Accident Overview
On 22 June 2018, at 1133 hours local time, an A-29 aircraft (tail number PT-ZNV-221) crashed after delivering a Guided Bomb Unit (GBU)-12 weapon on the Red Rio Bombing Range, part of the White Sands Missile Range, New Mexico. The aircraft was owned by Embraer, operated and maintained by the Sierra Nevada Corporation, and also operated by the 586th Flight Test Squadron (FLTS), Holloman Air Force Base, New Mexico. The mission was a continuation training sortie flown in support of the Light Attack Experiment Phase II.
Sequence of Events
The aircraft departed Holloman Air Force Base at 1103 local time. The mission proceeded without incident until the first weapon delivery, a GBU-12 release from the left outboard pylon. The mishap pilot planned and attempted to execute a right 180-degree turn after the weapon delivery. The pilot exacerbated the aircraft's right rolling tendency, caused by the GBU-12 release, by making right aileron and rudder inputs while applying 1.47 positive g's. This resulted in a rapid roll to the right followed by an uncontrolled spiral dive. The mishap crew made four unsuccessful recovery attempts before initiating the ejection sequence below the A-29 Flight Manual recommended minimum altitude for uncontrolled flight.
Crew and Injuries
The mishap crew consisted of a mishap pilot, a United States Naval aviator with F/A-18 experience, and a mishap weapon systems officer, a United States Air Force navigator with a special operations background in the U-28A. The weapon systems officer ejected with minor injuries, while the pilot died instantly upon impact after a delayed ejection initiation. The aircraft was destroyed.
Findings
The Accident Investigation Board (AIB) President found, by a preponderance of the evidence, that the cause of the mishap was the mishap pilot's overcontrol of the aircraft causing an inadvertent entry into an uncontrolled spiral dive, combined with his failure to apply adequate recovery control inputs. Additionally, the AIB President found that a specific cause of the pilot's death was delayed initiation of the ejection sequence by the mishap crew, not in accordance with established procedures.
The AIB President also found that wrong choice of action by the mishap crew in attempting a 180-degree turn maneuver, without compensating for asymmetry of weapon release at low airspeed, substantially contributed to the mishap. In addition, fixation, critical information not communicated between the crew during the recovery, and operation of the ejection seat selector as directed in SINGLE mode substantially contributed to the fatality.
Probable Cause
The probable cause, as determined by the AIB President, was the mishap pilot's overcontrol of the aircraft causing an inadvertent entry into an uncontrolled spiral dive, combined with his failure to apply adequate recovery control inputs.