Steep Spiral Descent

[ArnoldPalmer]

Working on my commercial - and I have a new nemesis. The steep spiraling descent as part of emergency maneuvers during a simulated engine fire.

A question for the CFIs - what speeds and angles do you teach this maneuver at? My current CFI has me do 65 kts KIAS and almost to a 60 degree bank - this in a 172. I see some YouTube videos where the speeds are closer to 100 and bank almost to 50 -- with a good descent rate of 2K FPM.

Thanks

Edit: to add type of a/c.

 

[Cap'n Jack]

Which airplane? That will make a difference for the speeds and other parts of the procedure.

I remember, in a C-152, full flaps, 45°bank, 85 knots (Vfe).

 

[luvflyin]

Working on my commercial - and I have a new nemesis. The steep spiraling descent as part of emergency maneuvers during a simulated engine fire.

A question for the CFIs - what speeds and angles do you teach this maneuver at? My current CFI has me do 65 kts KIAS and almost to a 60 degree bank - this in a 172. I see some YouTube videos where the speeds are closer to 100 and bank almost to 50 -- with a good descent rate of 2K FPM.

Thanks

Edit: to add type of a/c.

I ain't a CFI but I'm gonna stick my nose in anyway. Seeing as how the reason for the emergency descent is fire, maybe the faster airspeed methods might be good. As I recall the POH says something about trying to 'blow' it out, in so many words.

 

[OkieAviator]

Emergency descent can be more than just fire. Engine fire you’re right, basically cut off mixture, pitch down and haul ass until it’s out. Potential hypoxia, or loss of cabin pressure or something like that you reduce power and nose down staying below Vne. Engine out you may do a spiral staying above the field, that’s your glide speed adjusting as needed to hit the field.

Short of a slip I’m not sure why you would need to bank more than 45. An emergency descent is still a controlled descent. Keep it comfortable and out of the red...

 

[dmspilot]

I ain't a CFI but I'm gonna stick my nose in anyway. Seeing as how the reason for the emergency descent is fire, maybe the faster airspeed methods might be good. As I recall the POH says something about trying to 'blow' it out, in so many words.

Steep spiral and emergency descent are two completely different maneuvers.

 

[ArnoldPalmer]

Which airplane? That will make a difference for the speeds and other parts of the procedure.

I remember, in a C-152, full flaps, 45°bank, 85 knots (Vfe).

Cessna 172.

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[dmspilot]

Working on my commercial - and I have a new nemesis. The steep spiraling descent as part of emergency maneuvers during a simulated engine fire.

A question for the CFIs - what speeds and angles do you teach this maneuver at? My current CFI has me do 65 kts KIAS and almost to a 60 degree bank - this in a 172. I see some YouTube videos where the speeds are closer to 100 and bank almost to 50 -- with a good descent rate of 2K FPM.

Thanks

Edit: to add type of a/c.

The maneuver is supposed to be performed at best glide speed. The angle of bank is supposed to be adjusted to maintain a constant radius, but it is supposed to be a steep bank angle not exceeding 60°.

 

[Cap'n Jack]

Cessna 172.

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Given we are trying to maximize our descent, I would use full flaps, Vfe is still 85 knots, steep turn (45°). The idea is to get to the ground and land ASAP since the fire may be weakening the structure.

This seems another area where there is going to be a lot different answers; some of them will make more sense than others. I hope I can learn from the other ways people will describe the procedure.

How does the examiner want it done?

 

[dmspilot]

Given we are trying to maximize our descent, I would use full flaps, Vfe is still 85 knots, steep turn (45°). The idea is to get to the ground and land ASAP since the fire may be weakening the structure.

That is not the idea of a steep spiral.

 

[Cap'n Jack]

That is not the idea of a steep spiral.

Steep spiral and emergency descent are two completely different maneuvers.

You are probably correct, but given the original post specified a fire, and emergency maneuvers, I'm thinking the OP was asking about the emergency maneuver.

It would be helpful if you would explain the differences and correct terminology so we all are talking about the same thing. Thanks in advance!

 

[dmspilot]

You are probably correct, but given the original post specified a fire, and emergency maneuvers, I'm thinking the OP was asking about the emergency maneuver.

It would be helpful if you would explain the differences and correct terminology so we all are talking about the same thing. Thanks in advance!

I used the correct terminology already. They are both in the Commercial Pilot ACS. The FAA explains them.

I missed that this was simulating a "fire" which unless a typo makes no sense. Someone is mixed up, either OP or OP's CFI.

 

[ArnoldPalmer]

Steep spiral and emergency descent are two completely different maneuvers.

Isn't the purpose of the steep spiral to lose altitude quickly and descend to the field below in case of an emergency?

