Amateur-built ZODIAC CH 601 HD N401 accident near Ama, Louisiana

Probable cause

The pilot's failure to maintain adequate airspeed and his exceedance of the airplane's critical angle of attack following a loss of engine power for reasons that could not be determined based on available evidence, which resulted in an aerodynamic stall and left spin.

NTSB analysis

The private pilot was conducting a local flight in the experimental, amateur-built airplane. GPS data indicated that, during the takeoff roll, the airplane had a maximum groundspeed of 84 knots. The groundspeed varied between 45 and 96 knots as the airplane turned to a southwesterly heading after departure. About 1 minute 18 seconds after takeoff, the airplane made a right turn toward the northwest. The last recorded data point showed the airplane at an altitude of 66 ft and a groundspeed of 15 knots. When the airplane failed to return to the airport, a search was initiated. The wreckage was found the next day. The airplane impacted terrain in a thickly wooded area in an 80°-nose-down attitude. The airplane's nose section was skewed to the right, the right wing was leading, the left wing was trailing, and the empennage was bent down to the left, consistent with the airplane being in a left spin following an aerodynamic stall.

Examination of the propeller assembly revealed indications of little or no rotation at impact. An engine examination revealed no mechanical malfunctions or failures that would have precluded normal operation. The weather conditions were conducive to serious icing at glide power, but the airplane was operating at takeoff power. Therefore, it cannot be said with certainty that the carburetor accumulated ice and caused a loss of engine power. Based on the GPS data and wreckage examination, it is likely that the pilot failed to maintain adequate airspeed and exceeded the airplane's critical angle of attack following a loss of engine power for reasons that could not be determined based on available evidence, which resulted in an aerodynamic stall and subsequent left spin.

The pilot's autopsy identified significant coronary artery stenosis and evidence of a previous heart attack. The pilot's previous heart attack and significant coronary artery stenosis placed him at risk for an acute cardiac event such as an arrhythmia or ischemia that would have caused chest pain, shortness of breath, palpitations, or fainting. If such an event occurred, the acuteness of the accident would have precluded identifying evidence of it at autopsy. Although acute incapacitation could have occurred, this investigation was unable to determine whether the pilot's cardiovascular disease contributed to the accident. Additionally, the evidence of a loss of engine power does not support a medically incapacitating event.

Text from the NTSB. Open the NTSB docket for CEN15FA426 for the full record.