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A320, Oslo Norway, 2010
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Revision as of 10:04, 17 October 2011 by Integrator1
On 25 February 2010, an Airbus A320-200 being operated by Aeroflot on a scheduled passenger flight from Oslo to Moscow Sheremetyevo successfully took off in normal daylight visibility from an unobstructed taxiway parallel to the designated departure runway 01L. The flight was a line training sector for the First Officer and a Safety Pilot was occupying the flight deck Observer. The flight crew reported that they had not appreciated that they had taken off from the taxiway until informed of this by ATC after take-off.
An Investigation was carried out by AIBN. The diagram below shows the position from which the incident aircraft taxied ( a solid red triangle) via taxiways ‘G’ and ‘N’ for departure from Runway 01L at A3 and the orange line indicates where the aircraft took off northbound on taxiway M after receiving take off clearance for Runway 01L whilst taxiing.
It was found that the aircraft commander was a Training Captain and had acted as PF for the departure. He was acting as the supervising instructor for the First Officer who was undergoing line training on the aircraft type. During the taxi out, it was found that only the PF, who had the Jeppesen aerodrome plate in his view, was directing his main focus out of the window. There was no monitoring of the actions of the PF whilst taxiing as neither of other two pilots “(paid) much attention to what was outside the cockpit windows”. The First Officer was ‘head down’ and the Safety Pilot was observing how the First Officer handled his tasks in accordance with his responsibilities. The 23 metre width of the taxiway, compared with the runway width of 45 metres, did not alert the PF to the taxiway line up.
It was established that the taxiway used for take off, taxiway ‘M’, had an available length of 1652 metres from the point where the take off roll was commenced compared to 2696 metres from the equivalent point on the parallel runway which should have been used. Under the prevailing conditions, taxiway M was, by chance, long enough for the aircraft to take off with an actual take off roll of 1245 metres subsequently calculated before the main wheels lifted off the ground leaving another 407 metres before the end of the taxiway. There were also, fortuitously, no other traffic or obstacles of any other description on taxiway ‘M’ at the time.
In respect of the pavement surfaces and surface markings, it was noted that runway 01L was of concrete with asphalt ‘shoulders’ beyond the runway edge markings which added a further 15 metres to the paved width. Taxiway ‘M’ was of asphalt and had shoulders of the same material beyond the taxiway edge markings which added a further 22 metres to the paved width.
Of significance to the event was the fact that Norway had a surface markings policy contrary to ICAO SARPs in that markings on both taxiways and runways are yellow. Although the Norwegian CAA had reviewed this exceptional policy after an AIBN Safety Recommendation to that effect following a similar previous event at Oslo, it had decided that it was not necessary to change it.
In respect of the ATC circumstances, it was noted that the event took place during a quiet time of the day with little traffic and that the use of intersection take offs at the airport was common if conditions were suitable. On a point of detail, it was noted that “the phraseology used for one taxi instruction was not in line with the ICAO standards” but that radio communications between the aircraft and ATC were otherwise normal. The issue of an early unrestricted take off clearance when quiet was confirmed as normal and permitted practice.