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Glide approaches as standard

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Old 2nd Jul 2005, 17:46
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Glide approaches as standard

Dear all

There seems to be a minority view by respected aviators who believe that we should carry out glide approaches as standard procedure (take, for example, Jerry Eichenberger in "Your Pilot's License"). I know of another experienced instructor (specialising in vintage tailwheel planes) who swears by it

Their main rationale is that if you do get an engine failure, you will be used to the approach picture and handling characteristics of your aeroplane. There are also side benefits such as the better view.

What do people think?

Thanks
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Old 2nd Jul 2005, 18:10
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I understand this used to be standard practice.

Downside is that you complicate matters on a regular basis which is bound to end in tears more often. Also the safety angle must be marginal as properly operated idling/low power engines are not likely to fail?

My view is pracitce glides regularly, but not every approach.
 
Old 2nd Jul 2005, 18:28
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Used to be standard practice on rotary engined aircraft as they had no throttle. The only engine control was the mag switch.

I believe glider pilots do it quite regularly; not too many go-arounds.
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Old 2nd Jul 2005, 18:42
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I believe glider pilots do it quite regularly; not too many go-arounds.
Ah yes, but unlike me, a glider pilot probably has skill
 
Old 2nd Jul 2005, 18:56
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Coming from a microlight flying background, it's my personal standard practice as well - I have to remind myself from time to time to practice powered!

The benefits (in my opinion) are much as KCDW suggests, the main disadvantage is that in a crowded circuit it can confuse somebody behind you if they weren't expecting such a steep approach.

G
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Old 2nd Jul 2005, 18:57
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And speed brakes!
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Old 2nd Jul 2005, 19:55
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The disadvantage, to my mind, is that you have fewer options if you don't judge it quite right (e.g. if you didn't predict the sink on short final quite right).

If you get too high, you may have to side-slip or use an S-turn at low level, which isn't a problem, but it's much easier to just reduce the power a bit. If you get too low, you may have to add power, in which case it isn't a glide approach any more. Well worth doing from time to time, for practice, but not what I would consider a "normal" approach.

Does anyone have any statistics on how many "modern" piston engines suffer engine failure on the approach? I've never heard of it happening, and I'd guess that the statistics would be very very low. And in any case, most (but admitedly not all) approaches have some reasonable forced landing sites if the engine did quit.

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Old 2nd Jul 2005, 20:14
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Does anyone have any statistics on how many "modern" piston engines suffer engine failure on the approach? I've never heard of it happening, and I'd guess that the statistics would be very very low. And in any case, most (but admitedly not all) approaches have some reasonable forced landing sites if the engine did quit

There are lots of reports relating to things like - added power but engine failed to respond - carb ice suspected etc.

Also if one is gliding to a landing on the runway one does not have to considder forced landing sites.

One reason why one could be minded to complete a glide powered approach is that Mr Cessna uses that form of approach and the landing figures are based on that i.e. Power Off, Max Flap and Max Braking.

Oh, and the most efficient way to operate a jet is to remain at optimal cruise level until one can close the throttles and never open them again until on the runway.

Regards,

DFC
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Old 2nd Jul 2005, 20:39
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Try it in a seneca........
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Old 2nd Jul 2005, 21:04
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But at least you crash the right way up!


Re: glide approaches. I fly regularly from three different fields. One is full ATC, so glide approaches aren't really an option unless the circuit is clear. The second is a busy training field, where the C152s often seem to fly QXC circuits, so again only really an option if Number 1 and it isn't busy. Number three has gliders (part of the years), jets and piston warbirds - so again the circuit can be interesting, but it's possible on a quiet day in the week.

I agree that glide approaches are incredibly useful practice. Having done a few recently, I realised how out of practice I was. As someone who has also had an engine failure and forced landing a few months ago, I know from experience how a little more height could have made all the difference.

