Forced Approach - Best Glide Speed

[iflyforpie]

I read somewhere that Sulley set the plane up for Best Endurance (just below Best Glide) to give himself time to think and the cabin crew time to prepare when he realized he wasn't going to make an airport.

Best Endurance is also good with a tail wind, since you will cover more distance than Best Glide.

Into wind, you want Best Penetration, which IIRC is about 1/4 of the headwind added to Best Glide.

But yeah, no point in messing around if you've got a field in range.... just don't screw it up.

I didn't use best glide for my real forced approach. I cranked it until the stall horn went off to turn back to the field and pitched for a normal power off approach speed. I made the field, and didn't put a scratch on the aircraft.

[Colonel Sanders]

I didn't use best glide for my real forced approach. I cranked it until the stall horn went off to turn back to the field and pitched for a normal power off approach speed. I made the field

Sharp flying, IFP! Congratulations on
really learning to fly, despite what you
were taught.

[AirFrame]

I didn't use best glide for my real forced approach. I cranked it until the stall horn went off to turn back to the field and pitched for a normal power off approach speed. I made the field, and didn't put a scratch on the aircraft.

You turned back to the airport after an engine failure? But... but... that will kill you!

[Colonel Sanders]

Anytime you're going 100 mph or are
100 feet off the ground, you have enough
kinetic or potential energy to kill you.

It's odd how people think some maneuvers
are more Politically Correct than others.

A doctor near me, tried to fly an vectored
ILS one night. He and his pax are dead
now. But people are still flying ILS's, last
time I checked.

But if you teach someone the EFATO, you're
a Bad Person. Much screeching and honking
ensues.

How odd.

I use 90 degrees of bank in the circuit, all
the time. Never stall. Never even implode
with a singularity caused by infinite G. Hell,
I fly the downwind inverted.

This makes you a Bad Person, if you
develop skill and knowledge.

I have never understood the peculiar calculus
of Political Correctness, which seems in no
small part to be advocating ignorance.

www.pittspecials.com/articles/bank.htm

[Big Pistons Forever]

You turned back to the airport after an engine failure? But... but... that will kill you!

Yes unfortunately that is the all to common outcome, like the tragedy at Nanaimo last weekend.........

[CpnCrunch]

ifly: what height were you at when you turned back?

[Rudder Bug]

ifly: what height were you at when you turned back?

That's a good question, I'd like to know as well...

RB

[cgzro]

Most of the planes I fly have poor visibility forward and best glide does not improve visibility. I would want to be banking and slipping to look and find the best field possible rather than glide as far as possible to a bad field. In fact many years ago I had this lesson brought home when an evil instructor pulled the power right over a beautiful private grass strip that i could not see.

[Shiny Side Up]

PUT ON THE SHOULDER HARNESS

I actually had a debate (via email) with a noted expert regarding this, since it was their opinion and experience that you might want to not have it on so you could bail out quicker upon coming to a stop. I know a guy who was killed in what should have been a survivable crash not wearing one, so needless to say I had a differing opinon.

Either way, there might be a lot of ways and things you might do on a forced approach that depend on your circumstances when it happens. I had one once where just holding the glide was just right to get it to the runway. In that case, it might be argued that getting that under control to stretch the last bit of distance out of it was the solution. Might not always be.

The chief problem is that the forced approach, like a lot of things has taken on a life of its own for the purposes of the flight test, and has gotten farther away from the reality. Lets be honest, the excersise isn't representative of most forced approaches, and really only what it might be like in a reasonably glideable piston four-seater. Needless to say you won't be able to cover all scenarios during the training for a PPL, and as you're fond of pointing out its more important to train them how to avoid having to end up in a forced approach.

When I teach instructor students, basically every flight ends up in a forced approach to the runway. That ends up with a lot of scenarios and a lot of things to think about. Its also not the canned precision 180 exersise. They do it with crosswinds, tailwinds, from any position I know we can glide back. We'll do turnbacks. The thing is though, like anything, to be proficient at this sort of skill, you do it over and over and over, ad nauseum. Most PPLs, though, the last time they might do this practice is going to be on their flight test anyways. Do you think in the average PPL's less than 30 hours a year they're going to spend much time keeping this sharp? Not likely. The only thing that teaching "get it gliding" does, is hammer home the get the freaking nose down, and hope that if it happens in the rest of their years flying that they'll remember that.

