What happened
On March 23, 1996, a CAP 4 aircraft, registration PP-RQL, operated by Aeroclube de Limeira, crashed during a local flight at the Limeira Aerodrome in São Paulo. The flight was initiated following a social event at the flying club.
During the takeoff roll, witnesses observed that the aircraft covered a shorter distance on the ground than usual. Upon rotation, the aircraft reached an altitude of approximately 30 meters before entering an abnormal attitude. The aircraft entered a left-hand turn and a nose-down attitude, rotating approximately 180 degrees relative to the takeoff axis. The aircraft subsequently struck the ground and exploded, triggering a rapid fire that consumed the wreckage. The impact and subsequent fire resulted in two fatalities among the crew.
The investigation
CENIPA's investigation focused on the sequence of events during the takeoff and the operational environment. Investigators examined the aircraft's maintenance history, noting that the CAP 4 had undergone its 100-hour inspection and 1,000-hour overhaul only eight hours prior to the accident.
The investigation evaluated two primary hypotheses regarding the loss of control. The first suggested the pilot in the rear seat may have rotated the aircraft at a lower speed to avoid pedestrians crossing the runway. The second, and more probable, hypothesis established that the pilot in the front seat rotated the aircraft before reaching the required speed and applied an excessive pitch attitude. This led to an aerodynamic stall that was not corrected by the crew.
Additionally, the investigation looked into the human factors, noting that the pilots were in a state of relaxation following a club barbecue, which contributed to a lack of proper flight planning and briefing. The investigation also noted that the instructor was occupying the rear seat, despite the flight not being a training mission, and that the aerodrome's perimeter fence was frequently breached by local residents.
Findings
- Improper flight planning: The crew failed to conduct an adequate briefing or flight planning prior to departure.
- Pilot error: The pilot in the front seat applied an excessive pitch attitude during takeoff, leading to a loss of control due to an aerodynamic stall.
- Human factors: The psychological state of the pilots, characterized by relaxation and distraction following a social event, influenced their performance.
- Operational deficiency: There was a lack of established procedures regarding which seat an instructor should occupy during non-training flights.
- Inadequate supervision: The aeroclube's operations department failed to regulate seat occupancy for instructors during general flights.
- External interference: The damaged perimeter fence allowed unauthorized persons to access the runway, potentially impacting the takeoff sequence.