Air NZ DC10 (Mount Erebus, Antarctica)

Transcription

1 Copyright Avfacts Al rights reserved. Accidents page 1. Additional Information to that presented via the Links. Air NZ DC10 (Mount Erebus, Antarctica) Confirmation Bias The flight deck crew were looking for certain visual features that would confirm the Inertial Navigation System (INS) position. The INS system picks up position errors with time in flight. Unfortunately as you have read, the INS coordinates were altered the night before the flight, and the crew not informed. The aircraft was in the inertial described position, and the crew identified the bare stone cliffs either side of the southbound track. The problem was that the bay they were flying into had stone cliffs with extremely similar scale size and shape as those on approach to McMurdo Sound. To the flight crew, and the guide this confirmed their expectancy that they were on course, when in fact they were not. In human factors this is called confirmation bias. Ahead in the clouds lay Mt Erebus. Whiteout/Flat Light Conditions As the aircraft was beneath a virtually solid cloud-base as it approached snow covered Mt Erebus the crew could not see the mountain because light travelling between the aircraft and the mountain was reflected back thus hiding textures, and horizons and contours. The cloud looked like snow and the snow looked like cloud - the crew could not tell the difference. Eventually, and too late, the FO it seems recognised the faint outline of a mountain ridge above them but at about that time the GPWS warning went off. The crew pitched the aircraft up and applied full power as trained to do, but the terrain gradient exceeded the climb gradient of the aircraft and the aircraft impacted the ground in a nose-up attitude. GPWS Limitation Approaching rapidly rising terrain (such as a cliff) GPWS can not provide a timely warning. This was the case at Mt Erebus, further dooming the flight. Light reflected back to aircraft. Light in toward the mountain Whiteout Condition (Flat light).

2 Copyright Avfacts Al rights reserved. Accidents page 2. United Airlines - Flight 173 (Portland, USA) Pecking Away at a Problem The Captain continued to mull over the problem long after all that could be done had been done. Initially he displayed good judgement in entering a holding pattern so as to sort out the problem, having been advised they had about enough fuel for 1 hour of holding. He contacted the ground engineers to seek advice and guidance. He flight engineer made a number of trips to the aircraft cabin to brief the cabin crew on the progress and procedures, perhaps too many trips in fact. He was away from his station for prolonged periods. Non-Assertive Flight Engineer Having initially advised the Captain of the fuel state, the flight engineer did not effectively give progress reports of fuel state. The Captain was advised of only 2-3 minutes fuel remaining, but just said OKAY and went back to the landing gear problem. He did not take it in. B747 (Teneriffe Canary Islands) Authority Gradient The FO was the most junior on the KLM B747 fleet, and the Captain the most senior. This causes an adverse (steep) authority gradient, and can inhibit junior crew to speak up for fear of challenging a senior crew member. Lack of Recent Line Flying The Captain was a simulator instructor and his recent experience had mostly been in the simulator, without ATC interaction, except those clearances issued by the Captain. The Captain powered up for takeoff, and to his credit the FO reminded him they did not have takeoff clearance yet. Communication Misunderstanding The ATC wording in the airways clearance including the phrase After takeoff seems to have latched in the Captains mind as a takeoff clearance when it was not. ATC airways clearances now avoid these words - a lesson learned from this accident. The FO having stopped the Captain once, perhaps felt like he could not stop him beginning the take off a second time, though doubts lingered about the Pan Am aircraft having cleared the runway. Communication Failure Interference on the VHF channel prevented the Pan Am pilots report that they were still on the runway from being heard by the KLM crew after they began the takeoff roll. It came as a complete surprise to the KLM Captain when the Pan Am B747 appeared out of the fog just ahead of them.

