What happened
On the evening of 29 June 2022, a Piper PA-34-220T Seneca III, registration ZS-MBY, was conducting a type conversion training flight at Grand Central Aerodrome in Gauteng. The flight, operated under Part 1ically 141 regulations, involved a flight instructor and a student pilot. The weather was clear, and the flight was conducted under visual meteorological conditions at night.
After successfully completing three circuits and touch-and-go landings, the crew began the fourth circuit. While on the final approach to Runway 17, the student pilot believed the landing gear had been deployed, having verbally called out "gear down" during the downwind and base legs. However, as the aircraft crossed the runway threshold at approximately 50 to 100 feet, the aircraft did not settle on its wheels. Instead, a loud grinding noise and sparks were observed as the underbelly of the aircraft made contact with the runway. The aircraft slid approximately 90 metres before coming to a halt. There were no fatalities and no injuries to the occupants, though the aircraft sustained substantial damage to the engines, propellers, flaps, and fuselage underbelly.
The investigation
SACAA AIID investigators examined the aircraft and the flight crew's actions. Post-accident inspections by an aircraft maintenance engineer revealed that the landing gear system and the warning horn were fully functional. When tested on hydraulic jacks, the gear cycled normally and the warning horn activated correctly. Notably, the lack of scrape marks on the landing gear doors suggested the gear was actually retracted during the impact.
Regarding the crew, the investigation found that while the instructor held a valid license, the student pilot's private pilot license had expired at the time of the accident. The investigation also looked into why the landing gear warning horn did not alert the crew. It was noted that the horn is designed to trigger only when the throttle is at a low setting (12-15 inches of manifold pressure); if the power setting remained above this threshold, the warning would not sound.
Findings
- The primary cause of the accident was that the landing gear selector was not moved to the down position on final approach.
- The crew relied on verbal confirmations rather than physically verifying the gear position on the instrument panel.
- A lack of monitoring and the presence of confirmation bias—where the success of previous circuits led the crew to assume the gear was down—prevented the detection of the error.
- The landing gear warning system likely failed to alert the crew because the engine manifold pressure may have remained above the 15-inch threshold required to trigger the horn.
Safety action
Following the incident, the aircraft operator implemented several safety improvements, including revising the pre-landing checklist for instructors training on complex aircraft. New procedures require checking failsafe systems during descent and when joining the circuit. Additionally, instructor proficiency checks will now include more rigorous training on the aircraft's built-in safety systems.