector
DoD Department of Defense OH Ohio
EGPWS Enhanced Ground Proximity Warning 01 Operating Instruction
System OP Operator
ELT Emergency Locater Transmitter ORM Operational Risk Management
EP Emergency Procedure OSI Office of Special Investigations
ESOS Expeditionary Special Operations Squadron PAE Pacific Architects and Engineers
FAA
FCIF
FL
FLIR
FMS
fpm
ft
Gen
GPS
HFACS
HSI
lA
Federal Aviation Administration PCL
Flight Crew Information File PERSTEMPO
Florida PHA
Forward Looking Infrared PJ
Flight Management System PM
Feet Per Minute PME
Feet PMEL
Generator
Global Positioning System rad-alt
Human Factors Analysis and SA
Classification System SAF
Horizontal Situation Indicator SAY
Inspection Authorized SITREP
U-28A, TIN 07-0736, 18 February 2012
iv
Power Control Lever
Personnel Tempo
Preventative Health Assessment
Pararescue Jumper
Pilot Member
Professional Military Education
Precision Measurement Equipment
Laboratory
Radar Altimeter
Situational Awareness
Secretary of the Air Force
Staff Assistance Visit
Situational Report
SNC
SOC OM
SOP
SOP
SOG
sos
soss
sow
TIN
TCAS
TCN
TF
TMO
Sierra Nevada Corporation
Special Operations Command
Special Operations Forces
Standard Operating Procedures
Special Operations Group
Special Operations Squadron
Special Operations Support Squadron
Special Operations Wing
Tail Number
Traffic Collision A voidance System
Third Country National
Task Force
Traffic Management Office
TO
TOC
TSO
TV
UAV
USAF
v
VFR
VOR
VVI
WA
wv
z
Technical Order
Tactical Operations Center
Tactical Systems Officer
Television
Unmanned Aerial Vehicle
United States Air Force
Volume
Visual Flight Rules
Visual Operating Restriction
Vertical Velocity Indicator
Washington
West Virginia
Zulu Time
The above list was compiled from the Executive Summary, Summary of Facts, the Statement of
Opinion, the Index of Tabs, and witness testimony (Tab V).
U-28A, TIN07-0736, 18 February 2012
v
SUMMARY OF FACTS
1. AUTHORITY AND PURPOSE
a. Authority
On 22 February 2012, Major General O.G. Mannon, Vice Commander, Air Force Special
Operations Command (AFSOC), convened an Accident Investigation Board (AlB) in accordance
with Air Force Instruction (AFI) 51-503, Aerospace Accident Investigations, to investigate the 18
February 2012 mishap involving U-28A aircraft, tail number (TIN) 07-0736, which crashed five
miles southwest of Djibouti International Airport, Djibouti (Tabs J-88; N-11; Y-3). Brigadier
General Timothy J. Leahy, United States Special Operations Command 17/9, MacDill Air Force
Base (AFB), FL, was appointed AlB President (BP). A Pilot Member (PM), Maintenance
Member (MXM), Medical Member (MM), Legal Advisor (LA), and Recorder (BR) were
appointed to the AlB (Tab Y-3, -5). This investigation was conducted at Hurlburt Field, FL from
1 May 2012 through 18 May 2012 and 5 June 2012 through 15 June 2012.
b. Purpose
This is a legal investigation convened to inquire into the facts surrounding the aircraft or
aerospace accident, to prepare a publicly-releasable report, and to gather and preserve all
available evidence for use in litigation, claims, disciplinary actions, administrative proceedings,
and for other purposes.
2. ACCIDENT SUMMARY
At 1357 local time (L), Camp Lemonnier, Djibouti, the mishap crew (MC) departed aboard the
mishap aircraft (MA), a U-28A, TIN 07-0736, on a mission in support of a Combined Joint Task
Force. (Tabs M-19; V-9.6) The MA was designated as Ratchet 33 for the mishap sortie (MS).
(Tab K-3, -5) The MA departed uneventfully. (Tab EE-7) The MC completed their mission in
their Area of Responsibility (AOR) and returned to Djiboutian airspace at 18521. (Tab M-19)
The MA approached the airfield from the South at 10,000 feet (ft) mean sea level (MSL) for
systems checks. (Tabs N-6; JJ-5) The MC requested a descent for the right base, a right turn to
final for runway 09, but the Ambouli control tower instead cleared the MC to descend west of
the airfield due to traffic. (Tab N-6 to -7) The MC acknowledged and said that they would report
for a left base, a left turn to final. (Tab N -7) At 1917L, the control tower told the MC to report
final for runway 09, and the MC responded with "Ratchet 33 passing 4,000 feet in the descent
west of the field, we'll report final." (Tab N-7) At 1918L, the MA entered into a steadily
increasing left bank, eventually reaching 55 degrees of left bank. (Tab JJ-9) The descent rate
increased from 2,985 feet per minute (fpm) to 11,752 fpm. (Tab JJ-9) Approximately seven
seconds prior to impact, the Enhanced Ground Proximity Warning System (EGPWS) emitted an
aural warning to the MC of "Sink Rate, Sink Rate." (Tab JJ-9) Three seconds later, the EGPWS
instructed the MC to "Pull up, Pull up." (Tab JJ-9) The MA impacted the ground approximately
four seconds later at North 11 o 31.61' East 043° 04.41 ', an uninhabited area approximately 5
miles southwest of Ambouli International Airport. (Tabs JJ-9; N-11) All four crewmembers
were killed on impact. (Tab X-3)
U-28A, TIN 07-0736, 18 February 2012
6
3. BACKGROUND
a. 1st Special Operations Wing
The 1st Special Operations Wing (1 SOW) at Hurlburt Field, FL, is one
of two Air Force active duty Special Operations wings and falls under
AFSOC. The 1 SOW mission focus is unconventional warfare, counterterrorism,
combat search and rescue, personnel recovery, psychological
operations, aviation assistance to developing nations, "deep battlefield"
resupply, interdiction and close air support. The wing has units located
at Hurlburt Field, FL and Eglin Air Force Base, FL. (Tab FF-15)
The wing's core missions include aerospace surface interface, agile combat support, combat
aviation advisory operations, information operations, personnel recovery/recovery operations,
precision aerospace fires, psychological operations dissemination, specialized aerospace mobility
and specialized aerial refueling. (Tab FF-15)
The 1 SOW also serves as a pivotal component of AFSOC's ability to provide and conduct
special operations missions ranging from precision application of firepower to infiltration,
exfiltration, resupply, and refueling of special operations force operational elements. In addition,
the 1. SOW brings distinctive intelligence capabilities to the fight, including intelligence,
surveillance and reconnaissance contributions, predictive analysis, and targeting expertise to
joint special operations forces and combat search and rescue operations. (Tab FF-15)
b. 1st Special Operations Group
The 1st Special Operations Group (1 SOG), located at Hurlburt Field,
FL, is one of four groups assigned to the .1 SOW. The group plans,
prepares, and executes special operations, foreign internal defense, and
security assistance worldwide in support of theater commanders. The
1 SOG also provides aircraft and instructors for the Air Force Special
Operations Training Center school for the AC-130H/U Gunship, MC-
130E/H Combat Talon 1111, and U-28 Pilatus qualification. (Tab FF-13)
In order to accomplish its special operations mission, the group employs more than 70 aircraft to
provide day or night, all-weather access to hostile and/or denied airspace. More than 1,400
people are assigned to the group. There are ten squadrons within the group with one at a
geographically separated location. (Tab FF-13)
c. 34th Special Operations Squadron
The 34th Special Operations Squadron was activated at Hurlburt Field, FL
on 9 April 201 0 to conduct special operations mission. They operate the
U-28A aircraft, a variation ofthe Pilatus PC-12. (Tab FF-5)
U-28A, TIN 07-0736, 18 February 2012
7
d. 319th Special Operations Squadron
The 319th Special Operations Squadron (319 SOS) mission is to provide
intra-theater support for special operations forces. To accomplish the
mission, they use the U-28A, a variation of the Pilatus PC-12. (Tab FF-
7)
e. 25th Intelligence Squadron
f. U-28A
The 25th Intelligence Squadron (25 IS) is a selectively-manned and
uniquely tasked unit, chartered to provide specialized intelligence across
the spectrum of conflict. Squadron personnel are qualified to operate as
aircrew on board every combat aircraft within the AFSOC inventory.
By integrating all-source intelligence and electronic combat capability
for special operations forces (SOF), the 25 IS has made Air Force
Intelligence, Surveillance, Reconnaissance (ISR) Agency resources
integral to SOF mission planning, rehearsal, and execution--truly
highlighting AFSOC's motto: "One Team, One Fight." (Tab FF-9)
The U-28A is part of AFSOC's Non-Standard Aviation (NSAv) fleet, and is operated by the 319
SOS and 34 SOS. Training is conducted by the 5 SOS and 19 SOS; all squadrons are located at
Hurlburt Field, FL. The rapidly changing and diverse United States Special Operations
Command (SOCOM) mission requirements generated a need for small numbers of mission
specific aircraft which were procured rapidly to address specific mission needs. The NSA v fleet
is a general program term and encompasses several light and medium aircraft performing utility
missions for SOCOM. Overall, the NSAv mobility fleet untethers SOF from robust
infrastructures, extended timelines and allows freedom of movement. (Tab FF-3)
The U-28A provides a manned fixed wing, on-call/surge capability for Improved Tactical
Airborne ISR in support of SOF. (Tab FF-3)
The U-28A is a modified single engine Pilatus PC-12 that operates worldwide. The initial block
ofU-28 aircraft were procured and modified for use in Operations ENDURING FREEDOM and
IRAQI FREEDOM. The U-28A fleet evolved from commercially available aircraft that were
purchased and then modified with communications gear, aircraft survivability equipment,
electro-optical sensors, and advanced navigation systems. The advanced radio-communications
suite is capable of establishing Department of Defense (DoD)/North Atlantic Treaty
Organization (NATO) data-links, full motion video, data, and voice communications. The
U-28A has outstanding reliability and performance, and is certified to operate from short and
semi-prepared airfields. (Tab FF-3)
All U-28A aircraft are maintained through contractor logistics support. (Tab FF-3)
U-28A, TIN 07-0736, 18 February 2012
8
4. SEQUENCE OF EVENTS
a. Mission
The MS was a combat sortie tasked in support of a Combined Joint Task Force. (Tab V-9.6) The
MC consisted of a mishap aircraft commander (MP), copilot (MCP), operator 1 (MOP1), and
operator 2 (MOP2).
b. Planning
The MS was planned the day prior by the Duty Desk Officer. (Tab V-9.5) The takeoff and
landing data and the international flight plan (DD Form 1801) were all complete and accurate.
