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AT43, vicinity Glasgow, UK 2012

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Revision as of 10:22, 15 October 2013 by Integrator1 (talk | contribs)

Description

On 22 February 2012, an ATR 42-300 being operated by Irish operator Air Contractors on a night scheduled cargo flight from Newcastle to Glasgow for Fed Ex and flying level on the Instrument Landing System (ILS) LOC in Instrument Meteorological Conditions (IMC) to intercept the ILS GS lost airspeed and the stall warning was activated. The recovery was commenced normally but speed in manual flight was then first allowed to increase above the deployed flap limit speed and then to reduce to the extent that a second stall warning was almost triggered before a stabilised approach was regained as the aircraft approached 3nm from touchdown.

Investigation

An Investigation by the UK AAIB was commenced once the circumstances became apparent, but the process of serious incident notification was delayed. Both the 2 hour Cockpit Voice Recorder (CVR) and the Flight Data Recorder (FDR) record were available to assist the Investigation but access to some of the FDR information was delayed because of errors made by the contractor engaged by the operator to carry out periodic and mandatory EU-OPS requirements aimed at validating FDR output to fully follow the correct process. However, all the required data was eventually found to have been preserved and retained.

It was established that the incident flight was the final one of a sequence of three, the first two of which had involved operating from Manchester to Paris CDG to Newcastle. The aircraft commander had acted as PF for the first sector and then again for the incident flight. The CVR record showed that during the Newcastle-Glasgow sector, he had initiated conversation on a range of non operational topics both above and below FL100, the latter being contrary to the operator’s sterile flight deck policy which required that when below FL100, only operational matters were to be the subject of conversation. It was observed that the Co-Pilot’s responses had been “polite but brief” and also that both pilots had missed or mis-heard ATC communications during the flight and some SOPs besides the sterile flight deck policy had not been adhered to.

En route, icing conditions ahead required the selection of anti icing equipment on but upon receipt of the destination weather, the Co-Pilot noted that it would be possible to perform the approach using the non-icing reference speed which was 15 knots lower than the corresponding icing reference speed. However, it was noted from the CVR that in the subsequent briefing by the commander had not clarified which speeds were to be used and had also ignored other topics stipulated in Company procedures. The flight received radar vectors to the ILS 23 with the AP engaged and crew awareness of high ground in the vicinity of the approach track and vertical profile. Just inside 10nm and at 3000 feet QNH and 215KIAS, power was reduced to about 15% and when a further descent to 2000 feet was given together with clearance to establish on the ILS LOC and GS in that order, VS mode was engaged. When the AP levelled the aircraft at 2000 feet QNH with the LOC captured and the GS just above, power was reduced to 3% and, unnoticed by either pilot, the airspeed steadily decreased as the AP attempted to maintain 2000 feet. The stick shaker then activated with the aircraft at approximately 1700 feet agl, at 111 KIAS and with an angle of attack of +11.2°. The AP disconnected and the PM remarked sharply in response to which the PF pitched down and increased power. However, the transition from stall warning recovery to the ILS approach was mishandled and the aircraft then went above the GS and the maximum speed for the deployed flap 15 (170 KIAS) was exceeded. During the response to this, the aircraft speed reduced to 111 KIAS and the angle of attack almost reached the point which would have triggered a second stall warning. Eventually, at a range of 3.4nm from the runway, with the aircraft stabilised and fully configured for landing, the AP was re-engaged and the rest of the approach and landing were completed without further event until touchdown when a nacelle overheat warning activated. The crew did not action the associated procedure.