The Air Force has determined that a Navy pilot flying an A-29 Super Tucano as part of a June 2018 test flight over-controlled the aircraft and failed to apply adequate recovery control inputs, resulting in a fatal crash at White Sands Missile Range, New Mexico.

Air Force Materiel Command (AFMC) released an Accident Investigation Board (AIB) report Feb. 22 detailing the cause of the accident that killed Navy Lt. Christopher Short during Phase II of the service’s light attack experiment.

Embraer and Sierra Nevada Corps’ A-29 Super Tucano Photo: Embraer.

Short, who was an experienced F/A-18 Super Hornet pilot, was flying an Embraer/Sierra Nevada Corp.  [SNC] A-29 turboprop aircraft operating from Holloman Air Force Base, New Mexico, on June 22, 2018. The mission was uneventful until the crew dropped a GPU-12 500-pound laser-guided bomb on the Red Rio Bombing Range. Short planned and attempted to make a right 180-degree turn after the bomb delivery, but apparently did not properly account for the lighter weight.

“By turning too sharply at low airspeed after release of a practice bomb, the aircraft entered an uncontrolled spiral dive,” AFMC said in a statement. Per the accident report: “Insufficient control inputs by the [mishap pilot] resulted in an ever-tightening downward spiral until ground impact, approximately 28 seconds after weapons release.”

The AIB also found that Short attempted four unsuccessful recovery attempts before beginning the ejection sequence, but by that point, the aircraft had sunk below the recommended minimum altitude for uncontrolled flight, preventing the parachute from fully inflating before impact. That was the direct cause of Short’s death, according to the report.

A second crewmember – an Air Force weapon systems officer – was able to eject with minor injuries, while Short was killed upon impact. This was the two officers’ first A-29 flight without an instructor on board and their first flight together.

The report found no evidence of any structure or system issues that could have led to the mishap. The engine and flight controls all appeared to be working normally. Nor was there any evidence that weather was a factor.

However, the report notes that the A-29 aircrews were flying under outdated guidance for using the ejection sequence selector in the “aft” mode. Martin-Baker manufactured the ejection seats in 2015 after modifying them to be operated safely in three modes, but at the time of the accident, not all of the seats had been modified and Embraer had not released updated guidance. The “single” mode that the aircraft was operating with required that the two crew members initiate the ejection sequence separately.

Had the mishap crew been able to fly in the “aft” mode, the pilot’s ejection would have been activated automatically less than a second after the mishap weapon systems officer escaped, “which would have been 2.5 seconds earlier than when [Short] pulled his ejection seat handle, increasing the likeliness of survival,” the report said.

The two crewmembers also failed to properly communicate critical information during the recovery, which also contributed to the fatal nature of the accident.

The test flight was being performed in the second phase of the Air Force’s light attack experiment, where it conducted flight tests of the A-29 and Textron Aviation’s [TXT] AT-6 Wolverine turboprop to potentially serve as off-the-shelf light attack and close-air support platforms in permissive environments. The Air Force ceased performing flight tests following the fatal accident over White Sands, and in February officials confirmed that the experiment would be postponed for the foreseeable future. (Defense Daily, Feb. 1)