{"id":1470,"date":"2019-04-30T10:04:57","date_gmt":"2019-04-30T10:04:57","guid":{"rendered":"https:\/\/chrisbart.com\/?p=1470"},"modified":"2019-04-30T11:22:06","modified_gmt":"2019-04-30T11:22:06","slug":"737-kegworth-crash-in-1989-uk","status":"publish","type":"post","link":"https:\/\/chrisbart.com\/reviews\/2019\/04\/30\/737-kegworth-crash-in-1989-uk\/","title":{"rendered":"737 “Kegworth” crash in 1989 (UK)"},"content":{"rendered":"\n
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This crash where a new version the 737 came down on a motorway just short of the diversion airport after the captain had shut down the good engine in the belief–based on his knowledge of the previous version–that the smoke must be coming from that one.<\/p>\n\n\n\n
Furthermore, the pilots had felt the vibration and aircraft shudder, but did not refer to the engine vibration indicators clearly showing which engine had the problem because they had got out of the habit of doing so because the ones in the previous version were unreliable.<\/strong> This was not true for those in the new version of the 737.<\/p>\n\n\n\n
When the problem engine failed completely they were too low on their approach to the airport and going too slowly to restart the good engine.<\/p>\n\n\n\n<\/figure>\n\n\n\n
Extract from Air Crashes and Miracle Landings (85 Cases):<\/p>\n\n\n\n
In total, forty-seven passengers perished,\nsixty-seven passengers and seven crew members were seriously injured, and four\npassengers and one crew member had slight or no injuries. Though considered the\nclassic case of what not to do, there were a number of contributory factors to\nwhat came to be called the Kegworth Air Disaster, in view of its proximity to the village of\nthat name. These include the following:<\/p>\n\n\n\n
1. \nFalse positive \nSafety expert Professor Peter Ladkin says this is the only case he\nis aware of where a \u201cfalse positive\u201d features in an air accident. That is to\nsay the mistaken corrective action (shutting down the good engine) seemed to be\nsolving the problem, thus making the pilots think they had done the right\nthing. This is unlike in medicine, where the long period of time over which\nrecovery or improvement of the patient for any unrelated reason can be\nattributed to action by the doctor or surgeon means such false positives are\nwell known.<\/p>\n\n\n\n
\nThe cessation of the vibrations was one thing, but to confirm things by\nsaying that the smoke disappeared when the pilots shut down the number two\nengine was, with hindsight, rather dubious thinking, since smoke would not\nnormally disappear immediately.<\/p>\n\n\n\n
2. \nEngine instrument system (EIS) difficult to read \nBefore the introduction of two-man flight crews, the primary instruments,\nshowing the performance of the engines were in front of the pilots, and the\nsecondary instruments, indicating the condition of the engines, such as oil\ntemperature and pressure and vibration, were in front of the flight engineer. However,\nwith the sidelining of the flight engineer, these secondary instruments had to\nbe in front of the pilots.<\/p>\n\n\n\n
\nIn the earlier version of the aircraft, the B737-300, this was done by\nhaving traditional cockpit dials with mechanical hands, as in traditional\nclocks, there being two panels side by side, one with the main flying\ninstruments, and the other showing the condition of the engines. These earlier\nones with needles were easy to read at a glance.<\/p>\n\n\n\n
\nHowever, as anything mechanical is liable to go wrong and anyway\nrequires costly maintenance, LEDs were used instead of mechanical hands.\nHowever, rather than redesigning the panels to take full advantage of the\nvirtues of an electronic display, the designers wanted to maintain the same\ngeneral layout so pilots could switch from one model of the aircraft to another\nwithout expensive recertification.<\/p>\n\n\n\n
\nIn reality, LEDs could not simulate the previous clocklike hands,\nbecause those available at that time could not be bunched up at the center of the\ndials to look like a continuous line. Instead, the designers placed three\nrather pathetic-looking LEDs at intervals around the perimeter of the dials. <\/p>\n\n\n\n
\nThese could still be read by pilots with good eyesight when looking for\na particular reading but made comparison and noticing anything unusual more\ndifficult. In addition, Boeing had reduced the size of the secondary engine\ndisplay relative to that for the primary display instruments.<\/p>\n\n\n\n
\nThe captain and first officer had very little experience (twenty-three\nand fifty-three hours respectively) on the 737-400 version, and the airline did\nnot yet have a simulator where they could have practiced using the new engine\ninformation system (EIS), with its diodes. In addition, the captain said his\nconsiderable experience with other aircraft had led him to distrust vibration\nreadings in general, and he did not include them in his usual scan of the\ninstruments. His conversion training had not included instruction that\ntechnical improvements meant that spurious vibration readings were very\nunlikely.<\/p>\n\n\n\n