So, I would say glide approaches where possible, and more PFLs is probably the best practice to prepare you for the worst. Engines do stop when you least expect it!

RD
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Old 2nd Jul 2005, 21:44
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Thanks all so far. I'm beginning to get a picture.

Bose-x: Try it in a seneca........ Having not flown one, presumably the thing just falls out of the sky. In fact it makes me wonder about all the more powerful, heavier GA types which usually recommend a "trickle" of power just prior to landing. Surely we need that trickle of power to keep open the margin of safety for regular non-scary landings.

For the lighter GA types at "Radio" stations with an empty circuit. Then I guess the answer is "by all means".
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Old 2nd Jul 2005, 21:53
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It's an old fashioned idea which is pushed by the taildragger types mostly, and sometimes by people who can't fly the aircraft onto the ground.

Engine failure on short finals is generally down to icing, whch is more likely to occur with the throttle closed, and also power on the approach reduces the stall speed and helps tailplane authority.

Any approach is about energy management, and the easiest/best way to manage energy is with a throttle in your hand.

If you want to land in the right place, on speed, with the optimum rate of descent, use power on the approach. That's what it's there for.
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Old 2nd Jul 2005, 22:13
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Its horses for courses I think. I fly a 152 and a Seneca for quite a few hours per month on each aircraft. I regularily practice glide approaches in the 152 but my normal landing is power to the ground.

The Seneca which has the flying characteristics of a brick would be unlikely to achieve a glide approach from 5000ft in the overhead! Its probably the reason for the second engine!!

Like all things flying, use the tool for the job and don't get tied up in dogma.
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Old 2nd Jul 2005, 22:21
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If you want to land in the right place, on speed, with the optimum rate of descent, use power on the approach. That's what it's there for.
So how will you manage that on a forced landing?
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Old 2nd Jul 2005, 22:25
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Frank, See comment on horses for courses and give us less Dutch dogma!

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Old 2nd Jul 2005, 22:27
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Steve,

No dogma. It may be useful to be able to plant the thing on the numbers when you have not engine to smooth things out.

Would you not agree?
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Old 3rd Jul 2005, 00:37
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Went up on a check ride with an instructor in Wales who demonstrated the accuracy you can get from glide approaches. he cut the power late downwind, asked me to nominate one of the runway numbers, and without touching the throttle again, planted it directly on that number. I tried, but i think some more practice is needed on my part! I reckon practising any kind of emergency drill on a regular basis is essential, as it has already been said, things never scew up when its most convenient for you, so the whole boy scout thing is prudent i think.
JW
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Old 3rd Jul 2005, 08:47
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Every argument here for not doing glide approaches, is a perfect arguement for doing them.

The point about busy circuits is valid, but simply call "Short final for glide approach". It matters not if the field is ATC or A/G from a handheld.

As for some aircraft being unsuitable for glide approaches. This does not sit well with the fact that all aircraft are suitable for an engine failure.
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Old 3rd Jul 2005, 09:13
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Trouble is, everybody's right here. Yes, all aircraft are suitable for engine failure. And yes, some airfields are not suitable for glide approach, and you will not be thanked if you insist on doing them all the time.

Yes, engines fail, so good idea if your approach doesn't need one. And yes, engines are most likely to fail after running at idle, such as after a glide approach.

I compare the risk of an engine failure on a powered approach, with the risk that I might not make a perfect glide approach and need power at the end of it. No contest: the engine is probably more reliable than me, so I use power. Better pilots might decide otherwise. But I do practice glide approaches (and PFLs) regularly.
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Old 3rd Jul 2005, 09:32
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A downside that no one has mentioned is the possibility that repeated glide approaches, particularly in the full-power-climb/very-short-cruise/glide, do more harm to the engine than progressive power reduction. It's likely to be more of a factor for larger engines.

Whether that effect is big enough to swing the balance towards preferring powered approaches is, like everything else in engine-management-technique, difficult to provide quantitative evidence for.
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