Pilot Debrief

GRUMMAN AMERICAN AVN. CORP. AA-5 near Rockmart, GA — 2024-09-04

Final reportERA24FA365
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Date
2024-09-04
Location
Rockmart, GA, USA
Airport
PUJ
Aircraft
GRUMMAN AMERICAN AVN. CORP. AA-5
Registration
N9659L
Category
Airplane
Highest injury
Fatal
Fatalities
2
Phase of flight
Maneuvering

Probable cause

A total loss of engine power for undetermined reasons. Also causal was the flight instructor’s failure to maintain adequate airspeed during the forced landing attempt, which resulted in exceedance of the airplane’s critical angle of attack and an aerodynamic stall.

NTSB narrative

The flight instructor was conducting a dual instructional flight with the student pilot. The accident flight was the flight instructor’s third flight in the airplane make and model and the student pilot’s second dual instructional flight. Recorded flight track data showed that, after departure, the airplane remained within 15 miles of the airport and proceeded in maneuvering flight consistent with a private pilot training profile. During the final 5 minutes of the flight, the airplane turned to and maintained a northeasterly heading for about 4 minutes, followed by a turn to the east, and then to the north. The last recorded ADS-B data showed a gradual left turn about 150 ft above the ground, with a groundspeed of about 74 to 78 mph. The stall speed for the airplane with flaps up and 20° of bank was about 64 mph (indicated airspeed). The last recorded ground track location was about 250 ft east-southeast of the accident site. The airplane impacted wooded terrain at a steep, nose-low attitude, consistent with an aerodynamic stall. The flight instructor and the student pilot were fatally injured and there were no known witnesses to the accident. A postaccident examination of the flight controls did not reveal evidence of a preexisting mechanical malfunction or failure. Both wing fuel tanks were breached, and the airplane’s fuel state at the time of the accident could not be determined from available information. Although no anomalies were found during the examination of the engine and fuel system, the propeller showed no signs of powered rotation at impact. Additionally, the temperature and dew point near the accident site were conducive to the formation of serious carburetor icing at glide (idle) power. Although the carburetor heat knob was found full forward (cold) position, it was partially broken off and the portion of the instrument panel surrounding the knob showed impact deformation; accordingly, the preaccident use of carburetor heat couldn’t be determined. At the time of the accident, the flight instructor did not hold a current Federal Aviation Administration (FAA) -issued medical certificate; however, based on the accident circumstances, the instructor’s impairment or incapacitation from a medical issue was unlikely. Postmortem toxicological testing results indicated that the student pilot had used one or more cannabis products and may have been experiencing associated impairing psychoactive effects during the flight. However, considering the accident circumstances, the student pilot’s limited baseline skill and experience, his limited flight safety responsibilities on the accident flight, and the presence of the flight instructor, it is unlikely that effects of his cannabis use contributed to the accident. Additionally, the low levels of ethanol detected in vitreous fluid indicated that some or all of the detected ethanol may have been from postmortem production rather than alcohol consumption; accordingly, ethanol was also unlikely to have contributed to the accident. The flight track data showed that, during the final minute of the flight, the airplane passed near the end of two fields before it turned over a wooded area toward a clearing, consistent with an attempt to glide the airplane to an area to perform a forced landing. The airplane’s relatively low speed during these final moments of the flight, coupled with the lack of powered rotational signatures observed on the propeller after the accident, suggest that the airplane’s engine may have lost power, though no evidence of any mechanical malfunction or failure of the engine were observed during the postaccident wreckage examination. The airplane’s fuel state and the flight instructor’s use of carburetor heat at the time of the accident could not be determined based on the available information. It is likely that, during this attempted approach, the flight instructor allowed the airplane’s airspeed to decay, which resulted in the exceedance of the airplane’s critical angle of attack and an aerodynamic stall.

Analysis

Primary failure mode
Loss of control

NTSB coding

Evidence available

  • ADS-B / radar
  • Photos
  • 22 docket documents
View NTSB final reportView NTSB docket

Docket documents22

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