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Coffin Corner

Old 22nd June 2008 | 16:09
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Coffin Corner

How is the correct way to escape from Coffin corner. Is it by Descending to a "safer" altitude while carefully controlling airspeed ?
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Old 22nd June 2008 | 16:11
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Well, we don't recommend climbing.
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Old 22nd June 2008 | 16:36
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Just don't go there in the first place. Know your buffet margins. If you are foolish enough to end up in that predicament your solution would work.
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Old 22nd June 2008 | 16:47
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No it won't! The definition of CC is that ANY increase or decrease in speed will result in loss of control, so basically you are Gordon Ramsey'd as we say on UK TV.

Sentence 1 rules.

Last edited by BOAC; 22nd June 2008 at 17:06.
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Old 22nd June 2008 | 16:51
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Surely you mean Gordon Ramsey'd. Jamie is just a cockney lad who uses slang, but he doesn't swear on TV!

Lots more power might help.
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Old 22nd June 2008 | 17:04
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Whoops! Yes I do. Thanks. Edited. I actually watch neither, so please may I be excused?
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Old 22nd June 2008 | 17:26
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BOAC what is the ans ? How does one escape without killing themselves.
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Old 22nd June 2008 | 18:56
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Actually, the term "coffin corner" refers to a very small window between mach buffet and stall, not loss of control. And it is possible to maintain a given airspeed while descending, is it not? This is a very high altitude phenomenon, so you'd likely be at a pretty high power setting and all you have to do is reduce throttle. In fact not many aircraft have enough motor to get themselves into this situation to begin with.
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Old 22nd June 2008 | 19:06
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Well

Reduce power and.... Stall. No increase left, at max altitude, can't climb, At Vne can't descend, you going to do uh What?? Including the word Coffin is not a mistake.
rubik: more power than wing has killed many an inattentive pilot.

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Old 22nd June 2008 | 19:06
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BOAC is, as ever, correct!

Why would you want to go there? You don't save fuel by climbing early above optimum.
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Old 22nd June 2008 | 19:08
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I believe the actual 'coffin corner' was a one-way street, that real control loss was supposed to happen there with ANY change in Mach or IAS. It would require consumate skill to 'lower the nose' and fly out of it without increasing Mach no or reducing IAS. I suspect it was more a notional 'media' thing rather than a real one, but I'm sure someone will know better.

Ironically, for 'rubik', "Lots more power might help." - it was the converse. Too little power stopped people from getting up there as Lear pilots have discovered the hard way.
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Old 22nd June 2008 | 19:28
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Sounds hard to reach such a critical Coffin Corner situation where ANY changes involve a Stall or Overspeed? Seems very hard to even approach this situation without stalling or overspeeding beforehand. You will always have some margin which is the way you would get out.

If you somehow get to such a critical situation I think anybody would rather have an overspeed in the recovery process than a shaker.


rcl
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Old 22nd June 2008 | 19:32
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Coffin Corner "sounds hard to reach". Only if you can't imagine flying well past it. It isn't a destination, it's no man's land. It's real, have faith and believe.

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Old 22nd June 2008 | 20:09
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In a modern Airliner you can't get near "coffin corner" without busting MMO so we should coin a new term for the limiting alt where MMO and AoA stall coincide.

Any suggestions?

How about Certifications Wall?
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Old 22nd June 2008 | 20:36
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What about

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Old 22nd June 2008 | 21:04
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redout - if you look at the bottom of the page you will see several threads about CC. Our friend John Farley posts (at #14) in one of them a good description of the situation.

Looks like your original question is best asked of a U2 pilot.
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Old 23rd June 2008 | 07:00
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Reduce power and.... Stall. No increase left, at max altitude, can't climb, At Vne can't descend, you going to do uh What?? Including the word Coffin is not a mistake. rubik: more power than wing has killed many an inattentive pilot.
Airfoil you can reduce power and use attitude to maintain airspeed. Airspeed is the critical factor.

Just don't apply for a job as a carrier pilot if you don't understand that sink can be controlled EITHER by attitude or power. You add new lustre to the term plain driver ... sorry I meant plane driver.
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Old 23rd June 2008 | 08:22
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Believe the U2 had a spread of about 10 knots.
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Old 23rd June 2008 | 08:53
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That's a big chunk of Mach, Brian - you sure? I assume that was at 'normal' operating altitude rather than any 'higher'?
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Old 23rd June 2008 | 09:06
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The Chuck Yeager Approach

To recover from CC.Tumble in an uncontrolled manner out of the sky until you hit thicker air. Ultimately you will recognise the uncontrolled state has now entered a recognisable aerobatic state (spin or inverted spin). Apply standard recovey technique. Simple.
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