Emergency descent question

N801BH said:
It is the pull up at the bottom of the decent that sheds the wings.:yes::hairraise:
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Right. There's no reason to pull all those Gs to slow down at the top of the descent. Give yourself a few more minutes of life. :eek:
 
denverpilot said:
How many old fart, 50+, out of shape pilots you think are going to be fine going straight to 4.4G with no experience doing so?
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Everyone has different abilities and pilots are still responsible for flying within their own.
 
wabower said:
Depends how you do it, and whether you want to be sure you get on the ground rather than into it.
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Also depends on the fire, if my hair is singeing and I'm still at 9000', I really don't care if I go into the ground. Fire and I are well acquainted, I'll take nearly any other death.
 
With all of this being said. What is the DPE going to be looking for? For example if he says your one of your passengers is experiencing signs of hypoxia. If I decided to use a forward slip to get down, would that not be fine? What if I decided to just pull the power and nose down at Vno? The Piper Sport I am flying does not have a published Emergency Descent Procedure. It is not on the checklist either.


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MDeitch1976 said:
With all of this being said. What is the DPE going to be looking for? For example if he says your one of your passengers is experiencing signs of hypoxia. If I decided to use a forward slip to get down, would that not be fine? What if I decided to just pull the power and nose down at Vno? The Piper Sport I am flying does not have a published Emergency Descent Procedure. It is not on the checklist either.


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Probably the steep power off spiral.
 
Matt, a good friend of mine flies a piper sport and has a lot of experience as a pilot through the years. He also posts on this board occasionally, really more lurks :-)
Anyway, shall I put you in touch with him?
 
Jeanie said:
Matt, a good friend of mine flies a piper sport and has a lot of experience as a pilot through the years. He also posts on this board occasionally, really more lurks :-)
Anyway, shall I put you in touch with him?
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Yes, please.


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John Collins said:
The deck angle is wild. Pilot's are generally unwilling to pitch the nose low enough to obtain the desired speed when demonstrating the maneuver and have to be encouraged to lower the nose further.
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That it is. It always takes me some poking at a student to get them to lower the nose far enough.
 
RoscoeT said:
50% more induced drag is insignificant? And there is nothing wrong with putting the max Gs on an airplane. They are designed for it. And it will not break or cause problems if you go slightly over. There is a 50% margin before airframe deformation occurs. Not saying that you should ignore the g-limits, but going slightly over one time in an emergency won't hurt anything. You just don't want to do it continually. But pulling to the max g-load either 4.4 or 3.8 is not a problem. The designers allow for that to be done on every flight. And .5G isn't going to make any difference unless you're near the ultimate load failure point (6.6G in a utility category spamcan).
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There's no 50% margin for permanent deformation, that number applies to the excessive load the structures are supposed to tolerate before catastrophically failing. Of course the vast majority of GA planes flying today were designed before computerized structural analysis made it possible to predict stress induced failures accurately. Prior to that the engineers themselves generally added "safety margins" above and beyond what the FAA required so there is a good chance your typical Piper or Cessna single will indeed come through unbent if you briefly increase the load slightly beyond the published limit. Then again there's a good (or is that bad?) chance that a 40+ year old aluminum airplane might be a bit weaker than when it left the factory. Now maybe if the plane's on fire an unbent wing might be a lower priority than getting on the ground ASAP.

In any case few pilots are capable of sensing let alone maintaining a constant 3.8 or 4.4 g load in a steeply banked turn and especially in an emergency.
 
I "grayed out" at 4 gs, and that was when I was young. I've always known that the airplane would take more than me.
 
As you are asking this for the PPL, guessing this isnt a turbine question.


In a piston plane here is what I do.

Constant speed, fixed gear:

Prop to 21, Man to 16 (depending on plane), cowl flaps up, leave the mixture leaned to whatever alt you were at EGT, pitch for just below vne and pull the power as you go down to maintain target manifold, richen the mixture to keep your target EGT, if CHTs start dropping too fast add a little manifold.

In a 206/7 this will give you about a 4000FPM decent.

For a basic trainer, same thing bring the power back to the bottom of the green, maintain EGT with the mixture and pitch for just under vne, add some power if the CHTs start dropping off too fast, watch your rpm.

I normally dont use flaps, there are some turbines that can be dropped with the prop full forward and some flaps and get a better decent under vfe, but thats turbine.
 
RoscoeT said:
Disagree. As has already been mentioned, it depends on your altitude above your landing site. If you're at pattern altitude, then I'd use your method. If higher, your method will give far from the fastest vertical descent rate.

Regarding bleeding off excess speed, a 4.4G power-off steep turn will get you from Vne to 1.3Vso in literally a few seconds. If you're much higher than pattern altitude, a Vne power-off max G banked turn will get you down a whole lot faster than the way you describe. Even with the few seconds you spend bleeding speed, you'll still come out far ahead. Again, if you're already very low, then you might as well fly nearly a normal slipped approach.
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Guess I forgot to mention power off ;) my bad.
 
Doggtyred said:
Guess I forgot to mention power off ;) my bad.
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I assumed power off, but even in a full power-off slip with flaps, Cessnas don't come down that fast. They've gotta be the worst slipping airplanes ever built.
 
RoscoeT said:
I assumed power off, but even in a full power-off slip with flaps, Cessnas don't come down that fast. They've gotta be the worst slipping airplanes ever built.
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Falling leaf is about the fastest way I found to bring down a 152 and is effective in a 172 as well. It would be my preferred descent with an engine fire as it will pull the flames out of the front of the cowl protecting the passenger compartment on singles and spars on twins.
 