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[tspear]

Emergency descent can be more than just fire. Engine fire you’re right, basically cut off mixture, pitch down and haul ass until it’s out. Potential hypoxia, or loss of cabin pressure or something like that you reduce power and nose down staying below Vne. Engine out you may do a spiral staying above the field, that’s your glide speed adjusting as needed to hit the field.

Short of a slip I’m not sure why you would need to bank more than 45. An emergency descent is still a controlled descent. Keep it comfortable and out of the red...

A spiral with a steep bank takes much more energy than a slip in most aircraft.
Hence you will find many POH have between 45 and 60 degree bank, than a slip to come down fast.

Tim

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[Clip4]

The easy way to do them:

1. Reduce power to idle.
2. Enter 30-45 degree banking left turn while reducing airspeed Vfe -10
3. Incrementally increase flaps while incrementally reducing pitch to maintain desired airspeed.

 

[Cap'n Jack]

When the POH doesn't specify, then turn to the FAA's Airplane Flying Handbook. As @dmspilot pilot has pointed out, it's supposed to be performed at best glide with the bank angle not to exceed 60 degrees while keeping a constant radius turn. The ACS also provides the performance standards. Also as @dmspilot pilot has pointed out, this maneuver isn't the same as the emergency descent.

See replies above and below.

I used the correct terminology already. They are both in the Commercial Pilot ACS. The FAA explains them.

I missed that this was simulating a "fire" which unless a typo makes no sense. Someone is mixed up, either OP or OP's CFI.

I don’t think it is a typo, although perhaps a little sloppy with the terminology since both “steep spiraling descent” and “emergency maneuvers “ were used, and the simulation of fire. They way I was taught to do an emergency descent could be described as a “steep spiraling descent”, even if that actually referred to a different maneuver, and I appreciate the correction.

So how would you do an emergency descent?

 

[dmspilot]

Isn't the purpose of the steep spiral to lose altitude quickly and descend to the field below in case of an emergency?

No, the purpose of the steep spiral is to "improve pilot techniques for airspeed control, wind drift control, planning, orientation, and division of attention."

 

[dmspilot]

See replies above and below.

I don’t think it is a typo, although perhaps a little sloppy with the terminology since both “steep spiraling descent” and “emergency maneuvers “ were used, and the simulation of fire. They way I was taught to do an emergency descent could be described as a “steep spiraling descent”, even if that actually referred to a different maneuver, and I appreciate the correction.

So how would you do an emergency descent?

Referring to a maneuver using the name of a different maneuver is more than "a little sloppy." Might as well call a Lazy-8 a "Chandelle." OP needs to talk to his or her CFI.

 

[Clip4]

See replies above and below.

I don’t think it is a typo, although perhaps a little sloppy with the terminology since both “steep spiraling descent” and “emergency maneuvers “ were used, and the simulation of fire. They way I was taught to do an emergency descent could be described as a “steep spiraling descent”, even if that actually referred to a different maneuver, and I appreciate the correction.

So how would you do an emergency descent?

There is a different purpose in a steep spiral and emergency descent.

The ED purpose is to get down quick, highest airspeed with a safety margin for flap speed. Steep bank to load up the Gs - 45 degree.

The steep spiral is a slower descent to a landing site allowing for a precise approach for landing. L/Dmax + bank 30-45 for wind correction, no flaps until needed.

 

[ArnoldPalmer]

Referring to a maneuver using the name of a different maneuver is more than "a little sloppy." Might as well call a Lazy-8 a "Chandelle." OP needs to talk to his or her CFI.

I've done this maneuver twice. So bear with my "sloppiness,"...

CFI brings me over mid-field at 2000 AGL. Says you have an engine fire and need to get down now. Pulls power, says 65 knots and no more than ,60 degrees on the bank. Once three turns are done, we land on whatever run is easily accessible to us. He calls it a steep spiral descent.

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[Cap'n Jack]

Referring to a maneuver using the name of a different maneuver is more than "a little sloppy." Might as well call a Lazy-8 a "Chandelle." OP needs to talk to his or her CFI.

Or we can try to explain here, as @Clip4 has done in the post above. I learned something from his post.

 

[Maxnr]

I got this maneuver for both Comm and Inst rating. Piper PA-22. All mine were under the hood. I was never told "Why." My duty was to carry out orders. Assumed it was to get down through a hole in the overcast or something like that. Conditions were: Flaps UP. Power at 1500 rpm. A.S.=whatever. Bank at least 45 deg. Vertical speed at 500 FPM. (No +/-) Rate of descent was likely the first parameter to be exceeded if you doped off. That would call for another. After three or four, anyone could do them in their sleep. My CFI was a WW2 vet who campaigned a P-40 from N Africa, thru Sicily to Italy.

 

[MauleSkinner]

I've done this maneuver twice. So bear with my "sloppiness,"...

