Emergency Descents

Gilbert Buettner said:
Many years ago, a DPE told me he wants to see the applicant IMMEDIATELY pitch down 20 degrees and enter a left 45-degree spiraling descent ...
Click to expand...
Clip4 said:
... Use bank angle between 30° and 45° to maintain positive load factors during the descent.
...
Click to expand...
With in-flight fire, when you've pulled mixture all the way back and shut off the fuel, you need to get to the ground ASAP. Practicing this in my 172N with a CFI, we found the fastest descent was no flaps, bank at 60* and pitch for airspeed as fast as possible given conditions. Just below Vne in calm air, otherwise slower.

Less bank angle is easier to control but doesn't descend as quickly. Normally, bank angles more than 45* are reserved for commercial maneuvers. You need to make a controlled descent, so 30* and 45* are not wrong, but the point is to use the greatest bank angle you can confidently control.
 
What I was taught for emergency procedures is that you should at least know your initial steps by memory and act, then reference the checklist to make sure you didn’t miss anything. Usually a CFI will know the DPE’s preference, this is an area where different people have different approaches sometimes.


Real world in a typical single engine piston you should have it memorized IMO, there aren’t that many steps.
 
MauleSkinner said:
The theory is you can speed up to lean the mixture enough so it can’t burn. I don’t know of examples where it’s worked, but if you stop seeing flames coming from under the cowling as you increase speed, it probably did.
Click to expand...
Gilbert Buettner said:
Many years ago, a DPE told me he wants to see the applicant IMMEDIATELY pitch down 20 degrees and enter a left 45-degree spiraling descent. Our local DPE here says if there is a good place to land in front of you, put the flaps down all the way and push the nose down (even though the ACS says the applicant should initiate a bank).

For the checkride, I would follow the ACS. Don't waste time on the checklist first if you are on fire.
Click to expand...
This is what the FAA says:

An emergency descent is a maneuver for descending as rapidly as possible to a lower altitude or to the ground for an emergency landing. The need for this maneuver may result from an uncontrollable fire, a sudden loss of cabin pressurization, or any other situation demanding an immediate and rapid descent. The objective is to descend the airplane as soon and as rapidly as possible, within the structural limitations of the airplane.
Simulated emergency descents should be made in a turn to check for other air traffic below and to look around for a possible emergency landing area. A radio call announcing descent intentions may be appropriate to alert other aircraft in the area. When initiating the descent, a bank of approximately 30 to 45° should be established to maintain positive load factors (“G” forces) on the airplane.
Emergency descent training should be performed as recommended by the manufacturer, including the configuration and airspeeds. Except when prohibited by the manufacturer, the power should be reduced to idle, and the propeller control (if equipped) should be placed in the low pitch (or high revolutions per minute (r.p.m.)) position. This will allow the propeller to act as an aerodynamic brake to help prevent an excessive airspeed buildup during the descent. The landing gear and flaps should be extended as recommended by the manufacturer. This will provide maximum drag so that the descent can be made as rapidly as possible, without excessive airspeed. The pilot should not allow the airplane’s airspeed to pass the never-exceed speed (VNE), the maximum landing gear extended speed (VLE), or the maximum flap extended speed (VFE), as applicable.
In the case of an engine fire, a high airspeed descent could blow out the fire. However, the weakening of the airplane structure is a major concern and descent at low airspeed would place less stress on the airplane. If the descent is conducted in turbulent conditions, the pilot must also comply with the design maneuvering speed (VA) limitations. The descent should be made at the maximum allowable airspeed consistent with the procedure used. This will provide increased drag and therefore the loss of altitude as quickly as possible. The recovery from an emergency descent should be initiated at a high enough altitude to ensure a safe recovery back to level flight or a precautionary landing. When the descent is established and stabilized during training and practice, the descent should be terminated.

An immediate nose down pitch of 20 degrees will preclude flaps and gear in a lot of planes because you exceed VFE and VLE.
 
