What happened
On September 10, 2018, a Mitsubishi MU-2B-60, registration PT-LJS, was performing a private flight from Aeródromo Estância Machado to Araçatuba Aerodrome (SBAU) in São Paulo, Brazil. The flight was part of a multi-leg leisure trip involving a pilot and one passenger.
During the approach to runway 05, the pilot failed to extend the landing gear. The aircraft touched down on its fuselage, traveling approximately 638 meters along the centerline before coming to a complete stop. While the two occupants escaped without injury, the aircraft sustained substantial damage, specifically to the landing gear and their respective housings.
The investigation
CENIPA investigators examined the pilot's operational history and the aircraft's technical systems. The pilot was highly experienced, with approximately 7,000 total flight hours and over 300 hours in this specific model. The investigation focused on why the landing gear remained retracted despite the pilot performing a checklist.
Investigators noted that the pilot utilized a "do and read" checklist technique, where actions are performed from memory before being verified against the written list. It was discovered that the pilot had previously flown lower-performance multi-engine aircraft where the gear extension sequence occurred before flap deployment. In the Mitsubishi MU-2B-60, the checklist requires 5° of flaps during the approach phase, with gear extension occurring later in the "before landing" phase. This inverted sequence likely led to a cognitive error.
Furthermore, the aircraft was equipped with an aural warning system designed to alert the crew if the gear was retracted while power levers were near flight idle. While the system was found to be fully operational during post-accident testing, investigators believe the warning may not have triggered because the pilot's approach profile required higher power settings, preventing the throttles from reaching the threshold required to activate the horn.
Findings
- The pilot failed to extend the landing gear prior to touchdown.
- The pilot's checklist verification failed to identify the retracted gear status.
- Negative transfer of learning from previous, lower-performance aircraft models influenced the pilot's procedural memory regarding the sequence of flaps and gear extension.
- The pilot's use of the "do and read" technique contributed to the oversight.
- The aural landing gear warning did not activate, likely due to the power lever position during the approach.