Forced Approach - Best Glide Speed

[Colonel Sanders]

Year after year, decade after decade, pilots struggle
with the forced approach on their PPL and CPL flight
tests. Probably the most-often flunked exercise.

If we go to the flight test guides, the first thing TC
wants to see, for the forced approach is the best
glide speed.

Sigh. What terrible prioritization.

The most important thing in a forced approach, is
maintaining control of the aircraft - no stall or spin.

The second most important thing is making the field.

It would be nice if you switched fuel tanks at some
point, but frankly, if you NEED to maintain the best
glide speed, to try to stretch your glide to a distant
field, you need to choose a closer field.

Good example. Let's say I'm at 10,000 feet directly
overhead a long paved runway and my engine quits.
Do I need to maintain my best glide speed? Male
bovine excrement. What I need to do is:

1) not stall or spin (* see below)
2) make the runway

Assuming a descent rate of 700 fpm, 10,000/700 =
FOURTEEN FRIKKEN MINUTES to glide down.

Ok, I'm a poster child for ADHD and borderline
narcoleptic, but I just don't have the patience to
wait 14 minutes to do a forced landing. I have
other things to do, today.

So if I'm at 10,000 feet overhead a nice long
runway and the engine quits, and I can't get
a restart, it's time to do some aerobatics on
the way down.

I'd start with some rolls, loops, 1/2 cuban-8's,
a hammerhead or two, and perhaps some
snaprolls and spins to lose some altitude.

At no time during that aerobatic sequence
would I be worrying about my best glide speed.

Lest you think I am insane, the above is
exactly how contest glider aerobatics is
performed. The glider - with no engine -
is towed up to altitude, and does some
purty flying on the way down.

Generally ends up with flying a very low
downwind - so low you can't see them
behind the buildings and trees - and fast,
then popping up for the final.

Executive summary: what's important
in a forced landing:

1) no (unintentional) stall or spin, and
2) make the field

It's hard to think of anything less important
than maintaining best glide speed, but
examiners will all tell you it is.

[Pop n Fresh]

Excellent point. Angels drive in here used to make an incredible chocolate mint milkshake.

Maybe we should caution students to keep a nice light positive G load while doing this in most light single training aircraft.

I would probably spend that 14 minutes making annoying calls on the radio, switching fuel tanks, trying to get a re-start, (assuming we did not do something obvious like break a crankshaft ) chatting about tightening your seatbelt, taking sharp things out of your pocket, stashing your glasses...

I don't see the downside to trying to use best glide speed to give myself extra time for that stuff. Guess I'd rather savor a whiskey than gulp a shot of vodka. Doesn't mean I disagree with your plan.

[Changes in Latitudes]

Why not turn on the smoke and write your name on the way down, too? I'd dot the i with a smiley face, but that's just me.

[Pop n Fresh]

I had to wipe spray off the screen. At least I must be fairly hydrated.

[Colonel Sanders]

write your name on the way down

Crowd prefers a heart.

PS If there's one thing I want to see a student do,
during a forced approach (other than not accidentally
stall/spin), it's

PUT ON THE SHOULDER HARNESS

At least as important as making the field. Maybe
more important.

[Pop n Fresh]

There's no "I" in Sanders?

[Colonel Sanders]

There's no "I" in Team America!

[Colonel Sanders]

On the subject of carb heat. Someone is going to
start whining about the importance of carb heat,
any time now.

If you've actually choked up the carburetor with
ice to the point that the engine is windmilling,
putting on the carb heat is like closing the barn
door after the horses have left.

It might make you feel good, but it's not going
to do much good. The windmilling engine's
exhaust has cooled off, and isn't going to
provide warm air via the carb heat to melt
the ice.

[Pop n Fresh]

Further, was there no indication of carb ice before the engine quit?

At any rate are you aware of this?

I intend to take my wife to see a re-screen this evening.

[Colonel Sanders]

Amazing! Your wife will watch Monty Python with you?

re: symptoms of carb ice ....

Back in the day when we had floppy disks, they had this
red light that would go out, 2 seconds after it stopped
writing to the disc.

I told people they could actually take the floppy disk
out 2 seconds before the light went out, but I'm not
sure they paid much attention.

http://en.wikipedia.org/wiki/Causal_filter

In signal processing, a causal filter is a linear and time-invariant causal system.

The word causal indicates that the filter output depends only on past and present inputs.

A filter whose output also depends on future inputs is non-causal, whereas a filter whose output depends only on future inputs is anti-causal.

Systems (including filters) that are realizable (i.e. that operate in real time) must be causal because such systems cannot act on a future input.

Control theory is not only insightful, it
is hilarious. Have I told you my joke
about Polish pilots in right echelon?

[tiggermoth]

So if I'm at 10,000 feet overhead a nice long
runway and the engine quits, and I can't get
a restart, it's time to do some aerobatics on
the way down.

I'd start with some rolls, loops, 1/2 cuban-8's,
a hammerhead or two, and perhaps some
snaprolls and spins to lose some altitude.

Like this guy for example

https://www.youtube.com/watch?v=7ESpjLQYfJU

[Pop n Fresh]

Similarly a guy told us about a service call he once did for a company computer. The person said their computer would not turn on. On arrival they demonstrated the problem by turning the switch on then turning it off because the unit did not power up.

The electrician said, "Turn it on again." Then when the person did he quickly said, "Step back." The person did and was now out of reach so they could not turn the switch off, then computer powered up.

