What happened
On 24 October 2010, a Schleicher - ASK 21 glider, registration EI-GLB, was conducting a dual instructional flight at Gowran Grange Airfield (EIGN) in Co. Kildare. The flight, which involved an instructor and a student, had been performing a familiarization session following a six-month hiatus for the student. After being towed to 3,000 feet, the aircraft returned to the airfield to land on the opposite end of the grass runway.
During the final approach, the aircraft was positioned too high. While the student had attempted to lose altitude using airbrakes, the instructor eventually took control to manage the descent. To increase the rate of descent, the instructor fully extended the airbrakes and initiated a side-slip. However, the maneuver was not completed at a sufficient altitude. The glider struck the ground with significant force, bounced, and subsequently impacted the ground in a nose-down attitude. The aircraft slid across the field, rotating 180 degrees before coming to rest, resulting in substantial aircraft damage.
The investigation
The AAIU examined the aircraft and the site of the accident. The investigation found that the glider's tail section had been severed behind the wings, the horizontal stabilizer had detached, and the nose area was crushed. A technical inspection of EI-GLB confirmed that the flight controls were functional and no pre-existing mechanical defects contributed to the event.
Investigators also reviewed the flight path. The approach was a straight-in maneuver rather than a standard circuit pattern. The investigation noted that during a side-slip in this specific aircraft type, airspeed indications are not reliable, making it difficult for the pilot to verify the correct approach speed upon exiting the maneuver.
Findings
- The decision to skip a standard circuit pattern was inconsistent with established airmanship.
- The aircraft was too high on the final approach, necessitating a corrective maneuver.
- The recovery from the side-slip was initiated at too low an altitude, preventing the crew from stabilizing the aircraft and re-establishing the proper landing speed.
- Inadequate control of the flight path during the approach contributed to the unstable landing.