Clip4 said:
This is what the FAA says:

An emergency descent is a maneuver for descending as rapidly as possible to a lower altitude or to the ground for an emergency landing
...
The landing gear and flaps should be extended as recommended by the manufacturer. This will provide maximum drag so that the descent can be made as rapidly as possible, without excessive airspeed. The pilot should not allow the airplane’s airspeed to pass the never-exceed speed (VNE), the maximum landing gear extended speed (VLE), or the maximum flap extended speed (VFE), as applicable.
In the case of an engine fire, a high airspeed descent could blow out the fire. However, the weakening of the airplane structure is a major concern and descent at low airspeed would place less stress on the airplane.
...
An immediate nose down pitch of 20 degrees will preclude flaps and gear in a lot of planes because you exceed VFE and VLE.
Click to expand...
This is a common debate: whether to maximize drag (max flaps, gear down, full slip, etc.) with slow airspeed, or fly it clean at a steep bank angle at high speed. IME, with my airplane, clean at a steep bank at high speed gets you down significantly faster. And the POH says the high airspeed is preferred as it may put out the fire.
However, the FAA makes a valid point about airframe structural integrity and turbulence. If you suspect that is a factor, descending slow and dirty even if it takes longer may be a better tradeoff.
 
MRC01 said:
This is a common debate: whether to maximize drag (max flaps, gear down, full slip, etc.) with slow airspeed, or fly it clean at a steep bank angle at high speed. IME, with my airplane, clean at a steep bank at high speed gets you down significantly faster. And the POH says the high airspeed is preferred as it may put out the fire.
However, the FAA makes a valid point about airframe structural integrity and turbulence. If you suspect that is a factor, descending slow and dirty even if it takes longer may be a better tradeoff.
Click to expand...
This really shouldn’t even be a debate. Maximum speed for configuration will give you the steepest descent for that configuration, and that’s the primary goal. But if you suspect structural damage or excessive turbulence, you need to adjust appropriately.
 
mandm said:
Has anyone experienced an in-flight fire?
Click to expand...

In flight electrical fire/smoke/fumes about 10nm out from landing. Made a call on Unicom, then killed the avionics master. Things did not improve, so I killed the master switch.

There I was, fat, dumb and scared on short final. And the afternoon bird launch occurred. Then there were a ton of hogs running across the runway, go around. Planted that plane on the numbers, rolled to the exit, pulled the mixture and unassed the plane.
 
Just my two cents, but I think we are confusing the ACS maneuver "Emergency Descent" with the POH "In-Flight Fire". These are two different things. Now while an inflight fire will likely lead to an emergency descent, the ACS says nothing about fire. The ACS maneuver is about getting down quickly and in a controlled manner. Most non pressurized single engine pistons probably don't have a stand-alone Emergency Descent procedure.
 
MauleSkinner said:
This really shouldn’t even be a debate. Maximum speed for configuration will give you the steepest descent for that configuration, and that’s the primary goal. But if you suspect structural damage or excessive turbulence, you need to adjust appropriately.
Click to expand...
Ay, there's the rub - key phrase: relative to the configuration.
When dirty, pitching for maximum allowable speed gives you the fastest descent for that configuration (e.g. when dirty).
When clean, the same is true - it gives the fastest descent when clean.

But the fastest descent when clean, may be faster than the fastest descent when dirty. At least in my plane it is, according to flight tests I have done with a CFI. Perhaps in other planes it is the reverse.

Either way the point is that the two configurations don't necessarily give the same descent rate, so know which gives faster descent in your airplane.
 
MRC01 said:
I'll add that every pilot should be able to do a controlled descent at least 45* bank. If not, his skills have deteriorated below PTS and he needs to practice more.
Click to expand...
I agree. One school I go to talks about students not being able to do an instrument approach without the autopilot. Then they want them to do a steep spiral in IMC for an emergency decent. It sounds like a bad idea to me. I think they should teach a descending 90 degree turn then continue to go down. Steep spiral in IMC sounds like a good chance spatial disorientation could happen to them.
 
MRC01 said:
But the fastest descent when clean, may be faster than the fastest descent when dirty. At least in my plane it is, according to flight tests I have done with a CFI.
Click to expand...

One question I've always had when comparing the two is this - if you are at maximum airspeed while DIRTY, then in many training airplanes once you level off at the bottom of the emergency descent you're basically at landing speed already, and can land pretty much right where you are - in other words, you could almost take the emergency descent all the way to the ground.

