Incident Overview
On 10 February 1999, an Israel Aircraft Industries ASTRA aircraft, operating a commercial passenger flight from Granada, Spain, to Braunschweig, Germany, experienced a serious incident during landing. After landing on runway 26, while turning onto taxiway CHARLIE, the aircraft departed the runway surface and came to rest on soft ground after a short roll. The event occurred at 1822 local time (1722 UTC). No injuries were reported among the two pilots and seven passengers, and the aircraft sustained no visible damage. A runway edge light was destroyed during the excursion.
Flight Crew Account
According to the flight crew, the visual approach was conducted using PAPI (Precision Approach Path Indicator) guidance. The runway condition was assessed as dry during the approach. The crew performed a positive touchdown in the touchdown zone to achieve early braking effectiveness. Reverse thrust was used until approximately 80 knots. The braking action provided by the wheel brakes thereafter was unexpectedly low, resulting in excessive speed at the end of the runway. The aircraft then slid sideways from the taxiway and stopped on soft ground. The second pilot reported the excursion to Braunschweig Tower via radio.
Air Traffic Observations
Tower controllers observed the landing and noted that the aircraft appeared to approach faster than usual and touched down later than typical from their perspective. Due to darkness and their position, they did not see the excursion and learned of it through the radio report. They subsequently notified an air traffic supervision employee, who drove to the scene via runway 26. The employee used a Tapleymeter—a device that measures deceleration during braking—to evaluate runway braking action. Multiple brake applications during the drive indicated a braking action of "good."
Runway Condition Investigation
Weather and runway condition reports were inconsistent, prompting further investigation. Approximately 20 minutes before the incident, light snow began falling from the west, progressively degrading the runway condition. Two pilots who landed earlier reported minor difficulties during taxiway turnoffs. The pilot who landed five minutes before the incident reported "braking action medium to good" and described the end of the runway as "slippery." The incident pilot described braking action as "poor." Photographs taken by police two hours after the event showed snow covering the taxiway CHARLIE area, and a mark from a brief wingtip contact with the ground was visible.
Radar and Performance Analysis
Radar data from the approach showed a constant ground speed of approximately 125 knots during the final approach, which matched the calculated Vref from the flight manual. Touchdown was estimated at 300 to 350 meters behind the threshold, which is 500 meters from the runway start due to a 180-meter displaced threshold. Landing distance calculations based on actual conditions (weight: 19,000 lbs, flaps: 40°, wind: 200°/4 kt, temperature: -2°C, QNH: 1006 hPa) yielded a wet landing field length of 1,378 meters, slightly less than the available landing distance of 1,380 meters. The displaced threshold and PAPI positioning were noted but not directly linked to the incident.