(Tab K-3, -9) The Form 1801 was filed with Base Operations on 17 February 2012 for the MS.
(Tab V-2.3) The Flight authorization orders, weather, and Notices to Airmen (NOTAM) were
all completed by the Duty Desk Officer prior to the MC showing up for their flight. (Tab V-2.3)
The MC was handed an aircraft weight and balance that was incorrect and showed the aircraft to
be aft of the allowable center of gravity. (Tab K -7) This weight and balance was corrected after
the mishap. (Tab V -9 .5) The weight and balance given to the crew did not account for the life
raft being moved forward which, in tum, moved the center of gravity into a flyable range. (Tab
K -7) This corrected weight and balance was done after the mishap by the Duty Desk. (Tab V-
9.5) The operational risk management (ORM) was filled out but did not reflect the required
extra level of ORM due to the low moon illumination. (Tabs K-11 to -12, BB-3 to -4) It is
unknown if the low moon illumination was briefed during the crew brief.
c. Preflight
The MC arrived at 1200L to the Tactical Operations Center (TOC) to look over the flight plan
and receive the intelligence brief. (Tab EE-5) The MC briefed with the crew of Ratchet 26 on
the emergency procedure of the day, the troubleshooting procedure of the day, and both crews
received the intelligence brief together. (Tab EE-5) After those briefs, the crews separated and
the MC executed the crew brief for the MS in a separate room. (Tab EE-6) The MC stepped to
the MA at approximately 13 OOL, started the engine, taxied, and took off at 13 57L. (Tab M -19)
d. Summary of Accident
The MA departed the airfield, climbed to altitude, and proceeded into the AOR uneventfully
(Tab EE-7). The MC completed the assigned mission uneventfully and returned to Djiboutian
airspace at 1852L. (Tab M-19) The MA arrived over the airfield at 10,000 ft MSL and was
given permission by the Ambouli control tower to proceed to the South of the field for systems
checks. (Tab N-6) The control tower told the MC to remain at 10,000 feet MSL due to traffic
leaving the airfield. (Tab N-6) The MA proceeded south of the airfield at 10,000 feet MSL and
turned back to a North heading to initiate the systems check. (Tab M-4) After the completion of
the systems check, the MC requested a descent for the right base, a right turn to final for runway
09, but the Ambouli control tower instead cleared the MC to descend west of the airfield due to
traffic. (Tab N-6 to -7) The MC acknowledged and said that they would report for a left base, a
left turn to final. (Tab N-7)
U-28A, TIN 07-0736, 18 February 2012
9
According to testimony, the normal procedure for descending from 10,000 ft MSL to enter into
the visual pattern at Ambouli at night and on Night Vision Goggles (NVGs) is to slow down
below 177 knots indicated air speed (KIAS), lower the gear, then descend ensuring to not exceed
236 KIAS at 15 to 20 degrees nose low attitude. (Tab V-2.9 to -2.11, V-3.10 to -3.11) According
to the radar tracks from the approach control radar at Ambouli, the MA was using this normal
procedure to descend to the west. (Tab M -4 to -18) According to testimony; the MP would
normally perform this maneuver on NVGs. (Tab V-2.9 to -2.11, V-3.10 to -3.11) The radar track
shows a left descending turn with an initial descent rate of 6,000 fpm which slows to 2,400 fpm
until an altitude of 6,300 ft MSL where the descent rate begins to climb to 8,400 fpm until
leveling off at 4,400 ft MSL. (Tab M-5 to -13) The MA is level at 4,400 ft MSL for
approximately 5 seconds until the MA begins another descent starting at 8,400 fpm. At 1917L,
the MA is told by the control tower to report final for runway 09, and the MC responds with
"Ratchet 33 passing 4,000 feet in the descent west of the field, we'll report final." (Tab N-7)
At 1917:52, and at 2,972 ft MSL, the on board EGPWS shows a descent of 2,443 fpm and a 24.5
degree right turn with 195 knots ground speed. (Tab JJ-9) The EGPWS shows data every second
and shows the MA in a relatively constant descent, a decreasing right turn, and decreasing
ground speed for ten seconds. (Tab JJ-9) At 1918:04L, the MA enters into a steadily increasing
left bank eventually reaching 55 degrees, while increasing the descent rate from 2,985 fpm to
11,752 fpm, and decreasing the ground speed from182 knots to 165 knots. (Tab JJ-9)
Approximately seven seconds prior to impact, the EGPWS emitted an aural warning to the MC
of "Sink Rate, Sink Rate," advising the MC that there was an excessive descent rate occurring.
(Tab JJ-9) This warning occurred at 1,800 ft MSL, approximately 1,600 ft above ground level
(AGL), with an approximate descent rate of 5,400 fpm. (Tab JJ-9) Another warning was issued
by the EGPWS approximately four seconds prior to impact that instructed the MC to "Pull up,.
Pull up." (Tab JJ-9) This warning occurred at 1,302 ft MSL, approximately 1,102 ft AGL, with a
8,000 fpm descent rate and 174 knots ground speed. (Tab JJ-9) The last EGPWS data for the
MA prior to impact is at 1918:18L and shows the MA was in a 55 degree left bank, 11,752 fpm
descent rate, and at 165 knots ground speed. (Tab JJ-9) The times on the EGPWS are running
clock time. To have accurate times, the radar track data, EGPWS data, and radio transmissions
were compared to correlate the times to a synchronized time. (Tab JJ-3)
U-28A, TIN 07-0736, 18 February 2012
10
Figure 1. Descent profile provided by Enhanced Ground Proximity Warning System, looking
west. (Tab J-89)
Qj
3500
3000
2500
-g 2000 ....
E 1500
<
1000
500
0
EGPWS Data
0
-2000
-4000
-6000
-8000 ~
-10000 -MSL Altitude
-12000 -vertical Velocity
-14000
Figure 2. Enhanced Ground Proximity Warning System Data showing Altitude and Decent Rate
in feet per minute. (Tab JJ-9)
e. Impact
The MA impacted the ground five miles southwest of Ambouli International Airport in an
uninhabited and remote location strewn with boulders up to a two to three of feet in diameter, at
North 11 o 31.61' East 043° 04.41 ',265ft MSL. (Tab N-13) After initial impact, most of the MA
cleared the ridgeline before breaking apart.
U-28A, TIN 07-0736, 18 February 2012
11
Figure 3. Aerial view of crash site from CH-53, looking west northwest.
f. Egress and Aircrew Flight Equipment
The U-28A is not equipped with ejection seats. All required life support and survival equipment
inspections were up to date. (Tab K-35) There was no attempt to use the equipment after the
mishap. Most of the life support equipment was found at the crash site to include weapons,
radios, and handheld Global Positioning System (GPS) devices. (GG-3 to -5)
g. Search and Rescue
Approximately two minutes after the mishap, at 1919L, the control tower made five attempts to
reach the MA over the radio with no success. (Tab N-7) A local national heard the crash and
called the local police to report it around 1930L. (Tab N-15) Approximately 40 local police
officers arrived on the scene and searched for survivors until U.S. military personnel arrived.
(Tab N-16 to -17)
Approximately 16 minutes following the mishap, at 1935L, the crew of Ratchet 30 queried the
control tower at Ambouli to find out if the MA had landed. (Tab N-8) The control tower began
another query over the radio for the MA with no success. (Tab N-8) The control tower was
notified by a host nation civilian that the MA crashed six miles southwest of the airfield. (Tab NIl)
There is a 12-minute discrepancy between the tower mishap log and the Command Post
(CP) log on when the notification came in about the MA. (Tab N-12 to -13) According to the CP
log, the tower notified the CP at 1958L that the MA was reported down six miles southwest of
the airfield. (Tab N-13) At 2009L, the Executive Camp Commander put the Fire Department
unit on standby and called for all medical personnel to report to the Expeditionary Medical
Facility. (Tab N-13, -16)
At 2011L, Hoss 61, two United States Air Force (USAF) F-15Es, were recalled to provide an
overhead presence at the incident. (Tab EE-12) Hoss 61 arrived overhead at 2019L and
descended to get a better look. At 203 7L, Hoss 61 saw personnel moving around the site and
U-28A, TIN 07-0736, 18 February 2012
12
reported seeing personnel to Ratchet 30. (Tab EE-12) At 2041L, Eagle 80, a USAF MQ-1,
arrived overhead and reported seeing 3 hot spots, wreckage, 8 people, and two vehicles,
including one with a light bar on top. (Tab EE-10) Ross 61 returned to base by 2057L while
Eagle 80 remained overhead. (Tab EE-10, -12)
Naval Criminal Investigative Service (NCIS) agents were the first U.S. military personnel on the
ground at the scene and arrived at approximately 21 OOL with assistance from a local who knew
the area. (Tab N-16) The crash site was located a few miles off a road and was difficult to reach.
The NCIS agents determined that there were no survivors. (Tab N-16) At 2134L a Marine CH-
53 helicopter arrived with an Army Quick Reaction Force and USAF Pararescue Jumpers (PJs).
The lead PJ took over as the incident commander. (Tab N-16) At 2149L, the CP received the
call that all four souls on board were killed in action. (Tab N-13)
h. Recovery of Remains
The deceased personnel (MP, MCP, MOP1, and MOP2) were recovered from the mishap site by
the Pis and brought back to Camp Lemonnier. (Tab V-9.7) The remains were met at the gate by
the 34th Expeditionary Special Operations Squadron (ESOS) Commander where American flags
were draped over the remains before entering the camp and taken to the medical facility. (Tab V-
9.7) The next day, a memorial was held at Camp Lemonnier for the MC. The remains were
loaded onto a transport aircraft for the trip to Dover AFB, DE. (Tab V-9.7)
5. MAINTENANCE
a. Forms Documentation
(1) Discrepancy Records
Aircraft maintenance and inspections on the Pilatus U-28A/PC-12 aircraft are documented on
Form 8-40001-1 Discrepancy Records. (Tab D-7 to -9) History of these maintenance and
inspection actions is input and maintained in an electronic maintenance documentation system
called M3. (Tab D-4 7 to -67) In addition to documenting routine and scheduled maintenance
actions, these tools allow aircrews to report aircraft discrepancies and enable maintenance
personnel to document the actions taken to resolve the reported issues. Documentation includes
work instructions, planned action, corrective action taken, the maintenance personnel who
corrected and inspected the maintenance action (if required), and the date the problem was
corrected. Additionally, the discrepancy records and M3 provide maintenance personnel the
information necessary to research past aircraft problems to more effectively troubleshoot and
solve new maintenance discrepancies. (Tab D-7 to -9, -47 to -67)
Active discrepancy records are those that have not been corrected by maintenance personnel.
