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Ground power unit. (Source: Aviation police).
Ground power unit. (Source: Aviation police).

Fokker 70 lost all braking pressure during taxi-in, 5 March 2015

Status : Closed

After landing at Amsterdam Schiphol Airport on 5 March 2015, the Fokker 70 registered as PH-WXC, left runway 18R and taxied in without any anomalies. When arriving at the assigned free stand parking position the crew applied the brakes, without any braking action response. The aircraft hit a ground power unit (GPU) which got damaged. Ground handling staff had to run to avoid being hit or run over. Eventually, the aircraft came to a stop on a main taxiway.

The loss of braking capacity posed a serious risk to the ground handling staff in the first place. Additionally, there was a risk of colliding with more objects, in particular with other taxiing aircraft on the main taxiway. Attentiveness of the ground handlers, actions of the flight crew and the fortunate circumstance that there was no nearby traffic ultimately limited the consequences of the event.

Ground-flight detection failure resulting in collision

The aircraft brake system is supported by the anti-skid system to keep control over the aircraft and optimise braking capacity during landing. The operation of the anti-skid system is - amongst others - controlled by input from the ground-flight control system. All aircraft systems related to braking functioned correctly, except a part of the groundflight control system. The majority of the output channels of the ground-flight control system as input to other aircraft systems remained in ground mode as required. However, QAR data and aircraft system analysis confirmed that both the left and right main landing gear (MLG) output channels had switched from ground mode signal into flight mode signal. This failure resulted in a response of the anti-skid system which commanded – as designed - to dump the pressure in all brake units which normally provide touchdown (locked wheels) protection during landing.

Besides the full report, a Dutch summary is also available.

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