Emergency Descent

Tantalum said:
Wasn't that taught a long time ago as a way to get out of inadvertent IMC.. I'm talking Sopwith Camel days?
Click to expand...

Luftwaffe for sure, during WWII.

Bob
 
My plane doesn't have a POH, and neither page in my Owners Manual addresses emergency descents. With engine fire, push and accelerate to Vne to try to blow it out. When extinguished, or if not burning, my plane falls out of the sky at >2500 fpm at cruise speed, idle throttle and 45° bank. That is well above both flap and gear speed.
 
Mine hasn’t one either, and like I said if something is on fire Vne becomes a nice number in a book. Mooney’s are built stout, I know pilots who’ve pushed them well beyond Vne and not only lived to tell the tail but had flyable aircraft afterwards.

Absent an emergency I’ll never let my ship get that fast. If I’m on fire I’ll blow right through it. The fire is way more likely to tear the wings off than the air.
 
An ED at Vne is probably pretty dangerous to be training students, especially if you're playing around at 3000 AGL or so. The ground comes up fast and you're still at Vne. I can completely understand why a DPE doing a PPL ride would prefer the dirty descent. It's the method I'll use. Gives me an extra 20 or 30 seconds to get into a good landing configuration too and confirm obstacles and what not.
 
ScottinIowa said:
And that's what makes sense to me too, but others and the AFH seem to suggest flaps is the best method. Seems odd to me. I'm going to bring this up with my DPE and see what he prefers.
Click to expand...

It all depends on how far up the Vne is in relation to Vfe. In most basic singles they are so close that the top of the white arc is the best option. But in faster airplanes, like a Cirrus, top of the yellow arc is. {Update: Steingar made that point above.}

Look at the problem from the energy perspective. You have the potential energy at the altitude, which you must transfer away safely. So, you must find a way that affords the most drag. At the Vfe it's the drags from the flaps, and at Vne it's the parasitic drag. Whichever one wins is the answer for your airplane (unless you have spoilers etc.).

Obviously in both cases you can dump more energy per second by increasing the AoA, which is where the spiral comes in. By spiraling you increase the effective weight of the airplane and dump the energy faster. It works great. If you can do a barrel roll all the way down, it's even better. The biggest downside of a spiral is how you can easily overstress the airplane and fold a wing. Otherwise it's the best way, because science.

There's also a special, stupid way, which offers a solution that is similar in performance to the barrel roll: stall it all they way to the ground. It's attractive, because it does not require you to pull Gs. Unfortunately, it requires an even more exquisite level of control: you should not enter the falling leaf mode, you must not spin it in, etc. Because the whole planform of the airplane faces the oncoming air at a very high AoA, it creates a very good drag. But don't do it. Too high a risk of not pulling out in time for the landing.

P.S. I'm against using a spin, because it's too unpredictable. A recovery may take much longer than anticipated, especially when established. Spin can become flat suddenly. Overall, the risk is not worth it. I once read memoirs (of A. Kvochur) where he was spinning Yak-52. It was a championship level airplane at the time of introduction. So, one day he spun it once, spun it twice, then whooh - recovery was ineffective suddenly. He had to wait a few extra rotations before the airplane popped out of the spin. If he tried to pump the elevator, it would've made it worse. So he had no choice but sit tight and wait. Imagine doing that when you're on fire _and_ you timed your spin recovery just in time to make a landing. Secondary to this, you're going to exit the spin at a random heading.
 
Last edited:
steingar said:
In your airplane maybe. An old saw among Mooney pilots. A Mooney will go down or slow down, but not at the same time.
Click to expand...
Even a Mooney will slow nicely with power off entering a 45 degree bank.
 
Clip4 said:
Even a Mooney will slow nicely with power off entering a 45 degree bank.
Click to expand...

Why slow down? Idle throttle, bank 45°, lkwer the nose to maintain cruise IAS.

For someone above, Vfe =125 mph; Vg = 120 mph; top of yellow = 175 mph; Vne = 200 mph. I ain't slowing from cruise (typically 145 mphi), I'm lowering the nose and banking once the fire is out. I've practiced with a CFI, it works really well.
 
Tantalum said:
Wasn't that taught a long time ago as a way to get out of inadvertent IMC.. I'm talking Sopwith Camel days?
Click to expand...
Even into WWII...I used to know a B-17 guy who said at the beginning of the war, many (or most, I can't remember which) weren't instrument qualified, so that was the approved procedure.
 
So, I went up in the 140 today and practiced the dirty descent. I liked it actually. I was Vfe almost immediately after hitting the 30 degree bank. I started at 3000 AGL and dropped 1000 FPM easily. I can definitely see a place for the clean descent if you're higher, but for closer to the ground I think the dirty is perfect. It was really easy to level off and get into a landing configuration.
 
ScottinIowa said:
You could also argue that during a check ride if you're doing maneuvers at 3000AGL or less, you wouldn't want to hurl towards the ground at the top of the green arc. Flaps might be the better option assuming you'll be putting it down in a field within a couple minutes.
Click to expand...