Something interesting on the topic: Cessna neatly provides for one a cloud breaking procedure, which incidentally works good as a forced approach procedure if one was unfortunate enough to have one at night or in cloud. It sets the airplane up so it descends at a low rate in a slightly nose up attitude. The idea being that if you're likely to run into something on the way down, it puts you in a favorable way to crash the airplane. Lowest forward speed. Keeps the pilot from putting it into a spin by telling him to keep his damn hands off the controls. Reminds him to do up his seat belt. In some ways, its what should be taught to most PPLs who aren't going to maintain proficiency so realistically they can more survivably crash airplanes. Not that crashing airplanes is cool, but then I don't view maintaining a minimum proficiency at what is a somewhat risky activity cool either. Your opinion may differ.

[Colonel Sanders]

See "Tale of Two Comanches".

Despite all the obfuscation, avoidance of
unintentional stall/spin is the most important
objective of any forced approach.

It's really very simple:

If you accidentally stall/spin during a forced
approach, you will almost certainly die.

If you do not stall/spin during a forced approach,
you will almost certainly live.

I find it greatly disappointing that after all
these decades of poor performance on flight
tests and in real life, so little emphasis is
placed upon this. So little is learned. Mistakes
are repeated, year after year, decade after
decade.

Instead, we have people doing all sorts of
useless, distracting housekeeping in the cockpit,
instead of:

FLY THE AIRPLANE

and

PUT ON THE SHOULDER HARNESS

Learn to ruthlessly prioritize. No f__ks given
to people who are trying their best to distract
you from doing your job.

This guy lost an engine after takeoff. How well
did he prioritize?

http://www.youtube.com/watch?v=YqmomTUVsAw

[Docbrad]

I never like watching when you post these types of videos, but I always do. There's a lesson to be learned... Gotta fly the airplane. That's #1

[iflyforpie]

I was at about 300'.

I was fortunate to have a light headwind, and even more fortunate to have a powerful aircraft well under max gross that was able to make that height a decent distance from the field. Fully loaded on a hot day in an anemic aircraft, no way you are making it back.... fancy skills cannot change the laws of physics.

Also..... fortunately..... I was taught that maneuver by a Class 1 Aerobatics instructor during an Emergency Maneuvers training course I was provided with by a previous employer.....

Like CS says..... so many pilots try to teach themselves surface level aerobatics in the few seconds they have before hitting the ground.

[Colonel Sanders]

I was taught that maneuver by a Class 1 Aerobatics instructor

You are lucky to have received some competent
flight instruction. It is getting rarer and rarer,
these days. I thought you had figured it out on
your own, which impressed the hell out of me

I learned to do the turnback from a Professor
(now retired) at the USN Academy, a guy called
Dave Rogers, who did some interesting research
into this particular maneuver. God, that must
be 25 years ago now. And still, no one understands
it. How depressing.

Teaching EFATO turnback is very politically
incorrect. You must do it quietly, for some
bizarre reason. Eric and I have thought of
making a Youtube video, with ground briefing
and footage from inside and outside the aircraft,
but it's just not worth the hassle we would
get for it.

Like a +ve G aileron roll, the turnback is a
childishly simple maneuver. I can generally
teach anyone to do either one, in under five
minutes. But still, people come to terrible
grief with them.

At the risk of annoying more people, could
I say three words, which the Queenair pilot
could have perhaps thought about?

LOWER THE NOSE

After an EFATO in either a single or twin, you
must

LOWER THE NOSE

to maintain flying speed. More correctly, to
keep your alpha down. Don't overdo it and
go -ve G, for chrissakes. Just let it float down.

Very light G, if you are interested.

Learn to do that maneuver wings level. Then
learn to do it while you are also turning, at the
same time.

If you are gentle with the aircraft, fly it with
light G, your stall speed is very low.

In fact, I can fly any aircraft (at low altitude,
the wings have no eyeballs) at 80 degrees of
bank without stalling it ... as long as the G is
low.

Specifically, the stall speed of any aircraft in
a 80 degree banked turn, at zero G, is ZERO MPH.

