WPR24FA196 · Lockheed 12A

The accident flight was conducted before a Father’s Day event to prepare for a planned three-airplane formation flight later that day. During the morning briefing, the pilot and co-pilot were assigned to the accident airplane. A representative of the operator believed that the co-pilot extended the flaps during a functional test as part of the preflight inspection. Ground crew members subsequently observed the flaps extended during engine start and warned the flight crew using hand and arm signals; however, the flight crew did not acknowledge the warning. Witness observations indicated that the flaps remained fully extended during taxi and takeoff, and video evidence showed that the flaps remained extended during the initial climb.

The operator reported that crews commonly used reduced engine power on hot days to reduce engine oil temperatures and engine noise. After takeoff, the airplane climbed to approximately 200 to 300 ft above ground level (agl); it then pitched up, turned left, and entered a nose-down descent before impacting terrain. A postcrash fire ensued.

A video study determined that both engines continued to operate until impact and that their speeds ranged from approximately 1,978 rpm to 2,098 rpm, somewhat below the 2,200- to 2,300-rpm takeoff speed.

The pilot had cardiovascular disease, including moderate coronary artery disease, an implanted pacemaker/defibrillator, and obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP) device use. The FAA issued the pilot an Authorization for Special Issuance for a Second-Class medical certificate with permanent pacemaker implantation, atrial fibrillation, obstructive sleep apnea treated with CPAP and the use of medication.

The pilot’s cardiovascular disease was associated with an increased risk of sudden impairment or incapacitating cardiovascular event such as ventricular arrhythmia, heart attack, or stroke. No forensic evidence indicated that such an event occurred. However, such events do not leave reliable autopsy evidence if the event occurs just before death, and no data were available from the pilot’s implanted pacemaker/defibrillator. Thus, the investigation was unable to determine if sudden incapacitation or impairment was a factor in this accident.

Postaccident examination found no evidence of preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. Flight control continuity from the cockpit controls to the primary flight control surfaces was established; the observed flight control cable separations were consistent with damage sustained during the accident sequence.

The airplane flight manual specified that the flaps should be in the Up position for takeoff. However, witnesses observed the airplane taxi and takeoff with the flaps fully extended. One witness reported that the airplane appeared to be moving extremely slowly after liftoff and that, although the landing gear retracted, the flaps remained fully extended. At an altitude of about 200 to 300 ft agl, the airplane pitched up, and the witness observed the left wing drop before the airplane entered a nose-down descent. The video study showed that the airplane flew approximately straight until about 4.7 seconds before impact, when it began a left turn, and that it impacted terrain in an approximately 90° left-wing-down attitude. The observed pitch increase, left-wing drop, and subsequent nose-low descent were consistent with the airplane exceeding its critical angle of attack and entering an aerodynamic stall at an altitude insufficient for recovery.

Verbatim NTSB analysis and probable cause from the NTSB dataset