IMPALA MB-326M N155TP accident near Edwards, California

Probable cause

The flight crew’s restricted rudder inputs while in an inverted spin that precluded spin recovery.

NTSB analysis

The flight instructor and the pilot receiving instruction reported that the intent for the flight in the light military jet trainer was spin data collection. Before the accident, they performed several maneuvers, including a left inverted spin, without incident. From an altitude of about 22,000 ft mean sea level (msl), the pilot receiving instruction made flight control inputs that placed the airplane in a second inverted left spin. After three revolutions, he attempted to recover from the spin to no avail. The flight instructor assumed control of the airplane and attempted a recovery. However, the spin rate and negative G forces continued to increase and pushed the instructor out of his seat. The flight instructor could only touch the right rudder with his toes and was not able to apply sufficient right rudder control input to recover from the spin. Unable to recover and reaching the ejection decision altitude, he ordered ejection. The pilot receiving instruction and the flight instructor ejected, and the airplane descended to ground impact.

Postaccident examination of the airplane did not reveal evidence of any mechanical anomalies that would have precluded normal operation. The pilot receiving instruction reported that he reviewed the accident with the operator’s chief pilot while he was seated in a similar type of airplane. While seated normally, he was able to move the rudder pedals to the full left and right deflection. However, the clearance between his shins and the instrument panel was reduced in a simulated negative G scenario; his range of motion was very limited as he could only use his toes to activate the rudder pedals. He further reported having difficulties applying rudder deflection during the recovery of both inverted spins on the day of the accident due to his shins contacting the instrument panel. It is likely that the negative G forces during the inverted spin pushed the pilot receiving instruction’s shins into the instrument panel, which restricted his ability to fully deflect the rudder pedals. Further, when the flight instructor took control, he was also unable to fully deflect the rudder pedals due to the high negative G forces pushing him out of his seat. Therefore, the flight crew was unable to recover from the inverted spin and had to eject from the airplane.

Text from the NTSB. Open the NTSB docket for WPR21LA123 for the full record.