It is a tragedy that 99% of pilots do not understand
this little detail. They spend their entire lives,
using airspeed as a proxy for AOA, which saddens
me.

Once you start thinking about the wing, and using
the Cl curve, you can do magical things with an
aircraft, which will frighten your friends and get
TC on your case, for the rest of your life.

http://www.youtube.com/watch?v=Fcy4ZhGHHaE

It can get depressing, sometimes. Over 50 years
ago, my father was teaching the same lessons about
the difference between airspeed and AOA, when he
was an instructor pilot on the F-104, to transitioning
Sabre pilots. They had heard that the -104 was a
fire-breathing dragon that could not be slowed
down safely.

Male Bovine Excrement, my father would say, and
they would pitch vertical, throttle back and when
the ASI dropped below 40 knots, do the prettiest
"stall turn" (he calls it - hammerhead) in the -104,
watching the equivalent AOA indicator the entire time.

In the vertical downline, leave the throttle idle, go
supersonic and pull level again.

Anyways. I guess we are Bad People in my family,
but we can sure fly a f__king airplane.

Ninety-seven years in aviation. Maybe - just maybe -
we might have a clue.

[rob-air]

CS the ideas you put down on virtual paper is gospel to ''experienced pilots'', but to 45 hrs ppl's it probably sounds like chineese. You just cant expect pilots to understand in a few months what took nearly a century to come up with. But keep em coming.

[Colonel Sanders]

Ok. I'll take another swing at it.

You know what "G" is, right? Sitting in your
chair, you're experiencing +1G. In a steep
turn, you can experience +2, +3 or +4G.

You can also decrease the G, too, by gently
pushing forward on the control column.

Here's the one fact I want you to learn:

Vs(G) = sqrt(G) x Vs(1G)

You can derive it from the lift equation. It
tells you the relationship between G and
stall speed.

At +2G, your stall speed increases 1.4x
At +4G, your stall speed increases 2x

And at 0G, your stall speed is ZERO. This
is because you aren't asking the wings to
produce any lift, so they can't stall.

Think of the airplane, parked in the hangar.
Airspeed is zero, but the stall warning isn't
going, because you aren't asking the wings
to produce any lift. The landing gear are
doing all the work.

If you can spend the time to read and re-read
the above until you understand it, you are
a long way along the journey of actually
understanding the theory of flight.

Like the above? Keep reading, here:

www.pittspecials.com/articles.html

[Shiny Side Up]

The thing is Colonel, the point is really moot. If people are bad at doing forced approaches, I can't see how they'd be better at doing EFATO turn backs. The key is practice. Now its not that complicated of a maneuver, but neither is landing and see how often pilots botch that up - and that's something they probably do the most of besides take offs and flying straight and level (and I've seen people who aren't even very good at that). Again, in my experience, 90% of the reason is practice. No one does it. Most pilots even if they do fly a lot, do very little besides take off, fly straight, land.

We can harp all we want on people improving their technique at stuff like this, but if they aren't going to go out there and give it the attention it deserves, they might as well just follow the simple steps I gave in the previous post for survivable crashes. Shit there were some guys a while back who survived falling asleep in the plane until it did just that. I wish we could ask for more, but the world is insistent that we don't.

Personally I don't teach turnbacks to PPL students. I can't control what kind of pilot they're going to be when they leave my nest. If they want to come back to get better at that sort of stuff, that's up to them.

Something I experienced a little while ago. Had a new instructor, was all about turn backs, he was shown one once, it apparently was awesome so that was now part of his lexicon and personal teaching. Funny thing though, he had only ever done one once, I could picture him and his old PPL instructor doing some fist bumps after that, where it was then counted as a win and never revisited. So during our initial training after he confidently gives me his "if it fails in the air, I'm going to make it back" I said, well lets try that out, and even knowing it was coming, you can probably guess the result. Well short of making the runway, if we even could have got back over onto it. Made the mistake of turning with the wind, added to the snail's pace mental checklist he was taught.

It would be humorous if the implications weren't so distressing.

I should say I do that to everyone on a checkout who says they're going to be heroic when the worst happens. So far I think its zero for thirty, but I've lost track. Lots of people like to read the magazines, surf the net and talk a big game.

