Accident Overview
On 18 February 2012, at approximately 1918 local time, a United States Air Force U-28A aircraft, tail number 07-0736, crashed five nautical miles southwest of Ambouli International Airport, Djibouti. The aircraft was destroyed and all four aircrew members died instantly upon impact. The aircraft was assigned to the 34th Special Operations Squadron, 1st Special Operations Wing, Hurlburt Field, Florida, and was deployed to the 34th Expeditionary Special Operations Squadron, Camp Lemonnier, Djibouti.
Flight Sequence
The mishap aircraft departed Ambouli International Airport at 1357 local time for a combat mission in support of a Combined Joint Task Force. It proceeded to the area of responsibility, completed its mission, and returned to Djiboutian airspace at 1852 local time. The aircraft arrived overhead the airfield at 1910 local time to begin a systems check. It then proceeded south of the airfield at 10,000 feet Mean Sea Level for 10 nautical miles, turned north toward the airfield, accomplished the systems check, and requested entry into the traffic pattern. The request was denied due to other traffic, and air traffic control directed the aircraft to proceed west and descend. The mishap crew reported passing through 4,000 feet MSL and would report when established on final approach. While continuing to descend, the aircraft initiated a right turn, then reversed into a left turn with a continuously and smoothly increasing bank angle to 55 degrees prior to impact. The descent rate steadily increased to 11,752 feet per minute. The crew received aural "Sink Rate" and "Pull Up" alerts with no apparent corrective action. The aircraft impacted the ground at approximately 1918 local time.
Findings
The official investigation determined that the crew never lost control of the aircraft, and there were no indications of mechanical malfunction. The crew did not take any actions to control or arrest the descent rate and nose-down attitude. Evidence indicated that the crew did not recognize the aircraft's position and failed to take appropriate corrective actions. The Board President found that the clear and convincing evidence indicated the cause of the mishap was unrecognized spatial disorientation. Additionally, by a preponderance of the evidence, failing to crosscheck and ignoring the "Sink Rate" caution substantially contributed to the mishap.