What happened
On March 20, 2016, at approximately 21:45 UTC, a Raytheon C90A, registration PT-PAC, was performing a repositioning flight from São Carlos (SDSC) to Sorocaba (SDCO) in Brazil. The flight, which included a pilot and two passengers, was diverted back to the origin airport after the pilot learned that the scheduled maintenance services at the destination were unavailable.
The landing was conducted at night, despite the São Carlos aerodrome being authorized for daytime VFR operations only. The pilot executed an approach with a high glide slope and a speed of 110 KIAS, which was 9 knots above the manual's recommended speed. Due to this excess energy, the aircraft touched down approximately 470 meters from the runway threshold, well beyond the intended touchdown zone.
Upon touchdown, the pilot applied maximum braking and reverse thrust. This rapid transition caused a power asymmetry, as the left engine did not respond with the same efficiency as the right. This imbalance caused the aircraft to veer toward the right side of the runway. The aircraft exited the runway pavement, traveled 60 meters across adjacent grass, and struck an embankment, resulting in substantial damage to the landing gear and engines. All three occupants escaped without injury.
The investigation
CENIPA's investigation focused on the flight parameters and the legality of the operation. Investigators established that the pilot held valid medical and multi-engine ratings and that the aircraft was airworthy and within weight and balance limits. However, maintenance logs for the airframe, engines, and propellers were not provided for review.
The investigation examined the approach dynamics, noting that the high approach speed and steep descent slope prevented a stabilized approach. The investigators also analyzed the aerodynamic effects of the reverse thrust application, noting that the aircraft's speed was near the limit where the reverse system might not engage uniformly, contributing to the loss of directional control.
Findings
- The pilot conducted a night approach at an aerodrome not authorized for night VFR operations.
- The approach was unstabilized, characterized by a high glide slope and excessive airspeed.
- Power asymmetry occurred during the application of reverse thrust, leading to the loss of directional control.
- Inadequate flight planning regarding the aerodrome's operational hours and night-time visual references.
- Improper command inputs during the critical phase of landing to compensate for the long landing distance.