What happened
On February 26, 1999, a Gulfstream Commander 690C, registration N24A, departed from a private airfield in Bolgheri, Italy, bound for Bern via Pisa. The flight was a private VFR operation carrying a pilot and two passengers. During the takeoff roll, a deer crossed the runway from the right, resulting in a violent collision with the right main landing gear.
Because the remaining runway length was insufficient to abort the takeoff, the pilot continued the climb. Upon observing through the cockpit window that the right wheel had rotated 90 degrees due to the impact, the pilot attempted to retract the landing gear. While the nose gear and left main gear retracted and locked normally, the right gear only partially retracted. After an intermediate stop in Pisa, the pilot coordinated with authorities and decided to divert to Zurich, as the local maintenance facility for the aircraft was located in Bern, but Bern lacked the necessary equipment to handle the emergency.
At Zurich Airport, emergency services deployed a foam carpet approximately 900 meters long and 17 meters wide on runway 14. The pilot executed the landing with the gear retracted. The aircraft touched down smoothly on the foam but continued past the end of the carpet, coming to a stop approximately 50 meters beyond the foam, slightly offset to the right.
The investigation
SUST examined the aircraft and the circumstances of the collision. The investigation confirmed that the pilot held a valid US commercial license and possessed sufficient flight experience and recent training on the aircraft type. The aircraft's maintenance records showed it was properly maintained, with the last 100-hour inspection completed earlier that year.
Upon inspection of the landing gear, investigators found that the right main wheel had indeed rotated 90 degrees, and the upper scissor—the component responsible for maintaining the parallel alignment of the wheel—had broken. The impact with the deer was the direct cause of this structural failure. Subsequent tests on the aircraft while on jacks showed that the landing gear could function normally when the gear was manually extended and locked.
Findings
- The primary cause of the emergency landing was the damage to the right main landing gear caused by a collision with a deer during takeoff.
- The pilot's decision to continue the takeoff after the strike was deemed appropriate, as an immediate abort would have been impossible given the remaining runway length.
- The landing gear failure was specifically due to the breakage of the upper scissor mechanism.
- The use of the foam carpet at Zurich Airport was sufficient and properly implemented, though the aircraft's touchdown point was offset, causing it to overshoot the foam.