What happened
On June 29, 2003, a Saab 2000, registration HB-IYB, operated by Swiss International Airlines, was performing a scheduled flight from Lugano to Olbia. The flight, carrying 24 passengers and 4 crew members, was cleared for a visual approach to runway 24. During the final stages of the approach, the aircraft was flying at a significantly high speed—more than 20 knots above the target Vref—and in a steep descent.
Despite multiple warnings from the Ground Proximity Warning System (GPWS), including "sink rate" and "too low terrain" alerts, the crew did not execute a missed approach. The aircraft touched down primarily on the nose gear. Because the main gear had not yet made sufficient contact with the runway, the Weight On Wheel (WOW) system failed to activate, which in turn prevented the anti-skid system from engaging. Additionally, the crew failed to use the BETA OVERRIDE to manually activate the thrust reversers. Consequently, the main wheels locked up upon braking, and the aircraft slid along the runway, eventually exiting the paved surface and causing significant damage to the landing gear wheels and tires.
The investigation
The investigation, conducted by the Italian ANSV, examined the flight data recorder, the aircraft wreckage, and the crew's performance. Investigators found that the main landing gear rims were severely damaged and deformed, with heavy rubber deposits and metal fragments left on the runway. Technical analysis confirmed that all onboard systems, including the anti-skid and touchdown protection, were functioning according to design specifications. The investigation also reviewed the flight crew's training records and the airline's operational procedures regarding visual approaches and stabilized approaches.
Findings
- The primary cause was an unstable approach characterized by excessive speed and a high descent rate.
- The nose-first touchdown prevented the activation of the Weight On Wheel (WOW) signal, rendering the anti-skid system unavailable.
- The crew failed to initiate a missed approach despite the captain noting the excessive altitude and speed on four separate occasions.
- There was a significant lack of Crew Resource Management (CRM), evidenced by degraded situational awareness and a failure in leadership and decision-making by the captain.
- The crew did not perform the required read-backs for ATC landing clearances.
- The failure to engage the thrust reversers via the BETA OVERRIDE contributed to the inability to decelerate the aircraft.
Safety action
- A recommendation was made to aviation authorities (ENAC and UFAC) to ensure airlines carefully evaluate the psycho-attitudinal assessments of pilots promoted to command positions, particularly regarding their ability to handle stress and coordinate with crew members.
- A recommendation was issued to emphasize the absolute necessity of adhering to stabilized approach procedures during periodic flight crew training.