3. \nTraining and checklists \nIn the training of the BMA 737 pilots, the need to think or check things out\nbefore taking precipitous action was stressed, but as already mentioned there\nhad not been training on a flight simulator with the new hybrid EIS display.\nThere was a checklist for what to do in case of vibration from the engines and\none for what to do when smoke occurred, but not one for when they happened\nsimultaneously. <\/p>\n\n\n\n
\nAt the time pilots at BMA had not been made fully aware that there was\nno need to shut down engines completely because of vibration, nor that engine\nfans which are vibrating or not properly aligned could have their fan tips\ntouching the rubber seals on the periphery and that this could produce smoke\nand a smell of burning but did not mean the engine was on fire. Thus, as the\ninvestigators said, the situation was outside the pilots\u2019 experience and\ntraining.<\/p>\n\n\n\n
4. \nWorkload and stress: Fear of fire \nIn many emergencies, airlines usually insist that captains take control.\nCaptains also tend to take control in difficult situations when it is not quite\nan emergency. Doing something physical makes the captain feel he is coping and\nrelieves stress. The trouble with this is that the captain is concentrating on\nthe physical task of flying the aircraft, or, as in the case of SQ006 at\nTaipei, maneuvering it over the slippery taxiway in bad visibility and heavy\nrain, and misses the larger picture. <\/p>\n\n\n\n
\nThe flight data recorder (FDR) revealed that when the captain disengaged\nthe autopilot, the aircraft yawed sixteen degrees to the left, a sign that the\nleft engine was producing less power than the one on the right, but he did not\nseem to notice, as he did nothing to correct it. The fact that the first officer\nreported to ATC early on that they had an \u201cemergency situation like an engine\nfire\u201d shows they were concerned about fire, even though up to then none of the\nengine fire alarms had triggered.<\/p>\n\n\n\n
\nIt is an interesting psychological point that a smell can instantly\ntransport one mentally to a certain place, and the shaking of the aircraft\nfollowed by the smell of burning may have caused the pilots to react more\ninstinctively and precipitously than they would have done in the event of a\nfire-warning light coming on. Anyway, a fire warning would have immediately\nindicated which engine had the problem.<\/p>\n\n\n\n
\nThe official report made the additional point that having another pilot\ntake over the handling of the aircraft\u2014as PF (pilot flying)\u2014meant monitoring of\nthe instruments was less consistent than it might have been. <\/p>\n\n\n\n
\nUp until the onset of the vibration, the first officer had been flying\nthe aircraft and would have been concentrating on the main instruments, not the\nengine vibration indicator, it being the role of the PNF (pilot not flying; in\nthis case the captain, who did not believe in scanning vibration readings) to\ndo the general monitoring. The captain must have thought the first officer had\ngood reason to say it was the right engine that was giving trouble.<\/p>\n\n\n\n
5. \nUnfortunate timing. <\/p>\n\n\n\n
\nThe pilots did not have the height or speed to restart the good engine,\nand not enough height to choose a flat place to land. Had the airport been\nfarther away, they would have had found the problems with the number one engine\nwhen still high enough to restart the other one.<\/p>\n\n\n\n
6. \nPassengers and three cabin crew knew \nPassengers at the rear who had seen the \u201csparks\u201d from the left engine when the\ninitial trouble occurred were somewhat perplexed when the captain said he had\nshut down the right engine but did not inform the cabin crew because the\ncaptain sounded supremely confident. <\/p>\n\n\n\n
\nThe three members of the cabin crew who had also seen the sparks\napparently did not notice the captain saying the right engine had been shut\ndown. They knew the purpose of the announcement was to reassure the passengers\nand were no doubt extremely busy with their own duties as they got ready for\nthe unexpected landing.<\/p>\n\n\n\n
A retired British Airways flight\nattendant has suggested to the author that the failure to pick up on the\ncaptain\u2019s mistake might have come about because cabin staff themselves often get\nconfused about left and right, as they face backwards when addressing the\npassengers.<\/p>\n\n\n\n
Just\nafter shutdown of the number two engine, the captain called the flight service\nmanager (FSM) to the flight deck to tell him to clear things for landing, and\nat the same time asked him, \u201cDid you get smoke in the cabin back there?\u201d He got\nthe reply \u201cWe did. Yes.\u201d<\/p>\n\n\n\n
This\nperhaps only confirmed the captain\u2019s mistaken view that the right-hand engine\nmust have been at fault. The FSM departed but returned a minute later to say\nthe passengers were panicky, and it was only then that the captain announced to\nthe passengers that a little trouble with the right engine had produced some\nsmoke, but it would be okay, as they had shut it down, and would be landing\nabout ten minutes thereafter.<\/p>\n","protected":false},"excerpt":{"rendered":"
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