CFI brings me over mid-field at 2000 AGL. Says you have an engine fire and need to get down now. Pulls power, says 65 knots and no more than ,60 degrees on the bank. Once three turns are done, we land on whatever run is easily accessible to us. He calls it a steep spiral descent.

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Get a different instructor. This one obviously isn’t familiar with the ACS, nor is he making sure you’re familiar with it.

 

[Clip4]

I've done this maneuver twice. So bear with my "sloppiness,"...

CFI brings me over mid-field at 2000 AGL. Says you have an engine fire and need to get down now. Pulls power, says 65 knots and no more than ,60 degrees on the bank. Once three turns are done, we land on whatever run is easily accessible to us. He calls it a steep spiral descent.

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I call it really dumb.

The 172 stall speed @ 60 degrees bank 40 degree flap gross weight and forward CG is ~58 KIAS and you are close to the ground. With 30 degrees flaps its ~59 KIAS. With a little wind shear you are there. Then there is the mid air collision risk. Explain it to your CFI, tell him this is not a maneuver required for the commercial rating and you are not doing it.

A power off 180 is a required maneuver, but you don’t do these full flap 60 degrees of bank.

If this is a 141 school, have a talk with the Chief instructor.

 

[dmspilot]

Or we can try to explain here, as @Clip4 has done in the post above. I learned something from his post.

Two maneuvers. Steep spiral. Emergency descent. The FAA describes and explains them, I see no reason to do so myself when the FAA is the preferred source of information.

 

[dmspilot]

I've done this maneuver twice. So bear with my "sloppiness,"...

CFI brings me over mid-field at 2000 AGL. Says you have an engine fire and need to get down now. Pulls power, says 65 knots and no more than ,60 degrees on the bank. Once three turns are done, we land on whatever run is easily accessible to us. He calls it a steep spiral descent.

When was the last time your CFI trained a commercial applicant?

 

[Clip4]

When was the last time your CFI trained a commercial applicant?

Better question is how many has he trained doing this. Yes, 30 years ago the commercial had steep spiral to landing, but you sure didn’t use that method. 3 - 360 degree turns 2000 ft agl with 60 degrees bank and full flap wouldn’t work.

 

[Cap'n Jack]

@ArnoldPalmer , it seems you got the answer you were looking for in posts #2 and #15, post #15 is more correct. No need to run down anyone's instructor, nor the student who is trying to get clarification.

There is a different purpose in a steep spiral and emergency descent.

The ED purpose is to get down quick, highest airspeed with a safety margin for flap speed. Steep bank to load up the Gs - 45 degree.

The steep spiral is a slower descent to a landing site allowing for a precise approach for landing. L/Dmax + bank 30-45 for wind correction, no flaps until needed.

I thought the emergency descent was a 1 g maneuver? The steep turn helps to descend faster. My experience is that I "load up the Gs" with a 45° bank if I'm maintaining altitude. Edited because it was incorrect.

 

[MauleSkinner]

I thought the emergency descent was a 1 g maneuver? The steep turn helps to descend faster. My experience is that I "load up the Gs" with a 45° bank if I'm maintaining altitude.

Try flying a constant airspeed descending spiral with 45 degrees of bank and tell us if it’s 1 g.

 

[Clip4]

@ArnoldPalmer , it seems you got the answer you were looking for in posts #2 and #15, post #15 is more correct. No need to run down anyone's instructor, nor the student who is trying to get clarification.


I thought the emergency descent was a 1 g maneuver? The steep turn helps to descend faster. My experience is that I "load up the Gs" with a 45° bank if I'm maintaining altitude.

When you bank an airplane you are no longer at 1G due to centrifugal force and you have a corresponding increase in stall speed. The fact you are descending does not change the forces. This is why we can descend so rapidly in the emergency descent.
http://media.aero.und.edu/interactive-trainers/forces-in-a-turn/

Play with this and you will see why your CFIs emergency descent is dangerous.

From the Private pilot ACS of emergency descents. Use bank angle between 30° and 45° to maintain positive load factors during the descent.

 

[dmspilot]

@ArnoldPalmer , it seems you got the answer you were looking for in posts #2 and #15, post #15 is more correct. No need to run down anyone's instructor, nor the student who is trying to get clarification.


I thought the emergency descent was a 1 g maneuver? The steep turn helps to descend faster. My experience is that I "load up the Gs" with a 45° bank if I'm maintaining altitude.

Incorrect on all counts.

 

[luvflyin]

Steep spiral and emergency descent are two completely different maneuvers.

Wouldn’t an intentional ‘steep spiral’ be an emergency descent? I’m really having trouble getting my head wrapped around doing a steep spiral to get down fast because the engine is on fire not being an emergency descent.

EDIT: I’ve read the whole thread now. It’s a matter of definition of ‘emergency descent.’