But if you're doing the emergency descent clean, then once you get down to the bottom, you now have to lose a lot of speed, which takes time, of course, and means you have to refigure where you're landing.

So the maximum descent rate achieved isn't really the whole story, the total time from initiation to actually touching down is what's important. It would be interesting to see a test where each scenario is timed all the way to landing.

As mentioned, I used to teach a lot in a Seminole. We'd do the emergency "half-dirty", meaning gear down but not flaps due to the speed range for each. At 130-140 kias in the descent at a 45 degree or so bank, we came down really fast - but once we rolled back to a level attitude, speed dropped off really quickly. I mean, once the wings were level we were under the flap speed, could throw in full flaps immediately and then pretty much land right away.
 
MRC01 said:
Ay, there's the rub - key phrase: relative to the configuration.
When dirty, pitching for maximum allowable speed gives you the fastest descent for that configuration (e.g. when dirty).
When clean, the same is true - it gives the fastest descent when clean.

But the fastest descent when clean, may be faster than the fastest descent when dirty. At least in my plane it is, according to flight tests I have done with a CFI. Perhaps in other planes it is the reverse.

Either way the point is that the two configurations don't necessarily give the same descent rate, so know which gives faster descent in your airplane.
Click to expand...
But again, there should be no debate. Figure out what’s the fastest for the airplane, and use that unless conditions dictate otherwise.
 
MauleSkinner said:
But again, there should be no debate. Figure out what’s the fastest for the airplane, and use that unless conditions dictate otherwise.
Click to expand...
For a particular airplane, sure.
Better yet, not only know which is fastest, but also how much worse the other is, because that will guide which to use depending on conditions.
Yet there are thousands of different airplanes, and many people oversimplify, thinking one or the other must always be best in every case, so the debate rages on...
 
MRC01 said:
For a particular airplane, sure.
Click to expand...
you should fly the airplane you’re in, not something else.
MRC01 said:
Better yet, not only know which is fastest, but also how much worse the other is, because that will guide which to use depending on conditions.
Click to expand...
so if conditions don’t allow a clean redline descent, and the other options are too slow, you just give up? Who cares what the difference is?
MRC01 said:
Yet there are thousands of different airplanes, and many people oversimplify, thinking one or the other must always be best in every case, so the debate rages on...
Click to expand...
Again, fly the airplane you’re in. It’s that simple.
 
MauleSkinner said:
... so if conditions don’t allow a clean redline descent, and the other options are too slow, you just give up? Who cares what the difference is?
...
Click to expand...
You're missing my point, so here's an example: suppose your airplane's clean descent is more than twice as fast (say, 5000 fpm versus 2000 fpm). It gets you down so much faster you'll be more likely to use it despite risks from turbulence or being at such a high speed you must slow down before you can land. If, OTOH, your clean descent is only a little faster than dirty (say, 4000 fpm vs 3000 fpm) then you will be more likely to go dirty since it's slower and more compatible with turbulence and landing.

My point is to not only know which is faster, but also how much faster, because that affects your decision making to optimize the outcome given conditions.
 
MRC01 said:
You're missing my point, so here's an example: suppose your airplane's clean descent is more than twice as fast (say, 5000 fpm versus 2000 fpm). It gets you down so much faster you'll be more likely to use it despite risks from turbulence or being at such a high speed you must slow down before you can land. If, OTOH, your clean descent is only a little faster than dirty (say, 4000 fpm vs 3000 fpm) then you will be more likely to go dirty since it's slower and more compatible with turbulence and landing.

My point is to not only know which is faster, but also how much faster, because that affects your decision making to optimize the outcome given conditions.
Click to expand...
Im getting your point. My point is if I’m doing an emergency descent, getting down fast is the objective. I’ll take the fastest way down. If the fastest way down is unusable for some reason, I’ll take the alternative, knowing that it may result in death, but there’s not a lot of choice.

i never completed statistics in college, so I’m not going to do math to figure out which procedure to used based on my calculations of time remaining to live.
 
