Wreckage of Flight 2904 on 15 September 1993 |
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| Accident summary | |
|---|---|
| Type | Overshot runway, Pilot Error |
| Site | Warsaw, Poland |
| Passengers | 64 |
| Crew | 6 |
| Injuries | 68 |
| Fatalities | 2 |
| Survivors | 68 |
| Aircraft type | Airbus A320-211 |
| Operator | Lufthansa |
| Tail number | D-AIPN |
Lufthansa Flight 2904 was an Airbus A320-200 which overran the runway, in Okęcie International Airport on 14 September 1993. It was a flight from Frankfurt, Germany to Warsaw, Poland.
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Lufthansa Flight 2904 was cleared to land at Okęcie International Airport Rwy 11 and was informed of the existence of wind shear on the approach.[1] To compensate for the crosswind, the pilots attempted to touch down with the aircraft banked slightly to the right. Additionally they landed with a speed about 20 knots (37 km/h) faster than usual. According to the manual, this was the correct procedure for the reported weather conditions. But the weather report was not up to date. At the moment of touch down, the assumed crosswind turned out to be a tailwind. Due to the tailwind of approximately 20 knots (37 km/h) and the increased speed the airplane hit the ground at approximately 170 knots (310 km/h) and far beyond the normal touch down point. The aircraft's right gear touched down 770 m from the runway 11 threshold. The left gear touched down 9 seconds later, 1525 m from the threshold. Only when the left gear touched the runway did the ground spoilers and engine thrust reversers deploy, these automatic systems depending on oleo strut (shock absorber) compression. The wheel brakes, triggered by wheel rotation being equal to or greater than 72 knots (133 km/h) began to operate after about 4 seconds. Seeing the approaching end of the runway and the obstacle behind it, the pilot steered the aircraft off the runway to the right. The aircraft departed the runway at a speed of 72 knots (133 km/h) and rolled 90 m before it hit the embankment and an LLZ aerial with the left wing. A fire started in the left wing area and penetrated into the passenger cabin. Two of 70 occupants died in this accident, including the co-pilot who died on impact and one passenger who was unable to escape because he lost consciousness as a result of the smoke in the cabin.
Marcin Bronikowski, a passenger, told Warsaw Radio ZET station that the incident occurred "in a fraction of a second after landing" and that "there was even hand-clapping after the landing."[1]
The cause of the accident was incorrect decisions and actions of the flight crew. Some of the incorrect decisions were taken when information about windshear was received by the crew. The windshear was produced by the front passing over the airport; accompanied by intensive variation of wind parameters as well as by heavy rain on the runway itself.
To ensure that the thrust-reverse system and the spoilers are only activated in a landing situation, the software has to be sure the airplane is on the ground even if the systems are selected mid-air. The spoilers are only activated if either of these conditions are true:
The thrust reversers are only activated if the latter condition is true. There is no way for the pilot to override the software decision and activate either system manually.
In the case of the Warsaw accident neither of the first two conditions was fulfilled, so the most effective braking system was not activated. Point one was not fulfilled, because the plane landed inclined (to counteract the anticipated crosswind). Thus the pressure of 12 tons on both landing gears required to trigger the sensor was not reached. Point two was also not fulfilled because of a hydroplaning effect on the wet runway.
Only when the left landing gear touched the runway did the automatic aircraft systems allow the ground spoilers and engine thrust reversers to operate. Due to the braking distances in the heavy rain the aircraft could not stop before the end of the runway. The computer did not actually know the aircraft had landed until it was already 125 meters beyond the half way point of runway 11.
Lufthansa stopped using the number 2904 for this flight and re-numbered to 3302, whilst others on the same route were re-numbered to 3300 and 3304, respectively. In November 2010, the Frankfurt-Warsaw route received the flight numbers 1346, 1348 and 1350 as part of a general re-numbering of the entire European network. As of October 27, 2011, the number 2904 is again used (Berlin to Nurnberg flight).
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