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Difference between revisions of "A332, vicinity Tripoli Libya, 2010"

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[[File:A332fpHLLT1-2.jpg|thumb|none|600px|An annotated flight profile 2/2 based on FDR/CVR data (reproduced from the Official Report, Appendix 11)]]
 
[[File:A332fpHLLT1-2.jpg|thumb|none|600px|An annotated flight profile 2/2 based on FDR/CVR data (reproduced from the Official Report, Appendix 11)]]
 
[[File:A332FltP.jpg|thumb|none|600px|Selected FDR data for the go around (reproduced from the Official Report, Appendix 10)]]
 
[[File:A332FltP.jpg|thumb|none|600px|Selected FDR data for the go around (reproduced from the Official Report, Appendix 10)]]
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It was noted that  the lack of any follow up after the unstable approach to the same runway flown by the same crew on the same aircraft two weeks earlier had removed a potentially significant opportunity for the both pilots to recognise the potential issues associated with managing non-precision approaches and the transition to any go around from one.
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It was accepted that the performance of both pilots may have been impaired by [[Fatigue|fatigue]] but the available evidence did not allow this possibility to be confirmed or eliminated. [[link to Appendix 7]] 
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It was considered that whilst the go around could have been performed with the AP remaining engaged, the First Officer’s choice of manual control ''“may be explained as a response to an emergency”'' as if a TAWS ‘PULL UP’ warning rather than the ‘TOO LOW TERRAIN’ alert which had actually occurred.
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Overall, it was concluded that evidence led to a conclusion that the go around had been attempted without the Captain having fully engaged with the change from his previous expectation of a landing.
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The question of inaccurate surface weather reports and broadcasts was considered. It was clear that, in respect of the prevailing visibility as the accident aircraft approached, evidence from the crew of the aircraft which landed just before the crash and another that was allowed (despite the degraded fire cover) to take off just after it was that the real cloud cover and visibility were not being reported by [[METAR]] / [[ATIS]].
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The pilot of the aircraft ahead of the accident aircraft on approach that landed on runway 09 four minutes before the accident and had advised on frequency of ''“fog patches beginning to form”'' advised the Investigation that although when he initiated the final descent, he could see the airport and the runway lights through the mist, he had ''“then passed through a more or less dense cloud layer that he considered to be low stratus cloud. Close to the minimum descent altitude, he regained sight of the ground and landed”''. He had also suggested to ATC once parked that the runway in use should be changed and when he had heard the missed approach call, had thought this manoeuvre was due to his message about the weather conditions.
  
  
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==Further Reading==
 
==Further Reading==
 
*[[Crew Resource Management]]
 
*[[Crew Resource Management]]
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*[[Fatigue]]

Revision as of 16:13, 27 March 2013

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Description

On 12 May 2010, an Airbus A330-200 being operated by Libyan airline Afriqiyah Airways on a scheduled passenger flight from Johannesburg to Tripoli with a cruise relief First Officer on board and observing in the flight deck for the approach, commenced a go around in day Instrument Meteorological Conditions (IMC) after failing to obtain the required visual reference to land following a non precision approach to runway 09. However, soon afterwards, it crashed short of the intended landing runway just outside the aerodrome perimeter and was destroyed by the impact and subsequent fire with all but one of the 104 occupants being killed.

Investigation

An Investigation was carried out by the Libyan Civil Aviation Authority. Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data was successfully downloaded from the recovered recorders. It was noted that both pilots and the observing relief First Officer had recorded exactly the same A330 flying hours total of 516 since qualifying on type at the manufacturer’s training facility the previous year and had all been previously rated on the Airbus A320.

The impact site was located 1200 metres from the threshold of the runway to which the approach had been made and 150 metres to the right of its extended centreline just outside the airport perimeter - see the diagram below taken from the Official Report. It was noted that the time of sunrise was ten minutes after the accident occurred, a time of day and year when fog and / or low Stratus cloud was not unusual, although not forecast on the day of the accident.

Accident site and aircraft ground track to it (reproduced from the Official Report)

It was established that the First Officer had been PF and had flown a L/DME approach - see the chart below. Prior to commencement of this approach, the surface weather report had been given as ‘visibility 6km, sky clear’ and the applicable TAF was showing a ‘PROB 40’ of 5000 metres visibility in mist. Whilst the aircraft was on the approach and below 1200 ft Altimeter Pressure Settings, an aircraft which had just landed advised of fog patches beginning to form on the approach. As the aircraft passed 1000 feet QNH, the crew confirmed to ATC that they would report the runway in sight to obtain landing clearance.

The chart for the L/DME 09 approach procedure as flown (reproduced from the Official Report)

With no response by the Captain to the automatic annunciation ‘MINMUM’ as the applicable MDA of 620 feet QNH (410 feet agl) was passed, the PF had then asked the Captain if the approach should be abandoned and followed this with a repeat of the automatic ‘THREE HUNDRED’ computer callout which had, by then, just occurred, the GPWS/TAWS “TOO LOW TERRAIN” alert activated and this appeared to have prompted the Captain to call a go around. This call was acknowledged and the go around initiated by the PF from 490 feet QNH (280 feet agl) with AP disconnection, Take-off / Go-around (TO/GA) Mode selection, and landing gear retracted.