These discrepancies are evaluated to determine whether they affect the aircraft's airworthiness.
Airworthiness is a term used to describe whether an aircraft has been certified as suitable for safe
flight. Airworthiness is maintained by performing required maintenance actions by licensed
maintenance personnel. If maintenance personnel determine discrepancies do not affect
airworthiness, the aircraft can be flown without corrective action. There were three active
U-28A, TIN 07-0736, 18 February 2012
13
discrepancy records at the time of the mishap flight, none of which affected airworthiness. (Tab
D-7 to -9)
I Record#
I B54558
I B42617
I B82130
I Discrepancy I Action Taken
I A ux comm disconnected rl: -M-::i:-ss--=i-o_n_e-'-q-u-:-pi m_e_n_t_, --=-do_e_s_n_o_t_a--=f=-=fe--c'--t.:..:.a;;_i..r w--.o _rt_;_h_i_n'--es'--_s'--_; ;._:____
I Line ready unitsremov(!d .I Doesn't~ffe~tail'\Vorthine~~; V(!~if1~4_w.eigl1:~~~1~1.1~~-.
I
Monitor soft keys not I Bad USB cable; part on order; mission equipment, '
working does not affect airworthiness . .. ... ... .... .. ... ... . .. .. . .... ... . . . . .. ..
Table 1. Open Discrepancy Records.
Airworthiness Directives (ADs) are legally enforceable rules issued by the Federal Aviation
Administration (FAA) in accordance with the Code of Federal Regulations, Title 14, Part 39, to
correct an unsafe condition in an aircraft, aircraft engine, propeller, or appliance. There were
seven ADs issued by the FAA for the MA since acceptance of the MA by the Air Force on
7 May 2007. (Tab II-7) Maintenance personnel complied with all seven ADs. They documented
their actions on a discrepancy record and in M3. (Tab U-5 to -11)
A review of maintenance documentation was completed to determine whether historical records
revealed any recurring maintenance problems on the MA. Discrepancy records and M3
documentation from 1 January 2011 to 18 February 2012 revealed no such recurring issues (Tab
II-7).
(2) Aircraft Flight Hours/Engine Hours
Aircraft flight hours are tracked and documented to ensure that scheduled inspections are
accomplished on time and to help determine overall wear and tear on the aircraft and its
components. Prior to the MS, the MA had accumulated 8,981.8 total flight hours. Engine hours
are tracked to monitor the total life of an engine, the total hours since last overhaul, the date of
last install, and the hours since installation. Prior to the MS, the mishap engine, PT6A-67B,
serial number PCE-PR0357, had accumulated 5,490.6 total engine hours. 2,023.4 hours had
accumulated since the last overhaul on 2 June 2010. Overhauls are required every 3,500 hours
on PT6A-67B engines. The mishap engine was installed on the MA on 9 August 2011. The
mishap engine had accumulated 205.9 hours since installation. (Tab D-3)
b. Inspections
(1) Preflight/Postflight
Maintenance personnel complete an inspection prior to and after each flight, which are referred
to as preflight and postflight inspections respectively. The purpose of these inspections is to
visually inspect and operationally check various areas and systems of the aircraft in preparation
for a flying period. The U-28A/PC-12 Pilot's Operating Handbook, Section 4, directs these
inspections, which are documented on a daily flight log. (Tab BB-7 to -14) The daily flight log
also includes other pertinent flight data: airframe and engine data, servicing log, flare status, time
U-28A, TIN 07-0736, 18 February 2012
14
before next inspection, maintenance release and flight times. Documentation was completed as
required for the preflight inspection, servicing, and maintenance release of the MA on the daily
flight log, dated 18 February 2012. (Tab D-5)
(2) Progressive Inspection Program
The progressive inspection program is designed for high utilization aircraft. For every aircraft
maintained under this program, a complete inspection cycle consists of six mini or minor
inspections and six phase inspections at alternating intervals every 100 hours. This must be
complied with while not exceeding 1200 hours time in service or 12 months, whichever comes
first. The mini inspection consists of a visual inspection of the wing, tail, fuselage, landing gear,
fluid levels, cabin, cockpit, propeller, engine oil filter, and fuel filter. The phase 1 through 6
inspections include all 1 00-hour and annual tasks as well as time limited and overhaul tasks that
fall within 12 calendar months. Once the 1200-hour cycle and all inspections in the program are
completed, the cycle starts over. (Tab U-15)
1 00-hour phase inspections may be completed and signed off between 10 hours prior to or after
the due time without altering the due time of the next 1 00-hour inspection. (Tab U -15) A 400-
hour Progressive Phase 2 inspection was conducted on the MA on 15 February 2012 (Tab D-66),
2.7 hours prior to the accumulated 100 hours (Tab U-3). The maintenance conducted in
conjunction with the Phase 2 inspection is contained in the discrepancy records listed in M3.
(Tab D-63 item 3 to D-67 item 2)
The MA flew five sorties totaling 26.6 hours between the 400-hour inspection and the MS. (Tab
D-43, -44, -46) A documentation error was noted in the daily flight logs for those five sorties.
Although the 400-hour inspection was complied with as previously mentioned, the 400-hour
Phase 2 inspection was still listed as the next inspection due. (Tab D-43, -44, -46) This minor
discrepancy had no bearing on the mishap.
c. Maintenance Procedures
Prior to launching an aircraft, many maintenance actions and procedures must be completed and
documented to include servicing, preflight, maintenance release, and time before next scheduled
inspection. Documentation of these actions is required on a daily flight log. The most common
servicing operations include fuel, engine oil, and tire pressure. Preflight inspections are
completed and documented prior to each sortie. Once the servicing log and preflight inspection
is complied with, a review of discrepancy records and M3 is conducted to ensure there is no
maintenance action ongoing that would affect airworthiness of the aircraft. Once complete, a
FAA certified Airframe and Powerplant (A&P) mechanic signs the maintenance release section.
(Tab D-5)
At the end of the day's flying period, additional actions are required. A postflight inspection is
completed to verify the continued airworthiness of the aircraft. The day's sorties are tallied to
keep track of aircraft and engine operating time. This is recorded in M3 to ensure time tracked
components are changed per the items' life expectancy, while also ensuring scheduled
U-28A, TIN 07-0736, 18 February 2012
15
inspections are completed when required. The type of the next upcoming inspection and hours
until due are included on the daily flight log. (Tab D-15 to -46)
d. Maintenance Personnel and Supervision
The Sierra Nevada Corporation (SNC) is a contractor logistics support organization that provides
maintenance for the U-28A/PC-12 at Hurlburt Field, FL and any forward deployed locations.
SNC employs FAA certified A&P mechanics, FAA certified Inspection Authorized (IA)
mechanics and avionics specialists to maintain the U-28A/PC-12. The SNC A&P mechanics
complete a theoretical and practical familiarization program on servicing and maintenance within
the context of the Pilatus PC-12 maintenance manual on airframe, powerplant, controls and
associated systems, including engine ground runs and taxi operations. Avionics mechanics
complete a theoretical and practical familiarization program on servicing and maintenance within
the context of the Pi latus PC-12 maintenance manual on electrical systems, airframe, power plant
controls, reduced vertical separation minimum requirements, along with all avionics systems,
including engine ground runs and taxi operations. (Tab II-7)
SNC maintains a training record for each SNC maintenance member that includes, if applicable:
job description, A&P certification, Inspection Authorization, certificates of training,
familiarization training documentation, prior aircraft training, on-the-job training and Air Force
deployment-related computer based training. Maintenance training records were reviewed for
the SNC personnel deployed to Djibouti with the U-28A aircraft. The training records for
personnel who worked on the MA met or exceeded FAA requirements. (Tab II-7)
e. Fuel and Oil Inspection Analyses
(1) Fuel
SGS Oil, Gas and Chemical Services of Djibouti conducted analysis of the JP-5 fuel used in the
MA to ensure it was not a factor in the mishap. Analysis included tests for appearance, density,
flashpoint, particle matter, and filtration time. Results cited in the completed certificate of
analysis were unremarkable. (Tab D-71)
(2) Oil
An engine oil-servicing cart, serial number 7944101201, was used on 15 February 2012 to
service the MA. A review conducted on the cart's serviceable equipment tag showed
documentation of the required monthly inspection on 2 February 2012 and six-month filter
replacement on 18 December 2011. (Tab D-73) Aviation Laboratories analyzed an oil sample
collected from the servicing cart to ensure it was not a factor in the mishap. Results cited in the
completed analysis were unremarkable. (Tab D-75)
Given the extensive physical damage to the engine from the mishap, normal collection of the oil
sample was not possible. However, an oil sample was collected post mishap from the remains of
the mishap engine's oil cooler and forwarded to Aviation Laboratories for analysis. The sample
consisted of debris sent in a jar that included a major amount of dirt and grit. Metal that was
U-28A, TIN 07-0736, 18 February 2012
16
found in the debris consisted of 1 piece of stainless steel, 100 fine wear pieces of carbon steel,
and 60 fine wear pieces of alloy steel. The two most recent analysis reports for the mishap
engine oil cooler prepared prior to the MS stated that the samples appeared normal. (Tab D-77)
(3) Unscheduled Maintenance
As mentioned above in paragraph 5.b.2., the last scheduled inspection was completed on
15 February 2012. Between the 400-hour Progressive Phase 2 inspection and the MS, aircrew
reported three discrepancies, resulting in unscheduled maintenance. Each discrepancy was
reported on a discrepancy record and documented in M3. (Tab D-67) SNC personnel conducted
maintenance on each system and cleared all three discrepancies after operation checks were
normal. Each unscheduled maintenance action involved mission equipment that would not
impact airworthiness.
6. AIRFRAME SYSTEMS
a. Structures and Systems
The condition of the MA rendered many components destroyed beyond recognition and/or
damaged to a state that would not allow for analysis or evaluation. The only sections of the
aircraft that were mostly intact were the right wing and tail (vertical and horizontal stabilizer).
This type of aircraft is not equipped with a cockpit voice recorder or a flight data recorder.
However, several structures and systems were recovered in a condition that could be evaluated
and considered potentially relevant to the mishap investigation. None of the parts recovered
indicated a problem with the MA prior to the impact.
