What happened
On the early morning of January 16, 1999, a Cessna 501 Citation, registration CS-AYY, was operating a non-scheduled passenger flight from Faro to Cascais Municipal Aerodrome. The aircraft was carrying eight occupants, including two crew members and six passengers.
After receiving approval from Lisbon Approach for the approach and descent to runway 35, the co-pilot began the landing maneuvers. During the approach, the pilot commander noticed the aircraft was flying below the established glide slope and instructed the co-pilot to make immediate corrections. When the aircraft continued to sink despite these efforts, the pilot commander took control of the aircraft, applying nose-up trim and increasing engine power. However, the maneuver failed to stabilize the descent profile, and the rear underside of the fuselage struck the runway pavement.
The investigation
The GPIAAF investigation examined the flight history, aircraft maintenance, and crew performance. Investigators noted that the aircraft was landing at a weight near its maximum landing mass. The investigation also reviewed the operator's training methodology, noting that Helisul conducted proficiency checks during real flights rather than in a flight simulator, primarily due to the high cost of simulator training for executive jets.
Findings
- The pilot commander failed to adhere to the approved Flight Manual procedures during the landing phase.
- The crew utilized a reference speed (Vref) of 107 knots, which the manual recommends only for use at the runway threshold, rather than during the approach.
- The attempt to correct the sinking aircraft by increasing nose-up attitude and power was counterproductive, as the delay in engine thrust response can lead to further descent.
- The primary cause of the incident was improper aircraft operation during the approach and landing phase by the crew.
- The impact resulted in structural deformation of the fuselage tail cone and the lower part of the vertical stabilizer.
- There were no injuries to the eight occupants on board.