Although the go around was initiated promptly and positively by the PF, only four seconds later, he had begun to apply nose-down inputs on his side stick, resulting in a decrease in the pitch attitude of the aircraft until it became negative. The maximum altitude reached was only 670 feet QNH (450 feet agl). It was considered that these continued inputs had been “consistent with the high pitch attitude he could have perceived (and) typical of a somatogravic perceptual illusion occurring in the absence of outside visual references and (a failure to monitor) the artificial horizon”. It was noted that the PF “would have maintained nose-down inputs as long as he was feeling this effect, the pitch attitude perceived being relatively constant and greater than the theoretical pitch attitude during a go-around”. link to Appendix 6

It was surmised that the PFs successive callouts of ‘Flaps’ at this point may well have been “due to his detection of the red and black stripe on the speed tape and the very high speed trend due to acceleration”. It was further considered that this apparent ‘tunnel vision’ of the speed trend at the expense of the more central indication of the increasingly unfavourable aircraft attitude was indicative of a desire to avoid replicating what had happened during a go around from an unstable approach to the same runway with the same crew two weeks earlier during which the over speed warning had been was activated. This event had been identified by the Operator OFDM system but no follow up action had been taken by the time of the accident approach.

As the aircraft had begun to descend from 450 ft agl, it was noted that “neither crew member seemed to be aware of the flight path of the aircraft”. The Captain had responded to the PFs ‘Flaps’ calls and spoken to TWR but was not monitoring the flight path. As the aircraft descended again through the MDA equivalent 410 feet agl and the automatic ‘MINMIMUM’ Call activated again, there was no recorded response from either pilot.

It was found from FDR data that, from the point of go around onwards, the Captain had begun making small inputs to his side stick, but these had not been sufficient to trigger the ‘Dual Input’ Alert. It was considered that the available evidence indicated that, “like the PF, the Captain’s attention appeared to be focused on the speed tape”. He had called ‘Speed’ and had pulled the Speed/Mach button on the FCU to select the current speed at 176 KCAS when the speed trend was still mainly in the red band. It was considered possible that the Captain also wanted to avoid triggering the over speed warning with a similar recollection of the earlier approach.

Finally, “three seconds after having selected the speed on the FCU and during the seven seconds before the aircraft struck the ground, a succession of TAWS alerts and warnings of increasing severity was recorded. In response to the first of these, the Captain had applied a sharp nose-down input followed immediately by a contrary pitch-up input by the First Officer. The Captain maintained his nose-down input on the side stick whilst taking side stick priority so that the effect of First Officer’s side stick selection to the pitch-up stop was negated.

At about 180 feet agl, less than two seconds before impact and one second after the last TAWS ‘PULL UP’ warning was triggered, the Captain had applied a pitch-up input to the stop and released the priority side stick push button with the First Officer’s side stick input also to the pitch-up stop. It was considered that these inputs probably indicated that the two operating crew members had finally become aware of the aircraft path and ground proximity. However, it was seen from the data that the Captain had reversed his pitch-up input to a pitch-down input one second before impact.

In respect of the flight crew performance, it was noted that the approach brief given had been minimal and selective. Initially, although there was some evidence of non standard flight management with the AP engaged, exchanges between the two pilots “suggest that at this stage of the flight, both crew members shared the same approach strategy”. Thereafter, although the PF was clearly focused on his task, Crew Resource Management was not very effective and it was considered that in the latter part of the approach, “the pilots no longer seemed to share the same strategy for conducting the final approach” and that meaningful CRM had effectively ceased as soon as the go around had been initiated.

The vertical profile shown below was included as Appendix 11 to the Report and is based on consolidated data from the FDR and CVR summarises the approach and go around sequence leading up to impact. The third illustration, Appendix 10 to the Official Report, shows selected FDR parameters for the go around and adds a modelled representation of perceived pitch due to the effects of somatogravic illusion for comparison with actual pitch.

An annotated flight profile 1/2 based on FDR/CVR data (reproduced from the Official Report, Appendix 11)
An annotated flight profile 2/2 based on FDR/CVR data (reproduced from the Official Report, Appendix 11)
Selected FDR data for the go around (reproduced from the Official Report, Appendix 10)

It was noted that the lack of any follow up after the unstable approach to the same runway flown by the same crew on the same aircraft two weeks earlier had removed a potentially significant opportunity for the both pilots to recognise the potential issues associated with managing non-precision approaches and the transition to any go around from one.

It was accepted that the performance of both pilots may have been impaired by fatigue but the available evidence did not allow this possibility to be confirmed or eliminated. link to Appendix 7

It was considered that whilst the go around could have been performed with the AP remaining engaged, the First Officer’s choice of manual control “may be explained as a response to an emergency” as if a TAWS ‘PULL UP’ warning rather than the ‘TOO LOW TERRAIN’ alert which had actually occurred.

Overall, it was concluded that evidence led to a conclusion that the go around had been attempted without the Captain having fully engaged with the change from his previous expectation of a landing.

The question of inaccurate surface weather reports and broadcasts was considered. It was clear that, in respect of the prevailing visibility as the accident aircraft approached, evidence from the crew of the aircraft which landed just before the crash and another that was allowed (despite the degraded fire cover) to take off just after it was that the real cloud cover and visibility were not being reported by Meteorological Terminal Air Report (METAR) / Automatic Terminal Information Service (ATIS).

The pilot of the aircraft ahead of the accident aircraft on approach that landed on runway 09 four minutes before the accident and had advised on frequency of “fog patches beginning to form” advised the Investigation that although when he initiated the final descent, he could see the airport and the runway lights through the mist, he had “then passed through a more or less dense cloud layer that he considered to be low stratus cloud. Close to the minimum descent altitude, he regained sight of the ground and landed”. He had also suggested to ATC once parked that the runway in use should be changed and when he had heard the missed approach call, had thought this manoeuvre was due to his message about the weather conditions.


Further Reading