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Other newsgroup: weird landing

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Hi all,In a dutch newsgroup nl.reizen (translated: nl.travel) a post was written by somebody who had a weird landing. I translated it here below. Is somebody able to explain this? 'A couple of weeks ago I flew to Moscow with a KLM B767-300. At Moscow we were not able to land immediatly, so we had to fly a circle at a hight of 7 kilometers. When almost performed the circle, the pilot brakes enormously, opens the flaps, reverses the engines. Within a couple of minutes we went from 7 km down to 2 km, and reducing speed from 780 km/h to 220 km/h. After this stunt we landed normally. Just a little white round the nose. Does anybody have a clue what happened? Was it just to make it to the runway or something else?' Origin post copied below: 'Paar weken terug met de KLM naar moskou, in een 767-300.Bij Moskou konden we niet meteen landen, dus draaide eerst een rondjeop 7Km hoogte. Bijna rond gooit de piloot ineens alle ankers uit, flapsopen,en motoren achteruit. Binnen enkele minuten gaan we van 7 naar 2 km hoogteengaat de snelheid van 780 km/u naar 220.Na deze stunt landen we verder normaal. Ietwat groen/geel, dat wel.Heeft iemand een idee of dit alleen was om de landingsbaan nog te halen, ofzou er wat anders aan de hand zijn?Ries '[/ font]

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Hallo Ferry,I seriously doubt that thrust reversers are used in full flight. What I did experience once was, due to serious medical conditions with one of the passengers on board, we had to descend as quickly as possible from FL330 to sealevel in a 737-800. This was done with all speedbrakes fully deployed, which got us down to the runway in about 10 minutes. This did cause a lot of noise and rumbling - could be mistaken for reverse thrust.Not the usual way to go really. Can't say why the rush in this particular case you mention.Cheerio,Vince

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Sometimes here in the states, ATC will say something like "KLM xxx I can sequence you for landing immediately if you can be descend to xxx immediatiely, otherewise plan to hold for 30 min." Needless to say, the pilots do what they can to make it usually. Just a guess. -------------Michael

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Strike 'seriously doubt' - there's no question, tey would have not been used (purposely) in flight :)

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Correct me if I'm wrong, but I think reversers CANNOT be deployed in the air. Again, not sure. But it would probably be lethal...Cheers,http://ftp.avsim.com/dcforum/User_files/3d68c1fb7d97da8c.jpgAA RULES!!! :)Download my semi-photoreal AA 757!:http://ftp.avsim.com/library/sendfile.php?DownloadID=16882Aerolineas Argentinas A330-200 NOW AVAILABLE!!http://www.thevivcorp.com/~fyarepaints/MyR.../posky332ar.zipChrome AA 767 NOW AVAILABLE!!http://www.thevivcorp.com/~fyarepaints/MyR...osky767aaV1.zipDominicana de Aviacion 727-53C NOW AVAILABLE!!http://www.thevivcorp.com/~fyarepaints/MyRepaints/dom722.zip______________________________"Whenever you find yourself in the side of the majority it's time to pause and reflect" - Mark Twain

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I remember an Air Lauda accident where in-flight use of reverse thrust led to a crash of the aircraft. Don't know if this was a malfunction, but even if it were possible then it's likely to be blocked now!Vince

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There are some aircraft that are certified to use their thrust reversers in flight. The 767 is not one of them. I know specifically that the DC-8 and 707 are permitted to, i suspect that there may be others as well. I would venture to say that there is not a twin engine aircraft out there certified for in flight deployment of the reversers, and more than likely there is not a tri-jet certified for it as well, but i'm just speculating now. As for the Lauda air accident, it was an uncommanded deployment of, i believe, only one thrust reverser. I believe an AD was issued as a result which installed some sort of guard or lock over the 767's reversers so as to prevent a reoccurance but i'm not sure, perhaps someone else is more familiar with the accident than i am.-Rob

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Okay, now I wanted to know so I looked it up:http://aviation-safety.net/database/1991/910526-0.htmThe official report (linked from the above page) has the FAA to mention:"The rules for thrust reverser certification assume that inflight reverser deployments will occur and they require that such deployments not result in an unsafe condition. Traditionally, this has been demonstrated by tests conducted at relatively low speed and thrust conditions supported by analytical extrapolations to all flight conditions. Service experience on many airplane models has included inflight deployments which were controllable and appeared to validate these certification procedures. These procedures were applied to the 767 certification effort, and indicated that an inflight reversal was a controllable event. The recent accident calls these certification assumptions into question. It is possible that modern high bypass engines combined with more efficient thrust reversers have resulted in aircraft which require a new thrust reverser certification philosophy. Inflight reversal, under certain flight conditions, may now be an event similar in magnitude to certain primary flight control failures which must be prevented to avoid loss of the aircraft.The Boeing Company is in agreement with the need to upgrade the level of safety of thrust reverser systems, and has been cooperating with the FAA in a review of all of their thrust reverser installations. This includes system design philosophy and system design details. This review, of course, began with the 767 due to the recent accident. "And also, in a list per aircraft type:"Boeing Model 767 airplanes powered by Pratt and Whitney PW4000 series engines:At present, all thrust reverser systems on these air planes are deactivated due to the issuance of airworthiness directive (AD) T91-18-31, dated August 23, 1991."BUT:"Boeing Model 767 airplanes powered by General Electric CF6-80C2 series and Rolls Royce RB211-524 series engines:At present, operation of these airplanes with active thrust reverser systems is permitted. It is anticipated that certain repetitive system tests and inspections will be mandated by AD action. The service bulletins necessary for these tests and inspections have already bean approved by the FAA. and AD action is planned before October 1, 1991."DO note that the report only speaks about ACTIVEness of reverse systems - not whether their deployement MAY BE COMMANDED in flight. Two other quotes set me straight on that (I was mistaken for a short while):"The Boeing B767 thrust reverser system is designed for ground operation only. Actuation of the PW 4000 thrust reverser requires movement of two hydraulic valves that are installed in series. The system has several levels of protection designed to prevent uncommanded in-flight deployment. "AND"The possibility of crew commanded thrust reverser deployment was considered. The probability of an experienced crew intentionally selecting reverse thrust during a high-power climb phase of flight is extremely remote. There is no indication on the CVR that the crew initiated reverse thrust. Had the crew intentionally or unintentionally attempted to select reverse thrust, the forward thrust levers would have had to be moved to the idle position in order to raise the thrust reverser lever(s). In addition, the air/ground system would have prevented hydraulic power from being applied to deploy the thrust reversers. Examination of the available airplane's center control stand components indicated that the mechanical interlock system should have been capable of functioning as designed."Apologies for the long post! ;-)Cheers!Vince

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