(1) Mishap Engine
a. Powerplant
Pratt & Whitney Investigation Facilities in Bridgeport, WV evaluated the recovered mishap
engine. The evaluation concluded that damage to the lower gas generator case suggested that the
engine and aircraft were upright when they impacted the ground. Further investigation revealed
that the 1st stage compressor blades were bent opposite the direction of rotation, which indicated
that the blades were rotating upon impact. Rubbing between several components and the sheared
turbine shaft was linked to impact loads and internal/external housing deformation. The Pratt &
Whitney investigation concluded that: "The engine displayed contact signatures to its internal
components characteristic of an engine producing power at the time of impact. The engine did
not display any evidence of any pre-impact distress or anomalies that would have prevented
normal engine operation prior to impact." (Tab J-39)
b. Propeller
Some propeller components from the mishap engine were able to be recovered and sent to
Hartzell Propeller Inc. in Piqua, OH for evaluation. Due to damage to the parts, and some parts
never being recovered, a significant assessment of the propeller was not possible. Nevertheless,
an impact mark between the piston and cylinder was noted. This mark could indicate a blade
U-28A, TIN 07-0736, 18 February 2012
17
angle lower than the flight idle position; however, the evaluation notes that impact often drives
the pitch change mechanism toward a lower blade angle. Several reasons were given for why it
is unlikely that this mark reflects a pre-impact blade angle. (Tab J-72) The Hartzell Propeller
investigation concluded that: "An evaluation of power output could not be determined. Damage
was indicative of frontal impact at high speed. There were no discrepancies noted that would
preclude normal operation. All damage was consistent with impact damage." (Tab J-72)
(2) Enhanced Ground Proximity Warning System
The EGPWS was recovered and forwarded to Honeywell in Redmond, W A for analysis. The
report noted that the most up-to-date version of the terrain database was not in use. Honeywell
confirmed that the outdated database did not affect EGPWS operation due to airport/terrain
information near Djibouti remaining unchanged between the version in use and the most updated
version. (Tab J-87) The EGPWS unit was heavily damaged, but the flash chip on the circuit
board that contains flight history non-volatile memory was not damaged. Honeywell was able to
make a full download of the flight history by removing the chip from the board and installing it
in a chip reader. All indications suggest the EGPWS was fully functional at the time of the
mishap. (Tab J-88) The data from the flash chip was processed and used by investigators to
recreate the last 27 seconds of the MA's flight track. (Tab JJ-3 to -8)
(3) Attitude Indicator
One of the MA's standby attitude indicators was recovered and forwarded to L3
Communications Avionics Systems in Grand Rapids, MI for evaluation. Based on external
evaluation of the component it was determined that during the mishap, both the mechanical and
electrical components of the attitude indicator were damaged extensively. L3 noted the gimbal
alignment and damage to the rotor suggested that the aircraft may have been in a steep dive of up
to 70 degrees nose down. L3 evaluation concluded that "the unit showed no evidence of
abnormal operation prior to the mishap." (Tab HH-3) The 70 degrees nose down is inconsistent
with the flight data recovered from the EGPWS and may reflect a position after initial impact.
(Tab JJ-9)
( 4) Flight Control Trim Tabs
The horizontal stabilizer trim, aileron trim, and rudder trim actuators were removed from the
wreckage and forwarded to Pilatus for evaluation. The purpose of the evaluation was to
determine the position of each flight control trim at the time of the mishap.
a. Horizontal stabilizer trim
The horizontal stabilizer trim actuator was still intact and connected to the horizontal stabilizer
post mishap. The actuator was removed from its mount position within the vertical stabilizer.
Horizontal stabilizer trim position was determined by measuring the extension rod of the
actuator. The measurement was consistent with a trim setting of nearly neutral. (Tab HH-21)
The Pilatus report states that the post-mishap position of the trim actuator would be identical to
the pre-mishap position assuming that there was no internal damage to the actuator. The forward
portion of the horizontal stabilizer was severely impacted and damaged during the mishap. The
U-28A, TIN 07-0736, 18 February 2012
18
trim actuator, which mounts to the forward portion of the stabilizer, also showed evidence of
impact at the lower mount, which was cracked and bent roughly 30 degrees from normal. (Tab
HH-25 to -26) Due to the damage, internal evaluation of the actuator was conducted by the Air
Force Research Laboratory at Wright-Patterson AFB, OH. A thorough examination showed no
damage to the internal components of the actuator that would suggest the post-mishap position
was different from the pre-mishap position. (Tab HH-37 to -38)
b. Aileron trim
The aileron trim actuator is attached only to the left wing aileron trim tab. Even though the left
wing and actuator were severely damaged during the mishap, it was still possible to determine
the aileron trim position by measuring the extension rod of the actuator, which was still intact.
(Tab HH-16) The measurement was consistent with a slight left aileron trim, which is within
normal takeoff range, which is appropriate for this phase of flight. (Tab HH -17)
c. Rudder trim
The rudder trim actuator was still intact and undamaged post mishap. The actuator was removed
from its normal mount position inside the vertical stabilizer. The rudder trim position was
determined by measuring the extension rod of the actuator. The measurement was consistent
with full left rudder trim. (Tab HH -18) When the yaw damper is engaged and active, the auto
trim function is also active. The yaw damper provides turn coordination for the aircraft's yaw
axis through an auto trim function that automatically operates the aircraft's rudder trim system.
(Tab U -17 to -18) It is normal practice to engage the yaw damper shortly after takeoff and only
disengage it prior to landing. The yaw damper is required to be in the off position prior to
takeoff and landing. (Tab BB-15) Otherwise, it is normal to have the yaw damper engaged
during flight to auto trim the rudder trim system. Full left rudder trim position is possible when
the yaw damper is commanding the trim position in a left hand turn, as was the case during the
last 13 seconds of the MS, which is consistent with the yaw damper being engaged and active.
(Tab JJ-7)
(5) Flaps
The flaps were evaluated to determine the position at the time of the mishap. Each wing has two
jackscrew type flap actuators. Three of the four actuators were recovered from the wreckage and
evaluated by Pilatus to determine flap positioning. The fourth actuator could not be located.
Each of the three flap actuator jackscrews were sheared off during the mishap. However, Pilatus
was able to conclude that each actuator was at the "in" position, which correlates to flaps up.
(Tab HH-13 to -14) The flaps should have been in the up position due to the airspeed prior to the
mishap. The airspeed limitation for flap operation to 15 degrees is 163 KIAS and greater than 15
degrees is 130 KIAS. (Tab BB-6) The lowest airspeed recorded during the mishap sequence is
165 knots ground speed, one second prior to impact. (Tab JJ-9)
(6) Airspeed Indicator
The face of the MA's airspeed indicator was recovered and forwarded to the National
Transportation Safety Board (NTSB) in Washington, DC for evaluation. There was a clear
U-28A, TIN 07-0736, 18 February 2012
19
indicator mark identified at the 350-knot position. The NTSB determined that the mark
identified was made by the max allowable indicator needle, not the airspeed needle. There were
no other marks found on the face consistent with indicator needle marks; therefore, the airspeed
needle position at the time of the mishap could not be determined. (Tab HH-27 to -31)
(7) Emergency Locator Transmitter
The Emergency Locator Transmitter (ELT) was recovered and forwarded to ACR Electronics for
evaluation to determine if the beacon activated post mishap. The on/off switch was damaged and
not functional. The battery assembly and EL T encasement was tom open, but the battery was
still in place. Nevertheless, battery usage data could not be retrieved. During the EL T
investigation, a test connector was installed and the component was activated manually, but "no
signals on any frequency were emitted from the ELT." (Tab HH-24)
(8) Other Evaluated Components
There were several other components examined in an attempt to capture all possible mishap data.
Both LCR-100s from the Altitude Heading Reference System (Tab HH-12), both of the Air Data
Modules (Tab HH-9), the stick pusher computer (Tab HH-12), and the Air Data Computer (Tab
HH -13) were all evaluated to determine whether any significant information could be retrieved.
No relevant information could be recovered from any of the components.
7. WEATHER
a. Forecast Weather
At brief time, weather for takeoff was forecast to have a scattered layer of clouds at 4000 ft AGL
with the winds from the east, 080 degrees at 12 knots gusting to 18 knots and unlimited
visibility. (Tab F-7) The forecast weather at the time of landing was clear skies with winds from
the Southeast, 120 degrees at 6 knots and unlimited visibility. (Tab F-7) There were no
forecasted thunderstorms for the area and route of flight. Sunset was at 1815 local time and
moonrise was at 0414 local time on 19 February 2012 with a moon illumination of 9%. (Tab F -7)
End of Evening Nautical Twilight was 1901L, the time when the sun's light is below the horizon.
(Tab F-7) At the time ofthe incident, the moon was not up and the sun was down. (Tab F-7)
b. Observed Weather
At the time of the mishap, Camp Lemonnier was reporting skies clear with winds from the east,
110 degrees at 6 knots and unlimited visibility. (Tab F-3) Weather given to the MC by Djibouti
approach control when the MA entered Djiboutian airspace was: winds from the east at 120
degrees and 9 knots, visibility 15 kilometers (over 9 miles), few clouds at 600 meters (about
2000 ft), temperature 27 degrees Celsius (80 degrees Fahrenheit), and the altimeter setting of
1012 millibars (29.88 inches of mercury), which is barometric pressure adjusted to sea level.
(Tab N-3) Post-mishap weather, recorded at 1955L was a few clouds at 2000 feet AGL, winds
from the east, 110 degrees at 5 knots and unlimited visibility. (Tab F-3) Weather was not a
factor in the mishap.
U-28A, TIN 07-0736, 18 February 2012
20
c. Space Environment
Not applicable.
d. Operations
Based on the forecast, the weather was within limits for the mission. Operations were conducted
in accordance with applicable directives.
8. CREW QUALIFICATIONS
a. Mishap Pilot
The MP was a current and qualified Evaluator Pilot with 2316.8 total flight hours including
2213.1 hours in the PC-12/U-28A, 1403.3 hours of combat, 903.2 hours with NVGs, 547 total
sorties, and 273 combat sorties. (Tab G-7 to -19, -73) The MP arrived at Camp Lemonnier,
Djibouti on 16 January 2012 and was on his ninth combat deployment. (Tab DD-3) The MP was
on the 20th combat sortie for his current deployment. (Tab G-17 to -19)
The MP had been previously deployed to Djibouti from September to October 2010. (Tab DD-3)
The MP was last deployed from 11 June 2011 to 3 September 2011 and returned to Hurlburt
Field for four months prior to this deployment. (Tab DD-3) During this time, the MP upgraded
to Evaluator Pilot. (Tab T-8)
The MP was an Advanced Instrument School (AIS) graduate and was considered to be a
conservative pilot. (Tab V-6.4, -6.25 to -6.26) The MP was known to be a pilot that flew both
looking outside the cockpit for visual reference and inside the cockpit backing up with
instruments, and would always have backup instrument approaches loaded even in visual flight
rules (VFR) conditions. (Tab V-2.7, -2.8, V-6.4) According to other members of the squadron,
the MP was a good instructor that tried to impart knowledge on the crew force. (V-6.4, -6.25 to-
6.26)
At the time of the mishap, the MP's recent flight time was as follows (Tab G-9):
Hours Sorties
30 D~y_s 94.8 19
60 Days 110.5 24
90 Days 132.4 32
Table 2. Mishap Pilot's 30/60/90 Day Flying Report.
b. Mishap Copilot
The MCP was a current and qualified Mission Pilot with 1245.9 total flight hours including
1245.1 hours in the PC-12/U-28A, 817.4 hours of combat, 439.7 hours with NVGs, 270 total
U-28A, TIN 07-0736, 18 February 2012
21
sorties, and 151 combat sorties. (Tab G-25 to -27, -83) The MP arrived at Camp Lemonnier,
Djibouti on 16 February 2012 and was on his fomih combat deployment. (Tab DD-4) The MCP
was on his first sortie for the current deployment (Tab G-35). The MCP had been previously
deployed to Djibouti from 13 May to 19 July 2011 and returned to Hurlburt Field for six months
prior to this deployment. (Tab DD-4)
The MCP was known to be a very detail oriented pilot that would use a crew mentality on every
flight. (Tab R-4 to -5) The MCP was a highly regarded officer and a real stand up individual.
