Deficient cockpit procedures and insufficient pilot alertness were the main causes for an Aeroflot Airbus A320 flight crew becoming disoriented and taking off from a taxiway at Oslo's Gardermoen airport earlier this year.

However, the Accident Investigation Board Norway (AIBN) also determined that insufficient monitoring from the control tower and inadequate signposting in the manoeuvering area contributed to the serious incident on 25 February 2010. The pilots of AFL212 had requested a departure from the intersection A3 on runway 01L and were taxiing south along the parallel taxiway N. Taxiway M, from where the aircraft eventually took off, runs parallel in-between runway 01L and taxiway N.

As there were no other aircraft or vehicle traffic in the airport's western runway system at the time, air traffic control (ATC) issued the takeoff clearance well in advance while the passenger jet was still on taxiway N. The pilots later turned right onto the intersection but, instead of taxiing ahead towards the A3 holding point at runway 01L, continued turning right for a 180-degree turn onto taxiway M, from where they took off.

Accustomed to being instructed by Russian ATC to line up and wait on the departure runway, the captain assumed the takeoff clearance had been given on the taxiway closest to runway 01L and thus mistook taxiway M for the runway.

Aeroflot had no procedure for the flight crew to actively confirm that they were on the correct runway before departure at the time. This was aggravated by the co-pilot focusing on outstanding pre-takeoff checks and not looking to the outside of the aircraft. However, the mistake was not even picked up by a check captain who was also on the flight deck. The Accident Investigation Board Norway has recommended that Aeroflot establish a runway verification practice into its standard operating procedures (SOP). It also urged airlines to complete as many pre-takeoff check points as possible before taxiing begins to keep later checklists short and allow for the crew to focus on the aircraft's movement.

While it was not required for ATC to wait with the takeoff clearance until the aircraft had passed a point where the only remaining possibility for take-off was on the relevant runway, the aircraft's movement should have been monitored more carefully, the investigators say. This was especially the case as there had previously been several taxiing mistakes in the N-M-A3 area. The airport had even identified the location as a warning 'hot spot' and initiated changes in the airport map, but these had not been realised by the time of this serious incident.

The investigation board had also made a safety recommendation in 2006 to implement a respective ATC rule when a takeoff clearance should be issued. The Norwegian Civil Aviation Authority did not take this advice further at the time but has opened it in the meantime.

No attempts had been made to improve the taxi- and runway signs in the area before the incident. The signs along taxiway N pointing towards the A3 holding point had no reference to taxiway M lying in-between. There was also no identification sign on taxiway M in the intersection vicinity. The missing signs contributed to the captain's mistake, according to the investigators, and have been rectified after the incident.

The Aeroflot pilots did not realise their taxiing mistake until they were notified by ATC after departure. The aircraft continued to Moscow where it landed without further incident. The Accident Investigation Board Norway emphasised that, under the prevailing conditions, taxiway M was "by chance" long enough for the aircraft to take off - and fortunately also free of other traffic and obstacles at the time of the incident.

Source: Air Transport Intelligence news