 

[Bill Greenwood]

Seems smart to me for a commercial student to practice a emergency descent in the rare, but serious case of a fire. I didn't have a fire, but had a turb fail and landed with oil smoke blowing out.
A pilot is not likely to know the cause or size of the fire and may not be able to stop it. The other acute danger is that of fumes which may be very toxic and even one breath can put you out or even be fatal. I recall two guys in a T6 , had a fire at at 1500 ft near the airport, said they'd glide down, but 30 sec later just rolled over and went in. You have to breathe every minute or so.
As for speed and bank, remember stall speed gets faster as you bank, IF YOU ARE PULLIING G'S, and its not a linear progression, you need about a 45* bank to make a prompt turn, but if you get over a 60* stall speed really starts going up. You can bank say 50* and let the nose below the horizon and not stall. Certainly as a pilot you have practiced steep turns up to 60* and if you get near stall you take off some bank and/or let the nose descend.
Do you have to spiral or can you just dive at the runway or even slip? Might depend on where the runway or road you are trying to reach.
Don't forget to turn off fuel and or electrics if that is feeding the fire.

 

[dmspilot]

Wouldn’t an intentional ‘steep spiral’ be an emergency descent? I’m really having trouble getting my head wrapped around doing a steep spiral to get down fast because the engine is on fire not being an emergency descent.

Answered in posts 5 and 7.

 

[MauleSkinner]

Seems smart to me for a commercial student to practice a emergency descent in the rare, but serious case of a fire. I didn't have a fire, but had a turb fail and landed with oil smoke blowing out.
A pilot is not likely to know the cause or size of the fire and may not be able to stop it. The other acute danger is that of fumes which may be very toxic and even one breath can put you out or even be fatal.

Yes, it would be smart. Unfortunately the OP’s instructor made up his own maneuver instead of training the two separate maneuvers that the ACS specifies. This maneuver doesn’t comply with the ACS, nor does it have any practical value in the real world.

 

[luvflyin]

Answered in posts 5 and 7.

Gotcha. I already edited my 32. That being said, this whole thing began with an engine on fire. That's an emergency. 'Steep spiraling descent' was being used as remedy to that emergency. Irregardless of other things spiral descents are used for during training, such as recognizing them happening inadvertently and recovering from them and other things you described, in this case it was an emergency, it was a spiral and it was a descent. If it walks like a duck, quacks like a duck, it's a duck. Substitute emergency for duck.

 

[Peter Anderson]

65 knots and 60 degree bank seems like a way to get down fast because of the stall that is bound to happen.


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[dmspilot]

That being said, this whole thing began with an engine on fire. That's an emergency.

The whole thing began with practice maneuvers for the commercial checkride. The title of the thread is the title of a different maneuver which would be inappropriate for an engine fire. But the procedures described by OP also seem inappropriate for that scenario. As Maule said, the CFI seems to be making up his or her own maneuvers.

 

[MauleSkinner]

65 knots and 60 degree bank seems like a way to get down fast because of the stall that is bound to happen.


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Not fast...slow and uncontrolled.

 

[WDD]

So...... what I've been taught is that if you have a fire, descend as quickly as possible, don't exceed Vne. Don't fly at best glide speed. Head to the landing spot / field - which may not be ideal, but get down before the plane falls apart, etc. If you have to do a 360 to make your field, then do that.

I did have an instructor who taught do to spirals if you're on fire because that will drop you the quickest. But dropping the quickest doesn't do you much good if you land on top of a tree - you still have to have to walk away.

Now, if you need to loose altitude in an emergency decent but not land - that I guess is a different story. What looses altitude quicker - straight ahead below Vne, or spiral?

 

[RussR]

I hate teaching this maneuver, for many of the reasons discussed.

It's basically a descending turn-about-a-point.

But if it was to be simulating an emergency descent, then I would not be concerned with maintain a constant radius about a point - in fact shallowing the bank to keep a constant radius would mean a slower descent.

If it's to simulate spiraling down for a power-off landing, then the object shouldn't be to maintain a constant radius around a point - after all, you're not going to spiral down with your landing point at the center of the spiral. You'd offset - so the object should then be to line up with your landing surface each time around.

So it seems like just a coordination drill with no practical application. Which is fine as far as that goes - so are Lazy 8's and 8's on pylons, and chandelles to some extent. But it does make it hard to explain "why" we're doing this.

Now, the maximum bank is 60 deg, but there is no minimum bank. And "steep" is not defined in the ACS. So you can go up to 10,000 feet and make three gigantic circles at 10 degrees of bank. Or you can wrap it around in a tight 60 deg bank from a lower altitude, as long as you recover by 1500 ft AGL.

CFI brings me over mid-field at 2000 AGL.

As mentioned above, this can't possibly be a "steep spiral" as defined in the Commerical ACS, due to the required recovery by 1500 AGL. I would chat with your instructor based on what you've found out in this thread.