Now I can do it here, and the runway here ain't blessed in an ideal fashion for the purpose, but I do something similar to what Pie describes, and when I do it as a demo to instructors, usually it ends up with some one in the seat beside me white as a ghost, sweating profusely and lots of the time grabbing the upholstery in a panic.

But then I, like you and a few others, practice a lot. People are always surprised when I tell them I'm going to just go out and fly with no destination and "make sure I'm shined up".

[Colonel Sanders]

I get your point, SSU. I fly about 300 flights
a year, which isn't a whole lot, but it's enough
to keep the rust off.

What I find is a great introductory maneuver
is the wingover, which is a required maneuver
on the FAA COMM checkride. At the apogee,
they are at a steep bank angle with very little
airspeed on, ball in the center and a low AOA.

Hmm.

[AirFrame]

Everything else you've said in this thread makes total sense, except this one thing...

Specifically, the stall speed of any aircraft in
a 80 degree banked turn, at zero G, is ZERO MPH.

What makes you turn, if you aren't creating a force vector towards the inside of the turn?

[photofly]

Everything else you've said in this thread makes total sense, except this one thing...

Specifically, the stall speed of any aircraft in
a 80 degree banked turn, at zero G, is ZERO MPH.

What makes you turn, if you aren't creating a force vector towards the inside of the turn?

LOL. He's got you there...

[Big Pistons Forever]

The thing is Colonel, the point is really moot. If people are bad at doing forced approaches, I can't see how they'd be better at doing EFATO turn backs. The key is practice. Now its not that complicated of a maneuver, but neither is landing and see how often pilots botch that up - and that's something they probably do the most of besides take offs and flying straight and level (and I've seen people who aren't even very good at that). Again, in my experience, 90% of the reason is practice. No one does it. Most pilots even if they do fly a lot, do very little besides take off, fly straight, land.

.

I think this is the essence of the issue. To safely do the turnback you first have to have pretty good foundation stick and rudder skills and those foundation skills require discipline on the pilots part to attain and then maintain.

The guys and it always guys, that talk a good line about how if the engine fails they are just going to rip her around and land back on the runway........well usually are the guys who's ego's write cheques their ability can't cash.....

Going back to the original posters question. The first challenge is to actually be able to go to the glide attitude and hold it. I hardly every see that, instead there is a lot of the nose bobbing up and down and the speed wandering all over the place. The second issue with the OP's question is the speed doesn't matter as much as the ability to recognize whether the flight path of the aircraft is going to get you to your intended touch down point. This is a skill that can only be developed with practice. The good news is you can make any landing a glide approach and closing the throttle at various points in a normal circuit and see how you do with making your touch down point is an excellent and inexpensive way to develop and then maintain the skill that is most important part of flying a forced approach.

With respect to the engine failure after takeoff and the turn back here are my 02 cents, and worth every penny you paid for them

1) The probability of fatalities in any accident is highly correlated with 2 things the attitude the airplane is in when it hits and the deceleration Gee force. If you hit the ground in a slight nose up attitude with the wings level you are almost certainly going to survive. If you hit the ground in a steep nose down banked attitude you are almost certainly going to die.

If you hit a solid immovable object head on, while still in the air at flying speed you are probably going to die, if the airplane has any room to travel before it stops, even if only a few feet, you are probably going to live. A 60 kt to zero kt 9 Gee deceleration only requires a run of about 25 feet or one airplane length. 9 Gee means when the airplane stops you undo the seatbelt, open the door and walk away uninjured.

2) The accident rates suggest that a turnback is 8 times more likely to result in a fatal outcome than a straight ahead landing even if it is into the side of a house or trees etc etc. This because of the fact that so many turnbacks result in a stall spin with the resultant near vertical hit.

3) The window of vulnerability for the EFATO scenario is a very small portion of every flight. The chance you will be in the turnback window when the engine fails vs some other part of the flight experiencing an engine failure is very small. Therefor if you take the position that you should practice emergencies in the order of their probability then there are many others things that should be practiced before EFATO turn backs

4) The accident stats show that at least 80 % of all engine failures are caused by the actions or in-actions of the pilot . The best way to deal with the EFATO emergency is to not cause the engine to fail in the first place.

