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SW4, Cork Ireland, 2011

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Revision as of 11:03, 29 January 2014 by Integrator1 (talk | contribs)

Description

On 10 February 2011, a Fairchild SA 227-BC Metro III being operated by Spanish Company Flightline exclusively for an Isle of Man based “Ticket Seller” called Manx2 (which was not also an aircraft operator) on a scheduled passenger flight from Belfast City, UK to Cork, Ireland crashed when the crew lost control whilst attempting to commence a daylight go around at destination after failing, on the third attempt, to transition to visual reference for landing due to fog. The aircraft was destroyed on impact and concurrent fires in parts of the wreckage were quickly extinguished by the airport fire service. Six of the 12 occupants were killed, four were seriously injured and two sustained minor injuries.

The location of the wreckage with the yellow cross marking indicating the first point of aircraft contact with the runway (reproduced from the Official Report)

Investigation

The event was Investigated by the Irish AAIU with the aid of some technical assistance provided by the UK Aircraft Accident Investigation Branch (UK) (AAIB). The Investigation established that the aircraft involved had been leased to another company which was not the holder of an Air Operator Certificate but termed by the Investigation as the ‘Owner’, who in turn sub-leased it to a small Spanish AOC holder called Flightline S.L. - the ‘Operator’ - which sold the provision of “passenger air transport service” to a ‘Ticket Seller’ based on the Isle of Man called “Manx2” which was not the holder of Air Operators Certificate. The aircraft was maintained by another (Spanish) Company termed by the Investigation the ‘Maintenance Provider’ which neither directly provided nor contracted line maintenance provision in respect of the remote operation being carried out from a base in the Isle of Man, a non-EU Territory.

The Investigation was materially assisted by the successful recovery and replay of the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR), although the Operator was unable to provide on request and as required by regulation the FDR data frame layout. The lack of this ability was found not to have been discovered during Operator quality audits or to have been made a requirement by the applicable National Regulations. Data from the Non Volatile Memory of the recovered GPWS/TAWS equipment fitted to the aircraft and ATC radar recording were also available.

It was found that after an initial wingtip contact with the intended landing runway as marked on the diagram above, the aircraft had ended up inverted some 189 metres from the initial contact point some 72 metres to the right of the runway centreline. The Investigation noted that, having first extinguished the two engine fires and taken action to eliminate any further fire risk, the Airport Rescue and Fire Fighting Services had initially forced open the rear cargo door (see the close-up picture of the wreckage below) as the main means to facilitate extrication of the surviving occupants after first removing the baggage and the divider separating the hold from the passenger cabin.

It was established that the aircraft had been engaged in night mail cargo flights for the UK Royal Mail under the terms of a contract between the aircraft ‘Owner’ and an agency working on behalf of the UK Royal Mail. The accident flight crew of two pilots had commenced duty at 0615 at Belfast Aldergrove and positioned the aircraft empty to Belfast City, where they arrived at 0715 for the scheduled 0750 departure to Cork.

An ATC FPL for the accident flight was found to have been filed three hours earlier by a Fixed Base Operator (FBO) in Billund, Denmark showing just one alternate, Waterford. The pilots had obtained TAF and Meteorological Terminal Air Report (METAR) information when beginning duty which had indicated that fog at Cork may well prevent a landing but had not obtained any other weather at that time except that for Dublin. The evidence available indicated that they had been unaware of the weather at Waterford, the single nominated alternate on the filed FPL, or that at other potential diversions - Shannon and Kerry. Given the poor weather at Cork, they were required to (re) file a FPL with two viable alternates but did not do so. Boarding of the passengers was delayed because both pilots were still securing some of the passenger seats which the off-going flight crew from the night cargo flights were supposed to have completed. It was found that none of the Operator’s pilots were trained or authorised to refit seats and that there were discrepancies between the actual and documented seating configuration on the accident flight. The required pre-fight safety briefing was given to the 10 passengers by the Co Pilot, since no cabin crew was present or required.

