The Engine Power Increased From 36% To 92% N1 During The Last Five Seconds Of Recorded Data

Location: Bridgeport, Texas Accident Number: CEN23FA160
Date & Time: April 19, 2023, 18:37 Local Registration: N1390A
Aircraft: Aero Vodochody L-139 Aircraft Damage: Substantial
Defining Event: Collision during takeoff/land Injuries: 2 Serious
Flight Conducted Under: Part 91: General aviation - Instructional

Analysis: The pilot and the flight instructor departed in the tandem-seat airplane for an instructional flight. Upon arriving at the destination airport, a low approach was performed. The airplane did not land, and it climbed out. During the second approach, a no-flap landing was to be performed. While on a straight-in approach about one mile from the runway, the flight instructor reported the airplane encountered a “large flock of large birds.” The flight instructor, who was not flying at the time, was looking for possible bird strike damage sustained to the wings, the engine, and the empennage. While looking for the possible bird strike damage, he felt the sink rate increasing. He then initiated a go-around.

As the nose of the airplane started to rise for the go-around, the airplane impacted the top of a large tree. After the airplane impacted the tree, the airplane landed upright and traveled on the ground before coming to rest partially inside of a barn. The airplane sustained substantial damage to the fuselage, both wings, and the empennage.

The pilot was unable to recall what occurred during the accident flight. No signs of bird remains were observed on the airframe or in the engine. Data from an engine monitoring unit showed the engine performance parameters were normal during the accident flight. The engine power increased from 36% to 92% N1 during the last five seconds of recorded data.

An airplane performance study revealed that after the airplane performed a low approach to runway 18, the engine power was reduced during the subsequent climb out and the throttle was not increased until the airplane was on the final approach and approximately 124 ft above field elevation.

It is likely that the pilot failed to maintain a stabilized approach path due to her distraction while looking for possible bird strike damage. This distraction resulted in her allowing the airplane to impact a tree. It is likely that the flight instructor failed to initiate timely remedial action as he was also distracted while looking for possible bird strike damage.

Toxicological testing of the pilot’s postaccident specimens indicated that she had used amphetamine. According to the FAA, amphetamine is a “do not issue/do not fly” medication. Amphetamine use can adversely affect cognition, impulse control, perception of risk, and judgment/decision-making. Medical conditions for which amphetamine may be used, such as attention-deficit/hyperactivity disorder or narcolepsy, can be impairing. There was no specific indication in reviewed records that the pilot had such a condition; however, this possibility cannot be excluded.

Toxicological testing also detected phenylpropanolamine in the pilot’s urine, which is a minor metabolite of amphetamine. The pilot’s amphetamine level does not predict specific impairing effects. Based on the available evidence, the contribution of the pilot’s amphetamine use to the accident cannot be determined.

Probable Cause and Findings: The National Transportation Safety Board determines the probable cause(s) of this accident to be -- The pilot’s failure to maintain a stabilized approach path while checking for possible bird strike damage that resulted in a delayed go-around attempt and a collision with terrain. Contributing to the accident was the flight instructor’s distraction while looking for possible bird strike damage during the approach and his delayed remedial action.

FMI: www.ntsb.gov