What happened
During a flight originating from Istanbul and destined for Southampton, the aircraft performed a procedural ILS approach and touched down on runway 20. During the final approach phase, the crew encountered wind shear, which resulted in a 10-knot reduction in airspeed, prompting an increase in engine power to maintain stability. The aircraft made contact with the runway approximately 500 feet from the threshold.
Following touchdown, the crew found that applying maximum braking force did not effectively decelerate the aircraft. Suspecting the presence of aquaplaning, the crew attempted to utilize reverse thrust; however, they did not receive a cockpit indication confirming that the thrust reversers had deployed correctly, leading them to believe the system was non-functional. The aircraft continued to travel down the runway, with the crew attempting to steer the plane along the remaining 1,500 feet of pavement. Ultimately, the aircraft exited the runway and came to a stop 75 meters into the adjacent grass area. The excursion caused the engines to ingest earth and stones, and the right wing fuel tank sustained a puncture.
Findings
An inspection of the runway surface conducted 10 minutes prior to the incident noted that while the runway was wet, there was no evidence of standing water. Friction testing performed at 1646 hrs recorded Mu values of 0.67, 0.66, and 0.57 across the first, second, and third runway segments, respectively. The primary factor in the excursion was the ineffective braking and unconfirmed deployment of reverse thrust following the encounter with wind shear.