(Tab R-88) The MCP was known to be very engaged in the flight, even when not at the controls.
(Tab R-4 to -5)
At the time of the mishap, the MCP's recent flight time was as follows (Tab G-27):
Hours Sorties
30 Days 10.8 3
60 Days 20.9 6
90 Days 56.6 17
Table 3. Mishap Copilot's 30/60/90 Day Flying Report.
c. Mishap Operator 1
The MOPl was a current and qualified Combat Systems Officer with 554.8 total flight hours all
in the PC-12/U-28A, 430 hours of combat, 114 total sorties, and 79 combat sorties. (Tab G-39 to
-41, -91) The MOP1 arrived at Camp Lemonnier, Djibouti on 16 February 2012 and was on his
third combat deployment. (Tab DD-4) The MOP1 was on his first combat smtie for the current
deployment. (Tab G-51) The MOPl had been previously deployed to Djibouti from 29 October
to 18 December 2011 and returned to Hurlburt Field for two months prior to this deployment.
(Tab DD-4)
The MOPl was a very highly regarded officer in the squadron. (Tab R-88)
At the time ofthe mishap, the MOP1 's recent flight time was as follows (Tab G-41):
Hours Sorties
30 Days 11.1 3
60 Days 16.3 5
90 Days 121.9 24
Table 4. Mishap Operator 1 's 30/60/90 Day Flying Report.
d. Mishap Operator 2
The MOP2 was a current and qualified Tactical Systems Operator with 924.1 total flight hours,
153.7 hours in the PC-12/U-28A, 845.6 hours of combat, 226 total sorties, and 205 combat
sotiies. (Tab G-56 to -59, -97) The MOP2 arrived at Camp Lemonnier, Djibouti on 20 January
U-28A, TIN 07-0736, 18 February 2012
22
2012 and was on his third combat deployment. (Tab DD-5) The MOP2 was on his 16th combat
sortie for the current deployment. (Tab G-71 to -72)
This was the MOP2's first deployment to Djibouti and was last deployed from 24 June 2011 to
15 September 2011. (Tab DD-5) He returned to Hurlburt Field for four months prior to this
deployment.
The MOP2 was a detail oriented person that was always seen studying the job at hand and
gathering as much knowledge as possible on the mission tasks. (Tab R-1 06)
At the time of the mishap, the MOP2's recent flight time was as follows (Tab G-57):
Hours Sorties
30 Days 74.5 15
60 Days 74.5 15
90 Days 77.9 16
Table 5. Mishap Operator 2's 30/60/90 Day Flying Report.
9. MEDICAL
a. Qualifications
The MP was medically qualified to perform flying duties at the time of the incident. His most
recent Preventative Health Assessment (PHA) was performed on 21 December 2011, and he was
issued a Medical Recommendation for Flying or Special Operational Duty (Air Force Form
1 042) indicating that he was cleared for duty following his periodic medical examination. It was
noted that the MP required vision correction devices such as glasses or contacts while
performing flight duties. (Tab DD-1 0) MP was enrolled in the Aircrew Soft Contact Lens
Program and was current in this program with his most recent optometry appointment occurring
on 15 April 2011. A review of Aeromedical Information Management Waiver Tracking System
(AIMWTS) indicated that the MP never required a medical waiver. (Tab X-3)
The MCP was medically qualified to perform flying duties at the time of the incident. His most
recent PHA was performed on 20 January 2012, and he was issued a Form 1042 indicating that
he was cleared for duty following his periodic medical examination. (Tab DD-9) A review of
AIMWTS indicated that the MCP had a valid medical waiver to allow him to fly. The waiver
was granted by AFSOC and was valid until 31 January 2013. (Tab X-3)
The MOPl was medically qualified to perform flying duties at the time of the incident. His most
recent PHA was performed on 3 February 2012, and he was issued a Form 1042 indicating that
he was cleared for duty following his periodic medical examination. (Tab DD-7) A review of
AIMWTS indicated that the MOPl never required a medical waiver. (Tab X-3)
The MOP2 was medically qualified to perform flying duties at the time of the incident. His most
recent PHA was performed on 26 May 2011, and he was issued a Form 1042 indicating that he
U-28A, TIN 07-0736, 18 February 2012
23
was cleared for duty following his periodic medical examination. (Tab DD-8) A review of
AIMWTS indicated that the MOP2 never required a medical waiver. (Tab X-3)
b. Health
The outpatient medical and dental records as well as the military electronic medical record for
each member of the MC were reviewed. No significant health issues were identified for any
member of the MC. (Tab X-3)
c. Pathology
The remains of the MC were transported to Dover Port Mortuary at Dover AFB, DE. Autopsies
were performed and the cause of death was determined to be multiple injuries for each of the
MC. Toxicology tests were performed on each of the MC with no evidence of unapproved
medication use. There was no evidence of alcohol or any illegal substance playing a role in the
accident. The MP was noted to have a carboxyhemoglobin level of 8%. Levels below 10% are
considered normal in a post-mortem sample. (Chaturvedi, Arvind K., "Aviation Combustion
Toxicology: An Overview," Journal of Analytical Toxicology, Vol. 34, 2010)
d. Lifestyle
No lifestyle factors were found to be relevant to the mishap.
e. Crew Rest and Crew Duty Time
API 11-202, Volume 3, indicates that the crew rest period is normally at least a 12-hour non-duty
period before the aircrew enters the flight duty period. The purpose of crew rest is to ensure the
aircrew member is adequately rested before performing flight or flight related duties. Crew rest
is free time, and includes time for meals, transportation and rest. Aircrew members require at
least 1 0 continuous hours of restful activities (including an opportunity for at least 8 hours of
uninterrupted sleep) during the 12 hours immediately prior to the flight duty period.
The MC was afforded adequate crew rest in the time leading up to the accident. However, on the
day prior to the incident, there was an exercise scenario at the deployed location.
Announcements regarding this exercise were broadcast to the base utilizing a loudspeaker
system. One of the speakers for the system was located near the sleeping quarters of the aircrew.
(Tab V-4.18) A lost sleep list was initiated by the MP to document any crew members in the
squadron that had their sleep interrupted by the exercise announcements. (Tab V -4.23) Only one
member of the MC, the MOP1, was included on the lost sleep list (Tab K-23), although his
roommate reported that he appeared to have slept well (Tab EE-3). Even though the MP did not
put his name on the list, he mentioned that the exercise announcements did affect his sleep. (Tab
V -4.23) The ORM worksheet, a risk management tool that was filled out by the MC prior to the
flight, showed that the MC determined that the risk stemming from preflight fatigue was low.
(Tab K-11)
U-28A, TIN 07-0736, 18 February 2012
24
The deployed unit utilized a block schedule system to minimize the effects of changing duty
times on the Airmen's circadian rhythm. Aircrew were placed into a certain block of time for
scheduling purposes and they stayed in this block allowing the aircrew to maintain a regular
schedule. The MP had recently been given additional duties as a mission commander. Along
with this came a shift to a later block. (Tab R-24) This allowed the MP to attend meetings that
came along with his additional duties. The MP was left off of the flying schedule for two days
prior to the mishap to allow him time to adjust to the new block time. (Tab G-18)
10. OPERATIONS AND SUPERVISION
a. Operations
At the time of the mishap, the 34 ESOS was running operations 24 hours a day, seven days a
week. The operations tempo was robust with 16 sorties spread out over every 24 hour period.
The sorties were divided up through block scheduling so that the crews' circadian rhythm would
not be affected. The leadership tried to keep crews in the same blocks and if crews had to
change blocks, they would get two days off in between to adjust the circadian rhythm. (Tab V-
9.3) The crewmembers continuously rotate through the deployed location as the squadron has
been continuously deployed there. The MP deployed to Djibouti on 16 January 2012 and was on
his third Djibouti deployment with 2,316 total hours of flight time. (Tabs DD-3, G-8) The MCP
deployed to Djibouti on 14 February 2012 and was on a third deployment to Djibouti with 1,245
total hours of flight time. (Tabs DD-4, G-25) The MOP1 deployed to Djibouti on 14 February
2012 and was on his third deployment to Djibouti with 554 total hours of flight time. (Tabs DD-
4, G-39) The MOP2 deployed to Djibouti on 20 January 2012 for his first deployment to
Djibouti with 924 total hours of flight time. (Tabs DD-5, G-56) The MS was the first sortie on
this deployment for the MCP and the MOP1 and thus the MC had not flown together on this
deployment before the MS. (Tab G-27, -41)
There is no evidence to suggest that squadron operations tempo was a factor.