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Henning said:
Falling leaf is about the fastest way I found to bring down a 152 and is effective in a 152 as well.
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Yep, that would work a lot better than a slip. 150's spin real nice. I bet an accelerated spin would work best...as far as benign descent techniques go. There's also the knife-edge falling leaf, but I think you'd have airspeed problems during that one...fastest way down short of pulling off both wings though. :)
 
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RoscoeT said:
Yep, that would work a lot better than a slip. 150's spin real nice. I bet an accelerated spin would work best of all. :)
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When I started fly I used to fly with this old UFO, he did his ride in 27 IIRC. He told me his checkride started with him taking the plane, a Jenny, up solo and doing a 2 turn spin to a heading. Surviving that he was to come back and pick up the examiner. In those days spinning was what you did to minimize risk and result of CFIT when having to descend through IMC. This was Pre Sperry and Doolittle.
 
Henning said:
He told me his checkride started with him taking the plane, a Jenny, up solo and doing a 2 turn spin to a heading. Surviving that he was to come back and pick up the examiner.
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Guess they didn't have much faith in spin recovery technique back then. :)
 
If you were going to forward slip for a descent, which would be better no flaps and higher speed, or flaps and within Vfe?


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MDeitch1976 said:
If you were going to forward slip for a descent, which would be better no flaps and higher speed, or flaps and within Vfe?


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Flaps up 4.4G slipping turn at Vne. :)
 
RoscoeT said:
Flaps up 4.4G slipping turn at Vne. :)
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My instructor did not teach me this method. When she first asked me what I thought I should do, I initiated a forward slip no flaps. Her thoughts were this is adequate because you are getting down at a faster than normal rate to an altitude that you can then make a proper landing.

I will bring an instructor along when I try out this other method. Also, the Piper Sport has a load factor up to 4G.


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MDeitch1976 said:
My instructor did not teach me this method. When she first asked me what I thought I should do, I initiated a forward slip no flaps. Her thoughts were this is adequate because you are getting down at a faster than normal rate to an altitude that you can then make a proper landing.

I will bring an instructor along when I try out this other method. Also, the Piper Sport has a load factor up to 4G.


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The slip at Vne part was a joke. If you've never done the high speed banked descent, get with an instructor and be conservative if you don't have a g-meter.
 
RoscoeT said:
The slip at Vne part was a joke. If you've never done the high speed banked descent, get with an instructor and be conservative if you don't have a g-meter.
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Yeah, definitely have never done it. I will bring an instructor that wants to have a little fun.
 
RESURRECTION!

denverpilot said:
Depends on the specific airplane.

How much faster in seconds will you be on the ground pulling 4.4 vs 3 or so? I suspect it's not a significant difference.

None of the new Cessnas have been Utility certified for over a decade now, as one significant example.
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I wouldn't go that far! My 98' C172S is certified in Normal and Utility Category

John Collins said:
I instruct in Bonanzas. The emergency descent procedure varies by specific model. Earlier models have lower flap and gear speeds. For later models, the flaps have an approach detent setting, while the earlier aircraft have continuous position flaps without any detent other than up or down. For my particular model, a 68 V35A, the flaps are not used in the emergency descent as there is no approach detent. Power is set to idle, gear lowered, prop full forward, pitch for descent at 145 KIAS (Maximum gear extended speed). The deck angle is wild. Pilot's are generally unwilling to pitch the nose low enough to obtain the desired speed when demonstrating the maneuver and have to be encouraged to lower the nose further. I have a cue that I use that tells me when I am at the right deck angle, the seat rocks forward on the rails when I am at the desired deck angle as the CG of the pilot goes over center. Rate of descent is close to 6000 FPM, so from 6000 AGL, I can be in the flare one minute later.
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I'd love to experience this someday.

NineThreeKilo said:
As you are asking this for the PPL, guessing this isnt a turbine question.


In a piston plane here is what I do.

Constant speed, fixed gear:

Prop to 21, Man to 16 (depending on plane), cowl flaps up, leave the mixture leaned to whatever alt you were at EGT, pitch for just below vne and pull the power as you go down to maintain target manifold, richen the mixture to keep your target EGT, if CHTs start dropping too fast add a little manifold.

In a 206/7 this will give you about a 4000FPM decent.

For a basic trainer, same thing bring the power back to the bottom of the green, maintain EGT with the mixture and pitch for just under vne, add some power if the CHTs start dropping off too fast, watch your rpm.

I normally dont use flaps, there are some turbines that can be dropped with the prop full forward and some flaps and get a better decent under vfe, but thats turbine.
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Why are we so concerned with engine management technique? Remember this is an EMERGENCY descent.

Henning said:
Also depends on the fire, if my hair is singeing and I'm still at 9000', I really don't care if I go into the ground. Fire and I are well acquainted, I'll take nearly any other death.
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Not sure what you meant here....Fire or Earth?

Captain said:
When you get to bigger airplanes you find there are two types of emergency descent too. High Speed and Low Speed. Think structural failure for low speed and lost cabin pressure for the high speed.

There was a BA flight where the captains window blew out sucking the Captain halfway out of the plane. Explosive decompression and the FO elected to do a high speed Emergency Descent. Poor choice IMO. With the structural Damage and a Human hanging out if the plane Low Speed would have been my choice.

I would imagine the choice between dirtying up and flying Vfe or staying clean and flying Vne has to do with how close Vfe is to Vne. If it a 200 kt split and the plane has spoilers then Vne may be the best descent choice. If there's no split or it's only 30 kts or so then getting all that extra drag may help get a better descent rate.

It's all about the descent rate and starting altitude doesn't really matter as slowing to Vref with no power takes no time...or at least inconsequential amount of time compared to getting down (the point of the ED).

I think the POHs aim to maximize the descent rate in selecting configuration.
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Have a link for the NTSB report? I'd like to read that one
 
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