They were surprised and asked, "What was wrong."
The electrician said, "You were standing on the cord and the electricity couldn't get through."

Amazing! Your wife will watch Monty Python with you?

I just asked if she wanted me to call my dad to watch the kids so she could go with me or watch the kids herself? I'll report back with results of my little scheme.

[photofly]

There's a slight misinterpretation of the flight test guide here. It says initially pitch for the recommended speed, +10 -5kts. Thereafter, you can vary your speed as required, to achieve a successful landing. Pilot's discretion.

Honour satisfied all round?

[AOW]

There's a slight misinterpretation of the flight test guide here. It says initially pitch for the recommended speed, +10 -5kts. Thereafter, you can vary your speed as required, to achieve a successful landing. Pilot's discretion.

Honour satisfied all round?

I'll bet you that more than 99% of actual forced approaches do not happen on flight tests.

[RonReynolds]

This is a good point, it's been my experience that a candidate will often fly the best glide all the way down from 3000' (AGL) in spite of of any scenario they have been presented with. A result of some single dimensional training I presume. The training should include more situations that include fires that do not go out, or extremely bad vibrations... etc, etc that motivate the student to switch up the routine and adjust.

I would like to see a bit more reference to the emergency checklist as well. Complete all initial actions from memory and then pull out the checklist and confirm that you have completed all the items, and as is typical you will certainly have the time for this.

With respect to the Flight Test requirements there is no requirement to fly best glide to the surface. The guide requires that you set best glide initially, following that it is permissible to vary the speed as you see fit.
The thing that I want to see is whatever speed you fly is by design and that you when you reach the landing phase of the approach you are at your pre-declared speed and configuration.

[CpnCrunch]

Perhaps also spend more time during training doing EFATOs at 500ft on the climbout, rather than engine failures in the circuit (which in comparison is pretty benign). As far as I can see there isn't even an EFATO on the CPL flight test.

Frankly it pisses me off when I see two high-time pilots kill themselves by spinning their plane into a perfectly good golf course 5 mins from my house when their engine quits at 300ft (as happened last week).

[photofly]

There's a slight misinterpretation of the flight test guide here. It says initially pitch for the recommended speed, +10 -5kts. Thereafter, you can vary your speed as required, to achieve a successful landing. Pilot's discretion.

Honour satisfied all round?

I'll bet you that more than 99% of actual forced approaches do not happen on flight tests.

True, but CS was railing against TC's requirement, which is only of interest on flight tests. TC doesn't care what you do in a real forced approach.

[Pop n Fresh]

There's a slight misinterpretation of the flight test guide here. It says initially pitch for the recommended speed, +10 -5kts. Thereafter, you can vary your speed as required, to achieve a successful landing. Pilot's discretion.

Honour satisfied all round?

I'll bet you that more than 99% of actual forced approaches do not happen on flight tests.

True, but CS was railing against TC's requirement, which is only of interest on flight tests. TC doesn't care what you do in a real forced approach.

Oh? They might not be fussy about the glide speed but if you have to do a forced approach they will be pretty interested.

[photofly]

Oh? They might not be fussy about the glide speed but if you have to do a forced approach they will be pretty interested.

If you hold an OC, or if someone gets hurt, maybe, and in the latter case the TSB is interested rather than TC. Unless you bust some regulations or are suspected of such, then I don't think transport has the budget to care. If you have an interesting story or TSB report they might print it in an aviation safety newsletter, I guess. That's my impression.

[Pop n Fresh]

I was thinking of TSB being part of Transport. Sorry,

[Cat Driver]

One of the most interesting factoids I noticed about how most flight instructors think when I had them in my employ was their fear of what Transport thinks.

T.C. is like a religion, they motivate the sheep through fear.

When faced with a forced landing due to engine failure the last thing anyone with any ability for critical thinking will worry about is what Transport thinks

[Adam Oke]

Best Glide is the tip of the ice burg. Most glider pilots hardly ever use best glide and are more concerned about effects of wind and how it effects the glide ratio. If you read up about polar curves, this will give you some insight. It's all about penetration .... not a specific speed.

If you're at your best glide, and not going anywhere because of the wind ..... lower the nose and punch through the wind. This will effectively increase your glide ratio. Lower the nose as much or as little as you need to make the field (within reason). Just be sure to use all of your bag of tricks to make the field.

[Pop n Fresh]

Git to work on that RV so you can bring it out here to lurn me some glidin.

I'll feed you steaks and some crescent rolls.

[PilotDAR]

"best" glide speed. "Best" for what? Perhaps the pilot would like to make it to shore, thus "best" would be greatest distance achieved for vertical descent. But this speed will hardly be "best" for a safe flare and landing. A faster speed will be better for that.

I discussed this theme in my thread on "height velocity curves" for light planes. There are speeds at which one could glide, which will certainly not result in a safe landing in some conditions.

[Pop n Fresh]

Amazing! Your wife will watch Monty Python with you?

Went quite well. It was kind of like live theatre broadcast so she liked that. There was a older lady beside her doing commentary and laughing so she liked that. She loves popcorn and going to movies so she liked that. The digital feed did not record properly so they gave everyone passes and being more than half Scottish she loved that.

She then went on to claim, "I've watched Monty Python movies. I knew some of those songs."

It was pretty good. If they are still re screening near you I recommend going. I'm not certain it's DVD worthy unless you are a collector.