My checkride was awhile back (2007). DPE was a check airmen for SWA also (real sharp). He basically said," don't try picking the fly turds out of the pepper" ... was just looking for a reasonable response. Told him I'd be 45* bank flaps out at top of the white arc, unless on fire ... he said "good" and went on to the next task.
 
Here mine.

Fixed gear, cowl flaps closed, prop forward, throttle bottom of the green, mixture to keep CHTs, pitch for just shy of VNE.

RG, same as above, but slowing to VLO, gear down, pitch for VLE, that works well for most planes that can redline or near redline with the gear out. If you have a much lower VLE than you’d have to experiment with your rate, probably have to use GPS as most VSIs will max out well before.

Not a fan of loading the plane up or the reduced visibility of doing banks

ScottinIowa said:
An ED at Vne is probably pretty dangerous to be training students, especially if you're playing around at 3000 AGL or so. The ground comes up fast and you're still at Vne. I can completely understand why a DPE doing a PPL ride would prefer the dirty descent. It's the method I'll use. Gives me an extra 20 or 30 seconds to get into a good landing configuration too and confirm obstacles and what not.
Click to expand...

If pitching 10kts or so below VNE is outside of the students capabilities I’d say the student can’t preform the maneuver and requires further training.
 
steingar said:
Depends on the airplane. In the Cherokee 140 I used to fly the procedure was just like that other fellow said: power off, flaps in, biggest slip I could manage and down she came. I lost 7K feet on downwind once, no foolin'. But the Cherokee's flap speed and cruise speed weren't terribly different, so it made good sense.

The Mooney I now fly cruises at 160 mph but has a flap speed of about 100. Slowing to flap speed would be nearly nonsensical, if there really is a fire I'll burn up before I hit it. Gear speed is 120, again it will take some doing so slow down to that. Says me point the nose down and get down right now. If the excrement really has hit the air conditioning, I'm not going to be too picky about any of those V speeds either.

Personally, I think the DPE will be more impressed with knowing why we do what we do than with rote memorization of a procedure.
Click to expand...

If you are "not too picky about any of those V speeds", why would you wait until 120 to throw out the gear?
 
GRG55 said:
If you are "not too picky about any of those V speeds", why would you wait until 120 to throw out the gear?
Click to expand...
Yes, I could probably slow down the airplane to 120 and drop the gear with the Johnson bar. But we’re talking emergency here. If the emergency is Mrs. Steingar ain’t feelin’ so hot, yeah, slow down to 120, drop gear, slow to 100, drop flaps, and down she comes in a slip. If the emergency involves a fire the nose gets pointed down and we boogie. The fast descent could put it out. And like I said, forget V speeds. Thing is, Mooney’s are built stout. I’ve talked to more than 1 Mooney pilot who’ve inadvertently got past Vne. Mooney’s don’t shed parts so easily, unlike some other aircraft.
 
steingar said:
Yes, I could probably slow down the airplane to 120 and drop the gear with the Johnson bar. But we’re talking emergency here. If the emergency is Mrs. Steingar ain’t feelin’ so hot, yeah, slow down to 120, drop gear, slow to 100, drop flaps, and down she comes in a slip. If the emergency involves a fire the nose gets pointed down and we boogie. The fast descent could put it out. And like I said, forget V speeds. Thing is, Mooney’s are built stout. I’ve talked to more than 1 Mooney pilot who’ve inadvertently got past Vne. Mooney’s don’t shed parts so easily, unlike some other aircraft.
Click to expand...

I agree, you could do that more confidently in a Mooney than in some other airframes. And with the Vne of a high performance single you're probably correct the fastest way down to terra firma is to point it down. But I also think you could safely hang the gear and flaps out on the Mooney at speeds above 120 and 100, respectively, if you really needed to.
 
GRG55 said:
I agree, you could do that more confidently in a Mooney than in some other airframes. And with the Vne of a high performance single you're probably correct the fastest way down to terra firma is to point it down. But I also think you could safely hang the gear and flaps out on the Mooney at speeds above 120 and 100, respectively, if you really needed to.
Click to expand...
Good point. Once the airplane is on fire it belongs to the insurance company. If I prang the gear on the insurance company’s airplane you can cry me a river. I think the insurance company would rather I survived so I could keep paying my premiums.
 
="steingar, post: 2549544, member: 1960it belongs to the insurance company. If I prang the gear on the insurance company’s airplane you can cry me a river...
Click to expand...

What a bad thought process that got spread around.

The better condition the box is chances are the better condition the contents will be in.
 
Last edited:
James331 said:
What a bad thought process that got spread around.
The better condition the box is chances are the better condition the contents will be in.
Click to expand...
Considering how An-26 augered it in in Syria a few months ago when a flap flew off on final, I agree, but it's a balance of the risk of a flap departing versus the risk of burning up before landing.
 
zaitcev said:
Considering how An-26 augered it in in Syria a few months ago when a flap flew off on final, I agree, but it's a balance of the risk of a flap departing versus the risk of burning up before landing.
Click to expand...

Ether way the less damaged the aircraft often the less dead the pax
 
You must log in or register to reply here.
Back
Top