As the aircraft approached Cork with the Co-Pilot as PF, LVPs were in operation in fog and the crew were advised that the active runway was 35 with runway 17 available for a Cat 2 Instrument Landing System (ILS) (for which the accident aircraft / crew were not equipped / trained). An ILS approach to runway 17 was commenced and continued past the “Outer Marker equivalent point” (which determines, according to the reported IRunway Visual Range (RVR), whether an instrument approach can continue) despite the fact that the IRVR was still below that required. The approach was further continued below the applicable 200 feet DH and when a go around was eventually commenced, the lowest TAWs-recorded height was 101 feet agl. Radar vectors were then given for an approach to runway 35. The IRVR provided was again below that required but the approach was again continued both past the “Outer Marker equivalent point” and below the applicable 200 feet DH before a second go around was commenced, with the minimum recorded height in this case being 91 feet agl.

After a short time in the hold, during which ATC passed the weather at Kerry (good) and Dublin (useable but poor), a third approach was commenced, this time to runway 17. Although the IRVR had improved, it initially remained below the minimum 550 metres required before briefly reaching this but then dropping below it again prior to the “Outer Marker equivalent point”. Contrary to SOPs, the Pilot Flying (PF) and Pilot Monitoring (PM) began operating the power levers and for the third time, descent was further continued below the 200 feet DH. As the aircraft approached 100 feet agl it was found that the power levers had been selected momentarily below the flight idle stops (at 40° Power Lever Angle (PLA) into the prohibited-in-flight “beta” range where the effect of a minor but persistent continuous mismatch between the torque delivered by the two engines at any given PLA had been aggravated and a sudden bank to 40° left had followed with the left/right PLAs reaching 31/33°respectively. Almost immediately, and just below 100 feet agl, the PM had called a go around, which was acknowledged by the PF. However, “coincident with the application of go around power” by the PM, the aircraft rolled to the right as control was completely lost. It had then continued to roll “rapidly to the right beyond the vertical” reaching an angle of 97° at which point the right wingtip contacted the runway surface before continuing to roll to a maximum angle of 115° until “the aircraft impacted the runway inverted” before sliding to its final resting position.

Both pilots were found to have been employed by the ‘Owner’ rather than the ‘Operator’ but all their training and checking had been carried out by the latter. The 31 year old aircraft commander had acquired almost all of his 1801 hours of flying time as a Co-Pilot on the accident aircraft and had recently been promoted to Captain, making his first flight in that capacity four days prior to the accident. The 27 year old Co-Pilot had a total of 589 flying hours of which 289 had been acquired on the accident aircraft type. Both Pilots held JAA CPLs issued by Spain to the Captain and by the UK to the Co-Pilot. The Investigation found that neither pilot had received the minimum specified training/checking for their respective crew positions before being released to unsupervised line flying and specifically that the Crew Resource Management training specified in the Operations Manual (OM) Part ‘D’ for command upgrade had not been delivered. It was also noted that the Captain had been trained and checked during preparation for his upgrade by the same examiner, which was considered to be “contrary to good practice” - although this was noted to be a matter that had been rectified by enhanced regulatory requirements subsequent to the accident.

Although the Investigation uncovered serial non-compliance in the provision of arrangements mandated for the continuing airworthiness of the aircraft, it was concluded that the only respect in which this situation had had any direct bearing on the situation which led to the loss of control was the un-rectified slight mismatch between the power levers. However, it was found from FDR data that this fault had been present throughout the 166 hours of available recorded flight data including during normal go arounds with no obvious consequence and had not led to any defect entry being made in the Aircraft Technical Log. The Investigation therefore concluded that “this anomaly did not materially affect the normal operation of the aircraft; however when the aircraft entered a regime prohibited by the Aircraft Flight Manual (AFM), this anomaly became significant.”

It was considered likely that this throttle mismatch had been present since the return if the aircraft to service four months prior to the accident after following the failure to perform available Aircraft Maintenance Manual checks after the re-installation of both engines during a 9-month damage repair to the aircraft carried out in Germany necessary following a hard landing event in November 2009. It was attributed to a faulty sensor which would have led to slightly more fuel flow - and therefore slightly more engine torque - being delivered to the right engine than to the left at the same power lever angle.


Further Reading