The mission was properly authorized and approved by the 34 ESOS Commander. (Tab K-5) A
records review showed that all MC were current and qualified to participate in the scheduled
sortie. (Tab G-3 to -71) The flight planning was done by the duty desk prior to the MS to
include flight plan, weather, NOTAM, and weight and balance. (Tabs V-9.5, K-3 to -16) The
weight and balance incorrectly showed the life raft placement in the rear of the aircraft and was
corrected post incident at the request of the 34 ESOS Commander. (Tabs K-7, V-9.5) The ORM
worksheet, which was filled out by the MC, made no mention of the low illumination that was
planned for the night of the incident nor, as required by AFI 11-2U28, Volume 3, paragraph
6.18.1, which requires an extra level of ORM when moon illumination is less than 10%. (Tab K-
11 to -12, BB-3 to -4) The forecasted moon illumination for the night of the mishap was 9%,
which should have required an extra level of ORM, but was not accounted for on the ORM
worksheet. (Tab F -7) The MC briefed on their own, so it is unknown if the crew brief included a
discussion about the low moon illumination and the visual illusions that can accompany it. (Tab
EE-6)
U-28A, TIN 07-0736, 18 February 2012
25
There is no evidence to suggest deployed procedures, planning, preparation and briefing were a
factor.
b. Supervision
The leadership of the 34 ESOS provided adequate supervision. The leadership identified fatigue
as a potential issue due to the 24/7 operations tempo of the deployed unit and implemented
measures such as block scheduling and down days if the aircrew's schedule needed to shift. (Tab
V-9.4) The leadership also implemented a policy in which on the first sortie of the deployment,
the new pilot will observe the take-off and landing and not perform them. (Tab V-9.3) The MC
was a mixed crew from different squadrons. The MP was a member of the 319 SOS, the MC
and MOP1 were members of the 34 SOS, and the MOP2 was a member of the 25 IS. All MC
were well trained for the mission and the deployment. (Tab K-5)
There is no evidence to suggest that deployed supervision was a factor.
11. HUMAN FACTORS ANALYSIS
a. Overview
The DoD Human Factors Analysis and Classification System (HF ACS) is a system that allows
for categorization of human factors when it comes to investigating mishaps. (API 91-204, Safety
Investigations and Reports, 24 September 2008, Attachment 5) Human factors are not just about
the humans. They are about how features of people's tools, tasks and working environment
systematically influence human performance. The HF ACS model is designed to present a
systematic, multidimensional approach to error analysis. The HF ACS system describes four
main levels of human factors that may have contributed to the mishap. These four levels are
Acts, Preconditions, Supervision and Organizational Influence and are described in more detail
below:
Acts are those factors that are most closely tied to the mishap, and can be described as
active failures or actions committed by the operator that result in human error or an
unsafe situation. Acts may be either errors or violations. Errors are factors in mishaps
when mental or physical activities of the operator fail to achieve their intended outcome
as the result of skill-based, perceptual, or judgment and decision making errors leading to
an unsafe situation. Errors are unintended. Violations are factors in a mishap when the
actions of the operator represent willful disregard for rules and instructions and lead to an
unsafe situation. Violations are deliberate.
Preconditions are factors in a mishap if active and/or latent preconditions such as
conditions of the operators, environment or personal factors affect practices, conditions
or actions of individuals and result in human error or an unsafe situation.
Supervision is a factor if the methods, decisions or policies of the supervisory chain of
command directly affect practices, conditions, or actions of individuals and result in
human error or an unsafe situation.
U-28A, TIN 07-0736, 18 February 2012
26
Organizational influences are factors in a mishap if the communications, actions,
omissions or policies of upper-level management directly or indirectly affect supervisory
practices, conditions or actions of the operator(s) and result in system failure, human
error or an unsafe situation.
Multiple interviews were conducted and volumes of documents were reviewed to support human
factors analysis. The unavailability of eyewitness accounts and cockpit voice recordings were
significant limiting factors. However, based on the evidence recovered from the mishap, the
board considered the following human factors and found them to be relevant:
b. PC508 Spatial Disorientation (Type 1) Unrecognized
Spatial Disorientation is a failure to correctly sense a position, motion or attitude of the
aircraft or of oneself within the fixed coordinate system provided by the surface of the
earth and the gravitational vertical. Spatial Disorientation (Type 1) Unrecognized is a
factor when a person's cognitive awareness of one or more of the following varies from
reality: attitude; position; velocity; direction of movement or acceleration. Proper control
inputs are not made because the need is unknown. (AFI 91-204)
There is no evidence that there was a mechanical failure with the MA. There is no
evidence for a sudden medical incapacitation prior to impact with any of the MC. The
flight profile flown by the MC is consistent with spatial disorientation. There is no
indication that the MC applied any flight control inputs showing that they were aware of
the correct position of the MA, which is indicative of unrecognized spatial disorientation.
(Tab JJ-9) Unrecognized Spatial Disorientation would explain the failure of the MC to
take corrective action in response to the position of the MA.
c. PC503 Illusion - Visual
Illusion - Visual is a factor when visual stimuli result in an erroneous perception of
orientation, motion or acceleration, leading to degraded performance. (AFI 91-204)
The MA was sent to the west of the airfield because of traffic in the pattern. (Tab N-7)
This area has minimal cultural lighting (Tab V -4.11 to -4.12) and a "black hole" was
described out to the west and south of the airfield. (Tab V -6.11, -6.19) At the time of the
mishap there was no lunar illumination. (Tab F-7) With the use of NVGs the field of
view is limited and depth perception is reduced. This reduction in visual clues could
have caused the MC to have a false perception of their altitude, attitude and descent rate.
This could have caused the MC to become spatially disoriented.
d. PC502 Illusion - Vestibular
Illusion - Vestibular is a factor when stimuli acting on the semicircular ducts or otolith
organs of the vestibular apparatus cause the individual to have an erroneous perception of
orientation, motion or acceleration leading to degraded performance. (AFI 91-204)
U-28A, TIN 07-0736, 18 February 2012
27
The G-excess illusion occurs when a pilot enters a greater than 1 G (1 times the force of
gravity) turn with the aircraft, looks back into the turn and experiences the sensation that
the aircraft is leveling out from the roll and having a pitch up attitude. Given this input
the pilot will often apply more bank and nose-down pitch in order to maintain the desired
bank angle and pitch. (Newman, David G, An overview of spatial disorientation as afactor in
aviation accidents and incidents, Flight Medicine Systems Pty Ltd, Dec 2007) The unintended
consequence is that the aircraft experiences significant overbank and descent. (Tab Z-5)
In a situation where the aircraft is already at a low altitude, this could cause a controlled
flight into terrain. The G-excess illusion causes pilots to increase bank angle and pitch
forward as they perceive the aircraft to be leveling out and pitching up, which matches
the mishap flight profile. (Tab JJ-9) This could have caused the MC to become spatially
disoriented.
e. AE205 Caution/Warning- Ignored
Caution/Warning - Ignored is a factor when a caution or warning is perceived and
understood by the individual but is ignored by the individual leading to an unsafe
situation. (AFI 91-204)
When replicating the flight parameters in the simulator, the MA could be controlled and
pulled out of the descent if the MC had applied the correct flight control inputs when
auditory alerts were given by the EGPWS. There is no evidence to indicate that the MC
applied any corrective inputs to the flight controls when the EGPWS issued the auditory
alerts of "Sink Rate" and "Pull Up." (Tab JJ-9) This factor was felt to contribute to the
mishap.
f. PC102 Channelized Attention
Channelized Attention is a factor when the individual is focusing all conscious attention
on a limited number of environmental cues to the exclusion of other of a subjectively
equal or higher or more immediate priority, leading to an unsafe situation. It is a tight
focus of attention that leads to the exclusion of comprehensive situational awareness.
(AFI 91-204)
When looking at the data retrieved from the EGPWS, the MC showed no signs of pulling
up in response to the "Sink Rate" and "Pull Up" auditory alerts. (Tab JJ-9) This could
happen if they were focusing all of their attention on some other factor and these alerts
were not consciously addressed. The evidence raises the possibility of this being
involved.
g. PC307 Fatigue -Physiological/Mental
Fatigue - Physiologic/Mental is a factor when the individual's diminished physical or
mental capability is due to an inadequate recovery, as the result of restricted or shortened
U-28A, TIN 07-0736, 18 February 2012
28
sleep or physical or mental activity during prolonged wakefulness. Fatigue may
additionally be described as acute, cumulative or chronic. (AFI 91-204)
The MP had recently had a change in his duty schedule where he advanced his duty day
almost 12 hours. He was given 2 days off from the flying schedule to adjust to this new
schedule. (Tab G-18) The day prior to the mishap, the MP was issued four zolpidem
(Ambien) tablets. (Tab DD-11) Ambien is a medication that is approved for use in
aviators as an adjunct to the aircrew fatigue management program. (Tab BB-27 to -28)
The MCP and MOP 1 had just arrived at the deployed location 2 days prior to the mishap
and had shifted 9 hours ahead during that timeframe. These changes in the circadian
rhythm of these three members of the MC could have led to them suffering from acute
fatigue. While this was not likely incapacitating, it is possible that fatigue could have
delayed a necessary response in a situation where a time-critical decision had to be made.
12. FLIGHT SIMULATION
a. Flight Simulator
To simulate the MA flight conditions, the U-28A non-motion flight simulator at Hurlbmi Field,
FL was used. The U-28A simulator allows for multiple emergency procedures (EPs) in multiple
environments to be displayed for both day and night. The terrain around Djibouti and Hurlburt
Field, FL were used to include Ambouli International Airport.
b. MA Profile
The profile began at 10,000 ft MSL, 10 miles south of the airfield, and at 130 IGAS. The profile
simulated a systems check and then went into a modified Max Rate Descent to the west. The
aircraft was on a 360 degree heading, approaching the airfield from the south when the Power
Control Lever (PCL) was pushed up to increase airspeed reaching 180 KIAS. Three miles from
the airfield, the PCL was moved back to the IDLE position, decreasing the power to an idle state,
and at 177 KIAS, the landing gear were lowered. As the landing gear were coming down, the
attitude was lowered slightly to approximately 10 degrees nose low to maintain 170 KIAS while
the gear were in transit. Once there were three green lights on the landing gear indicators, the
pitch was lowered initially to 20 degrees nose low to build up airspeed and then raised to 15
degrees nose low to maintain 220 KIAS in the descent. The descent was started two miles south
of the airfield with a 6,000 fpm descent and a 30 degree left bank turn. The descent rate was
shallowed out to 4,800 fpm, 2,400 fpm, and 3,200 fpm to match the descent profile of the MA to
an altitude of 4,400 ft MSL. The profile included a 5-second level off at 4,400 ft MSL then a
descent down to 3,000 ft MSL where the simulator was frozen so that the current parameters
could be recorded and a starting point could be established at 3,000 ft MSL and 190 KIAS for
further simulations. There was nothing significant to note in the descent from 10,000 ft MSL to
3,000 ft MSL.
Numerous descents from 3,000 ft MSL were attempted to try and best match the final profile of
the MA. Descents with emergencies, without emergencies, and numerous bank angles and pitch
angles were attempted. Through extensive interviews, the experience and expertise of the AlB
U-28A, TIN 07-0736, 18 February 2012
29
members and subject matter experts, the analysis done by Pilatus, and the simulator modeling,
the following scenarios can be ruled out: (Tab HH-15 to -21, JJ-9)
Engine flameout: According to the report produced by the engine manufacturer, Pratt &
Whitney, the engine was operating at the time of impact. (Tab J-39) Taking into
consideration the glide ratio of the U-28A, the high final descent profile of the MA, and
the standard flameout procedures used by U-28A crews, engine flameout can be ruled out
as the cause of the mishap.
