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Aviation History
1979
1979 - 0201.PDF
FLIGHT International, 20 January 1979 195 We guess that Gapt Grubbs did not want to risk damaging his tyres, perhaps cutting them: on taxi lights, in the 146° turn that would be needed at C3 (see diagram). If he had taken the third turning, the KLM 747 would probably have just cleared the Pan American aircraft and a terrible tragedy would have been merely a frightening near-miss. But the Pan American captain's reasons are not examined by the report. There are other examples of the report's superficiality and subjectivity. The Spanish controller, it says on page 59-60, "who had not been asked for take-off clearance, and who consequently had not granted it, did not understand that they were taking off." This gives the impression that there is R/T phraseology to request take-off clearancei, and that this was not used by the KLM crew. This is not cor rect; Icao document Pans-Rac states clearly on page 9.1 para 2.3 that there are no phraseologies laid down for use by aircraft, only for use by ground stations. This is bad, of course; but instead of suggesting that the KLM captain was to blame for not following procedures, why not point out the shortcomings of Icao phraseology so that we can make it safer for the future? The report overlooks the fact that the Spanish controller gave neither KLM nor Pan American any information about winds, QNH, visibility, temperature or time in accordance with Icao procedures as set out in Ioao document Pans-Rac and for which standard phraseology is laid down. Again, the "OK" of the Spanish controller which acknowledges the KLM takeroff transmission is not as "irrelevant" as the report wants us to believe (page 60). The word "OK" was followed by a pause of nearly two seconds. The report surely cannot exclude the possibility that such a word, especially followed by a pause, could have strengthened the (wrong) opinion of the KLM cap tain that he was cleared for take-off, even though he was by then rolling. Pages 35-38 consider the human factors which may have put the KLM crew under stress. These may he relevant (though some are quoted as if they were fact rather than assumption). But why were not such factors equally valid for the crew of the Pan American 747, and for the air traffic controllers? On page 38 it is said that similar training is carried out without take-off clearances, but this is definitely not true of KLM simulator training. The emphatic confirmation "Jarwel" by the captain might be said to indicate how certain he was that the run way was clear when the KLM flight engineer, on hearing Pan Am's "OK, will report when we're clear" asked him, after he had already released the brakes and opened the throttles, "is he not clear then? ... Is he not clear, that Pan American?" Instead the report suggests that the cap tain was in some way pulling rank (page 48). The tower's "OK . . . Stand by for take-off" transmission was overlapped by PAA's "we are still taxiing down the runway", causing a "shrill noise" (also described as "a whistling sound") in the KLM cockpit. How can the report then assert that a "fundamental cause" of the accident was that the KLM pilot "did not obey" the "stand by for take off" from the tower? By all means blame the pilot, alive or dead, if he was to blame; but to do so in this way is of poor service to air safety. Q The Spanish report The significant evidence, as always when it is available, comes from the cockpit voice recorders, tower tapes and flight-data recorders. •At 1705:27.08, KLM 4805, which was already at the approach end of runway 30, completed the turn in order to face in the direction for take off ... At 1705:27.98, the engine braking begins and lasts for 2.54 seconds. At 1705:35.7, the co-pilot finishes the take-off check list and at 1705:41.22 (67.81 seconds before the impact), a slight for ward movement due to opening of the throttle is observed (increase of continued EPR in the four engines). At 1705:41.5, the co-pilot says: "Wait a minute, we don't have an ATC clearance." To which the captain replies, "No, I know that, go ahead, ask." At 1705:44.6, KLM 4805 tells the control tower: "Ah—the KLM four eight zero five is now ready for take off, and we're waiting for our ATC clearance." This message ended at 1705:50.77. This communication was heard in the PAA 1736 cockpit. At 1705:53.41, the controller gave KLM the following ATC instructions: KLM eight seven zero five'—uh—you are cleared to the Papa beacon climb to and maintain flight level nine zero . . . right turn after take off proceed with heading zero four zero until intercepting the three two five radial from Las Palmas VOR." The message ended at 1706:08.9. At 1706:07.32, i.e., 0.7 seconds before the message ended, the aircraft captain said, "Yes," and 44.31 seconds before the impact the nos. 3 and 4 engines slightly increased their EPR. At 1706:09.61, the co-pilot repeated the ATC instruction given by the tower controller, at the following times and as follows: This simplified chart of Tenerife Airport is based on Jeppesen. It shows the turn-offs that were so critical in the accident
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