Emergency descent in an Arrow

jynxyjoe said:
Arrow hu?

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Oh my.

drunkenbeagle said:
Don't exceed any aircraft limitations! 30-45 degrees bank, drop gear when you can for drag, then drop flaps, don't shock cool the engine (going to idle in a fast descent is bad), prop not to exceed redline. You want to have the prop full RPM once you slow down, and slowly power back the engine. Vne, Vle, Vfe are the big limitations to watch, Va if in rough air. That said, you want to be as fast as possible to maximize drag.

Refer to the FAA's Airplane Flying Handbook (it is in there), the POH for the airplane supersedes that though. I think it is fine to brief the examiner that in a real emergency you would go power idle/prop pitch immediately, but not for a practice demonstration. Also, the nature of the emergency changes things - for a structural failure, we would want to minimize loads on the aircraft. For a fire, we would want maximum airspeed, etc.
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We did it in the 'nole at full fine pitch, idle power, gear down, flaps up, 45-degree bank and airspeed a gnat's whisker below Vle.
 
I did one on my checkride (of course that was 11 years ago)... I think it was done in a simulated pressurized loss of pressurization scenario.

Another type of emergency descent I've seen is the medical emergency. Where getting down to the ground isn't the priority (no 45 degree bank to come straight down), but getting to an airport as fast as possible is. Flaps up, gear up, nose point to the airport, throttle and pitch to keep below Vne (or Va if needed), call to have medical people standing by, transition to land safely...
 
I'm not going to dispute what the checklist says for a given aircraft, but I'm surprised to see that flaps would be extended during an emergency descent for any airplane. Any time I've done one, or been called on to do one, it's always been relatively the same procedure - Throttle to idle, props full forward, drop the gear and initialize a rapid spiraling descent just below Vle.

Seems kinda contradictory to add drag when your biggest concern is getting down as quick as possible. I can see why the gear would be down, though - So that you can put the airplane down immediately, should you need to.
 
FDX8891 said:
Seems kinda contradictory to add drag when your biggest concern is getting down as quick as possible. I can see why the gear would be down, though - So that you can put the airplane down immediately, should you need to.
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For us who fly non-draggy twins, the point of gear extension is indeed "MORE DRAG" - not immediate landing. If I put the nose down in the Twin Bonanza all that will happen is the airspeed increases, so I need to have the rubber-coated speed brakes extended.

Drag we want plenty of, lift, not so much.
 
Autothrust Blue said:
For us who fly non-draggy twins, the point of gear extension is indeed "MORE DRAG" - not immediate landing. If I put the nose down in the Twin Bonanza all that will happen is the airspeed increases, so I need to have the rubber-coated speed brakes extended.

Drag we want plenty of, lift, not so much.
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My reasoning is that I understand aerodynamic drag to be a retarding force, and that it always acts parallel to and opposite of the aircraft's flightpath. The more drag you have, the more of a retarding force there is against the aircraft's flightpath, which is why it doesn't make sense to me to put down flaps during an emergency descent.

But, then I think about why we use flaps for landing..it does make sense.

I don't know, my final answer is just to do whatever the checklist says.
 
With the power at idle and the prop full up, it will drop faster with the flaps down than up. Granted your forward speed won't be as great given the airframe limits/flap/gear extended restrictions, but the point is to get down fast.
 
I don't recall doing an emergency decent of either CSEL, or my CFI initial. I remember practicing the manevuer, though.

In the Arrow, it was:

1. Throttle to idle
2. Prop full forward
3. Below 129 KIAS (Vlo), extend landing gear
4. 30º bank and pitch to maintain 129 KIAS (takes a surprising amount of forward pressure on the yoke)
5. As you're turning, clear the area below.
6. As you approach your desired altitude, level the wings and gently begin to pitch up to stop the descent and simultaneously bring power back to cruise
7. When descent has stoppe, check airspeed & raise the landing gear while still below 107 KIAS
8. Resume cruise flight

There was also an option to extend full flaps, but you have to slow to 103 KIAS (Vfe) before extending the flaps and then maintain 95 KIAS in the descent. More workload & more opportunity to screw up that way, imo.

Used the same procedure in the Seminole, except had to pitch for 140 KIAS in the descent. Pretty awesome descent rate, though
 
Mike H said:
There was also an option to extend full flaps, but you have to slow to 103 KIAS (Vfe) before extending the flaps and then maintain 95 KIAS in the descent. More workload & more opportunity to screw up that way, imo.
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Half flaps, as it is with many aircraft, was probably a good compromise between descent rate, and downrange travel.
 
///AMG said:
Half flaps, as it is with many aircraft, was probably a good compromise between descent rate, and downrange travel.
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Not really in most of the cherokee family, as they typically have one flap speed for all settings. Might as well drop full flaps, you still have the same max forward speed and will get a greater descent rate. Would be different in a Cessna, they typically allow some flaps at a higher airspeed.
 
Roger said:
Not really in most of the cherokee family, as they typically have one flap speed for all settings. Might as well drop full flaps, you still have the same max forward speed and will get a greater descent rate. Would be different in a Cessna, they typically allow some flaps at a higher airspeed.
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Fair enough....I wasn't as much talking about flap speeds as I was the difference in drag at half and full flaps. None of the aircraft I have flown in the past 5-6 years have had more than one flap limit speed, but throwing in full flaps just adds a whole ton more drag. Can be good for various reasons, but the extra drag costs forward speed unless you really add in a whole lot of power. In this particular scenario, ideally you not only get down quickly, but also get to a suitable piece of conrete to land on quickly as well....hence what I meant about it being a trade-off
 
///AMG said:
Fair enough....I wasn't as much talking about flap speeds as I was the difference in drag at half and full flaps. None of the aircraft I have flown in the past 5-6 years have had more than one flap limit speed, but throwing in full flaps just adds a whole ton more drag. Can be good for various reasons, but the extra drag costs forward speed unless you really add in a whole lot of power. In this particular scenario, ideally you not only get down quickly, but also get to a suitable piece of conrete to land on quickly as well....hence what I meant about it being a trade-off
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Right, but in an emergency descent scenario with flaps in you are going to be pitching for Vfe with power at idle. Therefore, if VFe full is the same as Vfe half, then you'll be pitching for the same airspeed regardless, and going full vs. Half flaps would give you a greater descent rate for the same forward speed (essentially) which in most emergency descent situations would be optimal. If you're using flaps at all. Which, none of the aircraft I've done emer descents in used flaps (at least as standard procedure, as always procedure could be adapted to fit the situation)
 
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