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On 2008-04-24, Brian wrote:
Depends on what you mean by "the impossible turn". If you mean turning back at 200 AGL, yeah, that one's pretty much impossible. If you mean 600 AGL, it's pretty much possible in the average aircraft. (Hell, that's pattern altitude at EFD!) The line lies somewhere in between. It is statements like this that get pilots killed. It's statements like 'never turn, always land straight ahead' that also gets pilots killed. There are plenty of airfields where going straight ahead is quite possibly the worst option, and the best survivability options are at least a 120 degree turn away from whatever point you're at when at 600' AGL. The only thing you can do is use the best judgement at the time. You get one chance - it may be wrong. Sometimes, trying to turn back might be wrong. Sometimes doing anything *other* than trying to turn back might be wrong. In gliders, every glider pilot is taught "the impossible turnback" from 200 feet (which, in the typical low performance training glider, is about equal to turning back at 600 feet in a C172). We actually train for it for real - there's no other way to do it - the instructor will eventually pull the bung on you at around 200ft. It's an essential skill because power failures (rope or cable breaks) are a lot more frequent than engines quitting on a single. Doing it off a simulated winch launch failure is quite exciting - we tend to do that at about 400 ft though because it's an extremely critical manoevre, since you're pitched up at 50 degrees or so and any delay equals a low altitude stall. The ground looks really, really close when you pitch down steeply to quickly regain your airspeed and can see nothing but green in front of you. The really important bit about this training though is you're not taught it as an absolute. The mantra is to first do what it takes to maintain airspeed, then quickly decide on a course of action. The course of action could be any of several possibilities - can you get down on the remaining runway? Can you turn back? Is what's in front of you landable? Land to the side? Which way is the wind going? (If there's a crosswind aloft, this affects the decision on which way you're going to turn: you should have already decided turn direction in the 'eventualities' part of the checklist before the slack is even taken up on the cable or tow rope). The answer is as always training, and having a plan. Think of the eventualities just as you line up - if you lose power at point X, what should you do. At point Y, what should you do? What about point Z? -- From the sunny Isle of Man. Yes, the Reply-To email address is valid. |
#2
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On Apr 25, 3:12*am, Dylan Smith wrote:
On 2008-04-24, Brian wrote: Depends on what you mean by "the impossible turn". If you mean turning back at 200 AGL, yeah, that one's pretty much impossible. If you mean 600 AGL, it's pretty much possible in the average aircraft. (Hell, that's pattern altitude at EFD!) The line lies somewhere in between. It is statements like this that get pilots killed. It's statements like 'never turn, always land straight ahead' that also gets pilots killed. There are plenty of airfields where going straight ahead is quite possibly the worst option, and the best survivability options are at least a 120 degree turn away from whatever point you're at when at 600' AGL. The only thing you can do is use the best judgement at the time. You get one chance - it may be wrong. Sometimes, trying to turn back might be wrong. Sometimes doing anything *other* than trying to turn back might be wrong. In gliders, every glider pilot is taught "the impossible turnback" from 200 feet (which, in the typical low performance training glider, is about equal to turning back at 600 feet in a C172). It's the L/D that makes it much harder in a typical powered plane. This means that all manouvers lose energy much faster. The turn back needs at least 2 turns as well as acceleration if there is any wind. You will note that nearly all the accidents are stall spins -a moments thought about the situation will make you realize why this is. The turns are made tight because there is not enough height/time for a lazy turn. Let's work some real numbers for a 172 at 500'. Say climb was a Vx 59 knots. The plane must first be accelerated to 65 for best glide. The pilot carries out some trouble checks say 10s. Calls on the radio =10 s and plans his return. Note that 20s have probably elapsed. The plane has already travelled ~0.4 miles and at a 10:1 glide ratio has lost 200' (assuming he did get it to best glide in the first place). Can he make 2 turns and land back -no way! Ah you say, I'm a much better pilot, I would loose not more than 10 seconds in starting my turn back., trimming etc. But how much does the turn back cost? Assuming you keep to 45 degrees of bank to stay _above_ stall (the stall is now damn close -better hope there's no significant wind) the turns are still going to cost you 35 seconds. 45 seconds lost = 450 feet! Now we add in the energy losses from having to accelerate with the wind and to glide speed. It's still an impossible turn. Try to tighten that turn more and you have to dive to accelerate to avoid the stall and what does that do to your energy management and turn radius? Now what safety margin is appropriate for you and you PAX? Say 100% in that case, unless you've climbed to 1000' don't even think about turning back but practice spotting good landing sites. I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! Put it down flat in landing config and you will probably survive, stall spin and you'll DIE along with your PAX. A good pilot looks at the airport environs in a strange airport and may ask about options at the runway end for this emergency. Cheers |
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WingFlaps wrote:
I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. |
#4
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Shirl wrote:
WingFlaps wrote: I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. This guy ended up in somebody's yard and missed all the suburban traffic last year. I drove through the neighborhood (about a mile from my house) to see if it's where I'd have landed. Hmm. http://www.nwcn.com/statenews/oregon....3a6a3952.html " FAIRVIEW, Ore. -- A pilot flying a small plane he had purchased just minutes earlier crash-landed in a dense suburban neighborhood near the Troutdale Airport Wednesday after the plane's engine quit. " |
#5
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Shirl wrote:
WingFlaps wrote: I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. |
#6
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B A R R Y wrote in news:Z%iQj.22374$%41.15539
@nlpi064.nbdc.sbc.com: Shirl wrote: WingFlaps wrote: I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. Exactly. Bertie |
#7
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![]() "Bertie the Bunyip" wrote in message ... B A R R Y wrote in news:Z%iQj.22374$%41.15539 @nlpi064.nbdc.sbc.com: Shirl wrote: WingFlaps wrote: I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. Exactly. Bertie One doesn't equal the other moron. |
#8
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"Maxwell" luv2^fly99@cox.^net wrote in news:YbkQj.67982$y05.56887
@newsfe22.lga: "Bertie the Bunyip" wrote in message ... B A R R Y wrote in news:Z%iQj.22374$%41.15539 @nlpi064.nbdc.sbc.com: Shirl wrote: WingFlaps wrote: I've also heard a lot of BS in this thread about not having good palces to put the plane. There is nearly always somewhere flat to put the plane within 90 degrees of the runway centerline -even a road. Malls have big parking lots! I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. Exactly. Bertie One doesn't equal the other moron. Obviously, fjukktard. Figured out that maze on the back of your froot loops box yet? Bertie |
#9
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Shirl:
I don't know about where you live, but malls here have lots of light poles, concrete islands, park-and-rest benches and ... and ... vehicles everywhere. And having gone through it once, I'm no longer fooled by what *looks* "flat" at 500, or even 50 feet. Barry: I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. I agree. And it could be a place to go. I was just saying that a mall/strip center parking lot isn't necessarily the "ah...I'll go there!" place. Even at 7 a.m., there can be cars and people everywhere. |
#10
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B A R R Y schrieb:
I'd rather hit a bus shelter or light poles @ 40-50 MPH than go in inverted after a stall/spin @ 200-300 AGL. But I hope that you rather risk a stall/spin than to hit a crowd of pedestrians with that meat chopper turning. |
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