AMSTELVEEN A KLM Boeing 737-800 with 184 passengers and 7 crew members on board took off from Buitenveldertbaan on 10 June 2018 with incorrect data. This emerges from studies conducted by the Dutch Security Council. A vacant runway length of 3,494 meters was assumed, while this was in fact only 2,460 meters from the designated ramp due to a last minute change. According to the Dutch Security Council, it is more common for such errors to be committed under time pressure. The Council therefore only recommends calculating and entering changed take-off data when the aircraft in question is stationary.
The KLM aircraft was ready for a flight from Schiphol to Munich Airport in Germany on 10 June 2018. The aircraft would take off from Buitenveldertbaan. As the aircraft approached this runway, the air traffic controller asked if it was possible to take off from ramp N4 on this runway. The crew responded in the negative. Due to the prevailing wind and because the take-off weight was close to the maximum take-off weight, the aircraft could only take off from the start of the runway, via ramp N5. The take-off data for a take-off from this position was entered into the Flight Management Computer (FMC).
LIMITATION OF DELAY During the taxi to the starting point, however, it turned out that the wind conditions had changed, which made it possible to take off from ramp N4. By using this ramp, the crew was able to limit delays as the aircraft was already behind schedule. After the air traffic control had ordered the aircraft to taxi to ramp N4, new take-off data had to be calculated with the current wind conditions for a take-off from this location. This happened just before the plane entered the runway of one of the crew members.
NOT CHECKED The investigation revealed that only the new wind data had been entered in FMC, where the ramp N5 was not changed to N4. The newly calculated and entered start data were also not checked by the other crew members. As a result, the calculation of the starting parameters was based on an available track length of 3,494 meters instead of the actual 2460 meters. After the takeoff, the plane came off the runway 176 meters before the end.
INSUFFICIENT POWER Although the crew suspected that something was wrong under the starter roller, no power was supplied. The available track length was actually 1,034 meters shorter than the track length used by the automatic engine power system to calculate the required engine power. As a result, the available force was insufficient for a safe start.
DANGEROUS SITUATIONS The Dutch Security Council points out that planes that take off with incorrectly entered take-off data create dangerous situations that can even lead to loss of life. According to the Council, several incidents in the aviation sector show that this incident is not an isolated incident. ‘Accidents and serious start-up events due to the use of incorrect start-up data occur with a certain regularity. Last-minute changes, time constraints, urgency and failure to implement individual controls are the factors that most often contribute to the launch of performance events. “
STOPPER Despite ongoing developments, according to the Dutch Security Council, there are currently no technical solutions available to completely prevent starting with incorrect data. ‘Therefore, the prevention of this must be sought in operating solutions for the time being. To give the crew more time to check and enter the changed data, it is recommended to stop the aircraft before performing these operations. This moment should be considered as one of the most important practices to prevent incorrect entry of startup data, “said the Research Council