Mid-air collision: According to the radar returns, there were no other aircraft in the
vicinity of the MA when the mishap occurred. (Tab M-4 to -18)
Electrical failure: Several electrical failures were duplicated in the simulator to
detennine if any type of electrical failure could either cause or factor into the final
descent profile of the MA. The design ofthe electrical system, the backup systems, and
the instruments of the U-28A prevents anything short of a complete electrical failure
from causing a loss of all flight instruments. A complete electrical failure can be ruled
out due to the data that was able to be retrieved from the EGPWS, which indicates that
electrical power was being supplied to the EGPWS and the other aircraft avionics. (Tab
BB-17to-23)
Aircraft structural integrity failure: No aircraft pieces were found outside of the
immediate impact site.
Pitch Trim: After running a nose down pitch trim runaway scenario, an unrecognized
pitch trim runaway matches the profile flown by the MA but analysis of the pitch trim
actuator by Pilatus showed the pitch trim in a neutral position at impact. (Tab HH-21)
U-28A, TIN07-0736, 18 February 2012
30
Figure 4. MA Descent profile from 2972 ft MSL to impact. (Tab JJ-9)
After ruling out the above malfunctions as improbable, the board looked into what could cause
the MC to put the MA into the aggressive final turn and descent assuming that the MC was
wearing NVGs and that the MP was flying the MA. (Tab V-9.3)
c. Spatial Disorientation
Multiple scenarios were run in the simulator to determine how the MC could have placed the
MA into the final profile. At the beginning of the EGPWS data, the MA is south of extended
runway centerline, heading west, away from the airfield in an extended downwind. The MA was
in a 25 degree right bani( which indicates a possible turn back to final which would be consistent
with the last repotied instructions. The MA then began a turn to the left while at the same time,
increasing the descent rate from around 2,500 fpm to 5,100 fpm in 10 seconds. (Tab JJ-9) In the
simulator, the board considered what could lead to the decision to turn left and examined
potential threats such as hostile fire, another aircraft, or a bird. The turn does not seem to be
aggressive at the beginning, which could indicate that the turn was not in response to a threat.
There were no reports of surface-to-air fire, the radar does not show any other aircraft around the
MA, and a continued turn would not be needed to avoid a bird; therefore, it is unknown what
precipitated the decision to turn left. (Tab M-15 to -18)
A spatial disorientation simulator profile was flown, in which the pilot flying in the left seat
would look out the left pilot's window, simulating an attempt to acquire the runway
U-28A, TIN 07-0736, 18 February 2012
31
environment. While looking out the window, the aircraft would increase in bank angle and
increase the descent rate by pitching down similar to the MA profile. The bank angle was
matched easily on every attempt, but the computed pitch of 36 degrees nose low at impact was
not naturally occurring. (Tab JJ-9) To achieve the 36 degrees nose low, the aircraft yoke had to
be pushed in slightly during the turn, which could be a response to a vestibular illusion by the
MP. Numerous attempts at achieving the flight profile were successful in getting close to the
MA's profile. ·
MSL Vertical Bank Ground
Time Altitude Velocity Angle Speed
16:17:52 2972 -2443 R25 195
16:17:53 2972 -2370 R25 195
16:17:54 2934 -2282 R25·. 194:
16:17:55 2896 -2272 R25 193
..
16:17:56 2810 -2329 R22 190
16:17:57 2810 -2358 R22 190
16:17:58 2766
.
-2414 R19 .. .. 188
16:17:59 2720 -2469 R17 187
16:18:00 2674 -2520 R15 186
16:18:01 2630 -2551 R12 185
16:18:02 2574 -2723 ./ R9 184<
16:18:03 2510 -2856 R6 183
16:18:04 2454 ~2985 ·'·. R4 182'·;
16:18:05 2322 -3299 L9 181
16:18:06 ·.· 2322 -3430 '·.•·.·. L9 I: 181
16:18:07 2252 -3676 L18 180
16:18:08 ·. 2174 -3914 · L27 180':• I
.
16:18:09 2000 -4388 L40 180
16:18:10 .. , , . 2000 .· .... -4602 I . L40 1.·. 180;
16:18:11 1894 -5107 L45 179
16:18:12 I. 1770 -5741' L48 179.
16:18:13 1632 -6493 L51 178
16:18:14 1302 -7835 L54 1741.
16:18:15 1302 -8323 L54 174
16:18:16 1104 -9358 L55 172
16:18:17 890 -10389 L55 170
16:18:18 434 -11752 L55 165
Table 6. MA Descent profile from 2972 ft MSL to impact from EGPWS. The red/bold numbers
show when EGPWS gave aural warnings. 1618:11-12 indicates a SINK RATE caution and
1618:14-15 indicates a PULL UP warning. (Tab JJ-9)
U-28A, TIN 07-0736, 18 February 2012
32
The EGPWS indicates two alerts that were displayed in the cockpit to warn the MC of the
descent rate and approaching terrain. (Tab JJ-9) The first alert, a "Sink Rate, Sink Rate" aural
caution, occurred approximately 7 seconds prior to impact. (Tab JJ-9) The second alert occurred
approximately 4 seconds prior to impact and was a "Pull Up, Pull Up" aural warning. (Tab JJ-9)
In the simulator, a 2-second delay was added by the pilot to signify the average time it takes the
pilot flying to look in the cockpit from outside, determine if the sink rate is excessive and react.
The question was, after each of the alerts, if the MC attempted to recover the MA, could it have
been saved? While matching the MA's profile, a "Sink Rate, Sink Rate" caution was given in
the simulator at 1 ,800 ft MSL and on all occasions, the aircraft leveled off by 1,000 ft MSL after
applying the 2-second delay. If corrective action was taken after the Sink Rate caution, the
aircraft could have been recovered. While matching the MA's profile and ignoring the Sink Rate
caution, a "Pull Up, Pull Up" warning was given at 1,300 ft MSL, a 2-second delay was added
and the aircraft leveled off by 300 ft MSL which would have been 100 ft above the teiTain. Had
corrective action been taken after hearing the Pull Up warning, the MA could have been saved.
Any delay, and the aircraft could not have been recovered. The backpressure on the yoke to pull
the airplane out of the dive in the simulator was within tolerances and power was applied after
the pull up to climb away from the ground.
13. GOVERNING DIRECTIVES AND PUBLICATIONS
a. Primary Operations Directives and Publications
(1) AFI 11-202, Volume 3, General Flight Rules, 22 October 2010
(2) AFI 11-2U28, Volume 3, Flying Operations: U-28 Operations Procedures, 27
January 2009
(3) AFI 51-503, Aerospace Accident Investigations, 26 May 2010
b. Maintenance Directives and Publications
(1) Code of Federal Regulations, Title 14: Aeronautics and Space, Part 39:
Airworthiness Directives
c. Medical Directives and Publications
(1) AFI 48-123, Medical Examinations and Standards, 24 September 2009
(2) AFI 44-170, Preventive Health Assessment, 10 December 2009
(3) AFI 91-204, Safety Investigations and Reports 24 September 2008 (listing of
Department of Defense Human Factors Analysis and Classification System)
d. Known or Suspected Deviations from Directives or Publications.
According to the AFI 11-2U28, Volume 3, paragraph 6.18.1, "Any training or operational
missions planned when the lunar illumination is forecast to be less than 10% during the mission
will require an additional level of ORM." (Tab BB-3 to -4) The ORM worksheet does not reflect
that the crew applied an additional level of ORM to the sortie. (Tab K-11 to -12) On the back of
the ORM worksheet; there is a place for the MC to request approval for flying in a low
U-28A, TIN 07-0736, 18 February 2012
33
illumination condition. On the MC's ORM worksheet, this approval was not requested .nor \Vas
it approved. (Tab K-12)
14. ADDITIONAL AREAS OF CONCERN
Not applicable. ·
15. SIGNATURE AND DATE
BrigadierGeneral1 USAF
President, Accident Investigation Board
U-28A, T!ND7-0736, 18February 2012
34
STATEMENT OF OPINION
U-28A, TIN 07-0736 ACCIDENT
18 FEBRUARY 2012
Under 10 U.S.C. § 2254(d), the opinion ofthe accident investigator as to the cause of, or the factors
contributing to, the accident set forth in the accident investigation report, if any, may not be considered
as evidence in any civil or criminal proceeding arising from the accident, nor may such information be
considered an admission of liability of the United States or by any person referred to in those conclusions
or statements.
1. OPINION SUMMARY
On 18 February 2012, at approximately 1918 local time (L), a United States Air Force U-28A
aircraft, tail number 07-0736, crashed five nautical miles (NM) southwest of Ambouli
International Airport, Djibouti. This aircraft was assigned to the 34th Special Operations
Squadron, 1st Special Operations Wing, Hurlburt Field, FL, and deployed to the 34th
Expeditionary Special Operations Squadron, Camp Lemonnier, Djibouti. The aircraft was
destroyed and all four aircrew members died instantly upon impact.
The mishap aircraft (MA) departed Ambouli International Airport, Djibouti at 1357L, to
accomplish a combat mission in support of a Combined Joint Task Force. The MA proceeded to
the area of responsibility (AOR), completed its mission in the AOR and returned back to
Djiboutian airspace at 1852L arriving overhead the airfield at 191 OL to begin a systems check.
The MA proceeded south of the airfield at 10,000 feet (ft) Mean Sea Level (MSL) for I 0 NM
then turned to the North towards the airfield, accomplished a systems check and requested entry
into the pattern at Ambouli International Airport. This request was denied due to other traffic,
and the MA was directed to proceed to the west and descend by Air Traffic Control (A TC). The
MA began a left descending turn to the west and was directed by ATC to report final. The
mishap crew (MC) reported they were passing through 4,000 ft MSL and would report when
established on final approach. The MA, continuing to descend, initiated a right turn then
reversed the turn entering a left turn while continually and smoothly increasing bank angle until
reaching 55 degrees prior to impact. Additionally, the MA continued to steadily increase the
descent rate until reaching 11,752 ft per minute prior to impact. The MA impacted the ground at
approximately 1918L, 5 NM southwest of Ambouli International Airport, Djibouti.