MauleSkinner said:
Im getting your point. My point is if I’m doing an emergency descent, getting down fast is the objective. I’ll take the fastest way down. If the fastest way down is unusable for some reason, I’ll take the alternative, knowing that it may result in death, but there’s not a lot of choice.

i never completed statistics in college, so I’m not going to do math to figure out which procedure to used based on my calculations of time remaining to live.
Click to expand...
It doesn't require statistics or math to think, "My clean descent is a lot faster than dirty, so it's my go-to unless circumstances dictate strongly otherwise", or to think "My clean descent is only slightly faster than dirty, so I'll always go dirty unless I'm above 5000' in calm air".

It's an instant decision based on simple rules of thumb. But one's particular rules of thumb will vary depending on the difference.
 
MRC01 said:
It doesn't require statistics or math to think, "My clean descent is a lot faster than dirty, so it's my go-to unless circumstances dictate strongly otherwise", or to think "My clean descent is only slightly faster than dirty, so I'll always go dirty unless I'm above 5000' in calm air".

It's an instant decision based on simple rules of thumb. But one's particular rules of thumb will vary depending on the difference.
Click to expand...
if a situation requires an emergency descent, i don’t see any reason to do “sort of” an emergency descent as a default.
 
MauleSkinner said:
if a situation requires an emergency descent, i don’t see any reason to do “sort of” an emergency descent as a default.
Click to expand...
Straw man argument. Nobody is saying take the second best "sort of" emergency descent. The fact is that even if the clean configuration is faster, it might not be possible given the conditions. Last thing you want to do is always go clean simply because it's the fastest way down, then lose control during the descent because you were going too fast for the turbulence. Or always go dirty because you can do it regardless of conditions, then die of fire or smoke in flight because you didn't get down fast enough.
 
MRC01 said:
Nobody is saying take the second best "sort of" emergency descent. The fact is that even if the clean configuration is faster, it might not be possible given the conditions. Last thing you want to do is always go clean simply because it's the fastest way down, then lose control during the descent because you were going too fast for the turbulence. Or always go dirty because you can do it regardless of conditions, then die of fire or smoke in flight because you didn't get down fast enough.
Click to expand...
Exactly what you’ve been arguing against.
 
No, and if you think that, you did miss my point.
To clarify, I'll quote myself from above:
MRC01 said:
...
However, the FAA makes a valid point about airframe structural integrity and turbulence. If you suspect that is a factor, descending slow and dirty even if it takes longer may be a better tradeoff.
Click to expand...

Actually as I read your above comment again, it sounds like we agree.
MauleSkinner said:
... I’m doing an emergency descent, getting down fast is the objective. I’ll take the fastest way down. If the fastest way down is unusable for some reason, I’ll take the alternative, knowing that it may result in death, but there’s not a lot of choice.
...
Click to expand...
 
Most excellent discussion all, thank you for sharing. Needless to say I did ask two CFI's at my school for their opinion and both gave me the same answer- for an "engine fire" situation begin your emergency decent (bank for 30-45 and pitch for 100KTS) and during that spiral, from memory run the checklist for engine fire. Did this on the check ride and DPE approved. it's what he was looking for. Yay.

thanks!
 
DelayedFlight said:
Most excellent discussion all, thank you for sharing. Needless to say I did ask two CFI's at my school for their opinion and both gave me the same answer- for an "engine fire" situation begin your emergency decent (bank for 30-45 and pitch for 100KTS) and during that spiral, from memory run the checklist for engine fire. Did this on the check ride and DPE approved. it's what he was looking for. Yay.

thanks!
Click to expand...
All emergency descents are for fires?. Just out of interest, what are you going to do if the examiner simply says show me an emergency descent?
 
Last edited:
RussR said:
All? Come on now, you know that's not true.

"Most in training", yes. "Vast majority on private pilot checkrides", yes. But not "all", not even in training (let alone real flying).
Click to expand...
Missed the ? Fixed it.
 
Instead of STOL drags, we should do it vertically - have emergency descent drags.

Start at 6k, first one to 3k without parts fluttering to earth wins.

Better yet, do it over an airport with parallel runways, each competitor gets their own. First one to land, stop, and get out wins (mags off).
 
You must log in or register to reply here.
Back
Top