Cessna 421 N977SM accident near Lake City, Florida

Probable cause

A landing gear collapse following an aborted takeoff due to degraded climb performance for reasons that could not be determined.

NTSB analysis

The pilot reported that, just after rotation during takeoff, he began to accelerate the airplane to 120 knots. About 20 ft above the runway, he noticed that the airplane’s airspeed and altitude started to decrease, though he reported no issues with either engine. Assessing the length of runway remaining, the pilot chose to abort the takeoff and lowered the landing gear using the normal method. The airplane touched down on the runway before the gear was fully extended, and the landing gear collapsed. The airplane came to rest upright about 1,000 ft before the end of the runway and incurred substantial damage to the airplane’s wings. The pilot stated that there was nothing mechanically wrong with the landing gear, which operated satisfactorily during recovery of the airplane using the emergency extension system.

The departure runway was about 8,000 ft long. The airplane’s flight manual indicated that, given the airplane’s gross weight near its maximum and the environmental conditions present at the time of the accident, a minimum of 3,100 ft was required to accelerate, rotate, and climb to 50 ft; however, flight track data was not available to determine the maximum altitude the airplane reached during the takeoff or the point at which the pilot decided to abort the takeoff.

The pilot attributed the loss of airspeed and altitude to a microburst during takeoff. Review of weather conditions revealed that a quasi-stationary front passed through the area around the time of the accident with a resulting slight wind shift; however, there was no significant wind shear associated with the front. Additionally, no convective echoes associated with microbursts or outflow boundaries were detected in radar data or satellite imagery, and recorded weather observations did not detect any strong gusting winds until well after the accident. Thus, there was no available evidence to support that wind shear or microburst conditions existed at the time of the accident.

Although a reason for the airplane’s degraded climb performance could not be determined, its operation near the maximum gross weight and the ambient temperature at the time of the accident were likely factors. Any delay in the pilot’s recognition of the airplane’s reduced performance and aborting the takeoff would have resulted in the airplane continuing about 200 additional feet along the runway every second.

Text from the NTSB. Open the NTSB docket for ERA24LA041 for the full record.