3 Copyright Avfacts Al rights reserved. Accidents page 3. Air Florida Flight 90 Taxiing in Icing Conditions The EPR probe on A B aircraft that sends inlet pressure information to the EPR gauge is about the diameter of a drinking straw. A very small amount of ice can block it. When this happens the EPR over-reads significantly. The power set for takeoff was actually less than that normally used in the cruise, though both EPR gauges showed a higher power setting than actual. Not having the anti-ice set ON allowed freezing water blown up from the jet exhaust of the preceding aircraft to strike the EPR inlet, thereafter it froze. Taxiing too close behind the other aircraft exacerbated the problem, though ironically the Captain thought it would help keep the ice off the aircraft. Non-Assertive Pilots The first officer was flying the aircraft. He had concerns that the aircraft was not accelerating as it should, and that the other engine instruments (fuel flow, exhaust gas temperature, RPM) showed lower than normal readings for the EPR that was set. Confirmation bias played a part also, because the crew apparently put the low EGT down to the low ambient intake temperature. Non-Assertiveness by the crew when they were obviously concerned was the final element that sealed the flights fate. Under Time Pressure Washington National airport had been closed for the last few hours due to snowstorms and snow build-up on the runways and taxi-ways, and this had delayed the flight significantly. De-Icing had occurred quite some time before takeoff and had exceeded the hold-over times specified for the fluid used. Any ice clinging to the aircraft would increase drag and reduce lift, though this alone was not considered enough to bring the aircraft down. Not selecting the Anti-ice ON, and this not being confirmed visually by both pilots was a root cause, but non-assertiveness was the final straw.

4 Copyright Avfacts Al rights reserved. Accidents page 4. British Midland B737 (Kegworth, UK) Poor Instrument Design The crew had very recently converted from a B which features large round solid engine instruments, to the 400 that had a electronic screen conveying engine parameters. The 400 engine instruments were much smaller and thinner making them harder to read. This came in for heavy criticism. Inadequate Conversion Training Over-worked Pilots ATC continually bombarded the crew with options, and requests for information (such as numbers of people on board. Something which could have been obtained from the airlines dispatcher). Lack of Cabin Crew Input The Captain announced to the passengers that he had shutdown the right-hand engine. The cabin crew noticed sparks coming from the left engine, but did not challenge the flight crew about this apparent discrepancy. Vibration Meter Limitations Vibration is often a warning that an engine is not healthy. Older aircraft had vibration meters that were somewhat unreliable, and faith was not high in these. The B had very accurate meters, but the crew were not made aware of this in the conversion briefing. Had they believed the vibration meter readings they could have questioned their engine selection. Eastern Flight 401- Florida Everglades (Lockheed Tristar) Who s Minding The Shop?? Pre-occupation by three crew members about a 50 cent light bulb brings down an airliner because the Captain did not divide up responsibilities. No one was monitoring the flight progress. The autopilot had disengaged without anyone noticing, and the aircraft hit the ground in a gentle left-hand turn. AVIATE-NAVIGATE-COMMUNICATE

5 Copyright Avfacts Al rights reserved. Accidents page 5. Saudi Flight 163 (Lockheed Tristar) Acting on Fire Warning It was over 4 minutes after the fire warning first appeared that the Captain decided to turn back to Riyadh Airport. Collectively that added 8 minutes to the flight time to get the aircraft back on the ground and evacuated. Had the decision to return been made promptly then the end result would have been different. Adding to this was the report from the flight engineer that there was not a fire at all, and he was dismissive of it. A word to the wise - If there is any doubt land ASAP. Resignation as to Their Fate There was some suggestion that the mentality on the part of the Captain was if it happens, it is God s will, and I can do nothing to counter it. Lockheed 188 Electra - Reno Nevada 1985 Lockheed 188 Electra Get The Show On the Road A major contributing factor was the Captains attitude. He was considered arrogant and belligerent and dismissive. That day he was angry because the flight was delayed, and he pushed the ground crew such that one handler forgot to close the air start access panel. Rushed Takeoff The aircraft began it s takeoff roll a mere 2 minutes and 10 seconds after the beginning of the engine start sequence. The Lockheed L188 has 4 turboprop engines. The Captain inadvertently flew the aircraft into the ground whilst turning downwind. The Captain was in a hurry to get to the cemetery to avoid the rush it seems. END