2. DISCUSSION OF OPINION
I find by clear and convincing evidence that the cause of the mishap was unrecognized spatial
disorientation. Additionally, I find by a preponderance of the evidence that failing to crosscheck
and ignoring the "Sink Rate" caution substantially contributed to the mishap. With no
eyewitness accounts, surviving aircrew members, emergency radio calls or "black box"
recordings, the specific reason for the spatial disorientation cannot be determined. The board
looked at three potential scenarios that could have caused the mishap:
U-28A, TIN07-0736, 18 February 2012
35
Scenario 1: Loss of controlled flight due to over aggressive aircraft handling. The final left
hand turn approached the maximum allowed bank angle of the aircraft. However, extensive
simulator recreation of the flight, based on recovered Enhanced Ground Proximity Warning
System (EGPWS) and Blue Force Tracker (BFT) data, indicated that at no time did the MA
depart controlled flight. Furthermore, through interviews with numerous crewmembers, who had
previously flown with the MP and MCP, it was evident that aggressive turns at low altitude and
overly aggressive aircraft handling were not standard for the MA pilots. Specifically, the MP
was known to be a conservative pilot who was always teaching less experienced pilots to remain
aware of aircraft performance, practice energy management and know how to use aircraft
systems and instruments to maintain situational awareness. It is my opinion that the MC did not
intentionally execute an aggressive, descending turn at low altitude.
Scenario 2: Loss of aircraft control and/or situational awareness due to aircraft malfunction.
The board analyzed the effects of malfunctioning flight control surfaces and compared that to the
flight profile. Based on simulator recreation, it was determined a runaway pitch trim would
provide a flight profile similar to the profile the MA flew based on EGPWS and BFT data. If
this malfunction was not recognized in a timely manner it would have made aircraft recovery
difficult. However, engineering analysis of pitch trim actuators and all other flight control
surfaces indicated no mechanical discrepancy. Additionally, the board analyzed the failure of
multiple electrical inputs to flight instruments in an attempt to remove all critical flight
information from the flight crew. Due to multiple redundancies, in order to deny the crew of all
aircraft attitude reference, this would require the loss of all electrical power. However, since
data was recorded on the EGPWS until impact, which required electrical power, the MA could
not have lost all electrical power. It is my opinion that the MA did not have any mechanical
problems that caused the mishap.
Scenario 3: The MA was descending to the west of Ambouli International Airpmi, Djibouti on
a zero illumination night with the only significant cultural lighting off the tail of the aircraft.
Other crews described this area as a "black hole". The MC began a turn from this area of
minimal cultural lighting toward an area of significantly greater cultural lighting and from an
area with an elevation of 265 ft MSL to Ambouli International Airport, with an elevation of 49 ft
MSL. The MC had Night Vision Goggles (NVGs) and it was standard practice to wear the
NVGs during night operations. With the use of NVGs, the field of view is limited and depth
perception is reduced. The EGPWS and BFT data indicates the aircraft entered a left hand turn
and consistently and smoothly increased bank angle and descent rate. The MC was provided
both visual and aural "Sink Rate" and "Pull Up" alerts due to MA descent rate and proximity to
terrain. While it is not uncommon for U-28A crews to disregard a "Sink Rate" alert if visual
with the terrain and the aircraft is in a safe position, it is uncommon to get or disregard a "Pull
Up" alert, which was received 4 seconds prior to impact. This same EGPWS data depicts no
corrective action was initiated prior to impact. A crew that was cognizant of its altitude, attitude
and sink rate would have immediately leveled the wings and increased pitch and power as
described in the U-28A Pilot's Operating Handbook. (Tab BB-16 to -17) Failure to immediately
react to the "Pull Up" warning indicates a crew that does not take action because it believes the
aircraft is in a position that does not warrant a "Pull Up" warning. There was a cognitive
disconnect with the MC' s perception of the flight envelope they were operating in and the alerts
provided by the aircraft.
U-28A, TIN 07-0736, 18 February 2012
36
Spatial Disorientation, as defined in Air Force Instruction 91-204, is a failure to correctly sense a
position, motion or attitude of the aircraft or of oneself within the fixed coordinate system
provided by the surface of the earth and the gravitational vertical. Spatial Disorientation (Type
1) Unrecognized is a factor when a person's cognitive awareness of one or more of the following
varies from reality: attitude; position; velocity; direction of movement or acceleration. Proper
control inputs are not made because the need is unknown. The MA was in a high bank turn with
an excessive nose down attitude that resulted in a high descent rate in close proximity to the
ground that was incongruent with normal aircraft operation. Extensive flight recreations of this
profile in the simulator allowed the board to successfully recover the aircraft when corrective
action was taken. This includes delaying corrective action until after the "Sink Rate" and "Pull
Up" alerts were received. There was sufficient time to react to these alerts if the MC was aware
of the situation the MA was in; therefore, failure to accurately react to these alerts is indicative of
a lack of cognitive awareness of the attitude, altitude and sink rate of the aircraft as experienced
by a pilot that was spatially disoriented.
Unrecognized spatial disorientation can be difficult to react to, even with aural alerts, because the
aural alerts are counter to the pilot's perception of reality. The pilot must interpret the alerts,
which are inconsistent with his perceptions, and attempt to reconcile them with instrument or
visual reference. Action to save the MA after receiving the aural "Pull Up" warning was
required within two seconds; any action taken after that would not have saved the MA and might
not be reflected in the EGPWS data. As previously mentioned, a crew that was aware of its
altitude, attitude and sink rate would have immediately leveled the wings and increased pitch and
power. While there would be some delay between flight control input and displacement of the
aircraft coupled with EGPWS recording latency, there is no indication that corrective action was
taken. The evidence demonstrates that the MC did not recognize the position of the aircraft and,
as a result, failed to take appropriate corrective actions. The only plausible reason for the MC
not recognizing the situation or reacting to aural alerts is the cognitive disconnect associated with
spatial disorientation. Therefore, I find by clear and convincing evidence that the mishap was
caused by unrecognized spatial disorientation.
I find two additional human factors that substantially contributed to the mishap. The first of
these is "Caution/Warning Ignored." It is apparent that the MC disregarded or ignored the "Sink
Rate" caution. It would not have been unusual to receive this caution during a tactical arrival,
particularly if they believed they were visual with the terrain. The MC had sufficient time to
react to the "Sink Rate" caution, and there is no evidence showing that they attempted to do so.
Therefore, I have concluded by a preponderance of the evidence that the MC disregarded the
"Sink Rate" caution, which substantially contributed to the mishap.
The second substantially contributing human factor is a failure in "Cross-Monitoring
Performance." As previously mentioned, it is not uncommon for U-28A crews to disregard a
"Sink Rate" caution if visual with the terrain and the aircraft is in a safe position. However, the
recommended altitude to the west of Ambouli International Airport is 1300 ft MSL and the "Sink
Rate" caution was received at 1800 ft MSL. (AFI 11-202V3, paragraph 5.14.3) If the MC was
aware of the attitude, altitude and sink rate of the aircraft, they should have made a control input
at that time in order to level off at 1300 ft MSL. The MC could have cross checked their
U-28A, TIN 07-0736, 18 February 2012
37
instruments to verify ~hey were in a safe position in order to purposely disregard the "Sirik Rate"
caution. If they had, they would have :reaiized the attitude and sink rate at that altitude put the
MA into an unsafe position requiring corrective action. Therefore, I find by a preponderance of
the evidence that failure to cross check was substantially contributing to this mishap.
3. CONCLUSJ[ON
The MC never1ost control of the aircraft; there' ate no indications of mechanical malfunction;
and there are no indications the crew took any actions to control or arrest the descent rate and
nose down attitude. I find that the clear and convincing evidence indicates the cause of the
mishap was unrecognized spatial disorientation. Additionally, I find by a preponderance of the
evidence that failing to cross-check and ignoring the "Sink Rate"' caution substantially
contributed to the mishap.
General, USAF
President; Accident Investigation Board
U-28A, T/N0?-0736, 18 Februmy2012
38
INDEX OF TABS
SAFETY INVESTIGATOR INFORMATION ............................................................................................................ A
NOTUSED .................................................................................................................................................................. B
NOTUSED .................................................................................................................................................................. C
MAINTENANCE REPORT, RECORDS, AND DATA .............................................................................................. D
NOT USED .................................................................................................................................................................. E
WEATHER AND ENVIRONMENTAL RECORDS AND DATA .............................................................................. F
PERSONNEL RECORDS ............................................................................................................................................ G
EGRESS, IMP ACT, AND CRASHWORTHINESS ANALYSIS ............................................................................... H
DEFICIENCY REPORTS ......................................................................................... , ................................................... I
RELEASABLE TECHNICAL REPORTS AND ENGINEERING ANALYSIS .......................................................... J
MISSION RECORDS AND DATA ............................................................................................................................. K
FACTUAL PARAMETRIC, AUDIO, AND VIDEO DATA FROM ON-BOARD RECORDERS ............................ L
DATA FROM GROUND RADAR AND OTHER SOURCES .................................................................................. M
TRANSCRIPTS OF VOICE COMMUNICATIONS .................................................................................................. N
ANY ADDITIONAL SUBSTANTIATING DATA AND REPORTS ......................................................................... O
DAMAGE SUMMARIES ............................................................................................................................................. P
AlB TRANSFER DOCUMENTS ................................................................................................................................ Q
RELEASABLE WITNESS TESTIMONY .................................................................................................................. R
RELEASABLE PHOTGRAPHS, VIDEOS, AND DIAGRAMS ................................................................................. S
INDIVIDUAL FLIGHT RECORDS AND ORDERS (not INCLUDED IN TAB G) .................................................. T
AIRCRAFT MAINTENANCE RECORDS (NOT INCLUDED IN TAB D) .............................................................. U
WITNESS TESTIMONY AND STATEMENTS ........................................................................................................ V
NOT USED ................................................................................................................................................................. W
STATEMENTS OF INJURY ORDEATH .................................................................................................................. X
DOCUMENTS APPOINTING AIB ............................................................................................................................. Y
PHOTOGRAPHS (NOT INCLUDED IN TAB s) ....................................................................................................... Z
U-28A, TIN 07-0736, 18 February 2012
39
FLIGHT DOCUMENTS ........................................................................................................................................... AA
GOVERNING DOCUMENTS AND REGULATIONS ............................................................................................ BB
TECHNICAL REPORTS RELEASE APPROV AL ................................................................................................... CC
ADDITIONAL PERSONNEL RECORDS ............................................................................................................... DD
INTERIM SAFETY BOARD (ISB) INTERVIEWS .................................................................................................. EE
FACT SHEETS .......................................................................................................................................................... FF
LIFE SUPPORT DOCUMENTS .............................................................................................................................. GG
TECHNICAL REPORTS .......................................................................................................................................... HH
AlB MEMBER MEMORANDA FOR RECORD (MFR) ............................................................................................ IT
FLIGHT PATH DOCUMENTS ................................................................................................................................... JJ
U-28A, TIN 07-0736, 18 February 2012
40