5) There is IMO no good way to train for the turn back manoever. Practicing at altitude is negative training because there is no ground rush and you know the engine is going to fail. Practicing it at low altitude is IMO so dangerous that the risks far out weigh the benefits and you still have the problem that you know the engine is going to fail.

The reality is if you are going to bend some metal it won't be because the engine failed, it will be because you could not fly well enough to control a perfectly working airplane on a landing or takeoff. Don't want to be "that" guy ? Simple; practice landing and takeoffs with the goal of meeting the following accuracy metrics

Speed: + - 2 knots up to 1000 AGl for the takeoff and from 1000 feet AGL to touch down for the landing

Flight path: at 500 feet AGL on final the airplane will fly a straight line from 500 feet to the start of the flare

Touchdown point: The wheels touch (in the correct nose up attitude !) - 0 feet and no more than + 200 feet from the pre chosen touch down point

Line up: the aircraft is never more than 2 feet from the runway centerline and for crosswind takeoffs there is no drift at lift off and the extended centerline of the runway is maintained until the first turn.
For landings the aircraft's flight path is aligned exactly with the runway centerline at the moment of touchdown such that there is no sideways drift at touchdown.

If you can't meet that standard on every takeoff and landing then IMO you are not good enough to be able to safely fly a turnback. If you are good enough, congratulations as you are in the top 2 % of all PPL's.....

[Colonel Sanders]

What makes you turn

In my example of an 80 degree banked
turn with zero G (and hence zero stall
speed) you have unloaded the wing, and
you allow the aircraft to continue ballistically
as determined by it's previous maneuvering.

The aircraft has mass, and thus it has
momentum and kinetic energy.

However, the aircraft is in an 80 degree
banked turn, and cannot stall. This
is blatant heresy for many, I understand.

It can be quite useful to learn to "unload
the wing" in this manner. It has many
applications.

Learn to do a nice wingover. It is a very
illuminating maneuver, especially with
90 degrees of bank at the apogee.

you are not good enough to be able to safely fly a turnback

I would be very surprised if even 1% of
the pilots in Canada were skilled enough
to perform a turnback. More like 0.001%

[Shiny Side Up]

you are not good enough to be able to safely fly a turnback

I want a t-shirt that says that.

[Big Pistons Forever]

A guy once showed me video he took a few years back. It was of a C 180 taking off from a short rough gravel strip. The airplane was parked at one end and the video starts with the pilot starting the engine and almost immediately going to full power and roaring down the runway. When the aircraft was about 300 feet AGL the engine quit cold . The guy wracked the airplane around in a 60 deg bank and then made a wild low level wings level skidding turn to line up and just made the strip with a heavy stalled on 3 point landing. The airplane rolled to stop undamaged.

"Isn't that just incredible flying" the guy said. I replied with "why did the engine fail ? " Oh he left the fuel selector in the off position and the engine failed when it used up the gas in the lines "

[AirFrame]

In my example of an 80 degree banked turn with zero G (and hence zero stall speed) you have unloaded the wing, and you allow the aircraft to continue ballistically as determined by it's previous maneuvering.

I'm not trying to be thick here, but i'm still not getting it and I want to understand... Ballistically means you'll continue in a straight line (as viewed from above), but you'll lose altitude the farther you go. A ballistic curve won't bring you back to the airport without the wing generating lift, or maybe the rudder skidding you around? We're still talking about turning back after an engine failure, right?

I would be very surprised if even 1% of the pilots in Canada were skilled enough to perform a turnback. More like 0.001%

Happy to admit that i'm part of the 99%. But it won't stop me from practising.

[Colonel Sanders]

We're still talking about turning back after an engine failure, right?

No. I am trying (in vain) to try to teach people,
by using extreme examples, that bank angle IS
NOT EVIL as you have been taught, and as your
instructors have been taught, and as their instructor
were taught. Blind adherence to religious dogma.

In an EFATO turn, I would not use 80 degrees of
bank and zero G, which is an intellectual exercise.

I would use 60 degrees of bank and light G, with a
low AOA. Really easy, simple and safe. Why people
struggle with it, defies my imagination. There are
many difficult things you can do in an airplane. The
EFATO turnback is not one of them.

If you are capable of tying your shoelaces, you
can learn the turnback. Assuming you have competent
instruction, which is the hiccup.