Teaching the Glide Approach in elementary training aircraft.

[Centaurus]

There are several schools of thought on teaching the glide approach in elementary training aircraft such as the C172, Warrior et al. One technique is to cut the throttle just before base and treat it as a forced landing without power. This has the disadvantage of cutting off aircraft ahead of you as the aim of the exercise is lost if you cannot get an unobstructed glide.

The second technique is to turn base normally then when in level flight on base and a comfortable glide can be made, simply close the throttle and take it from there. If an undershoot becomes apparent, open the power to level flight and after intercepting the glide angle, cut the power and glide in. This latter technique has the advantage of being able to accommodate other circuit traffic.

For example, if you are on extended downwind due traffic ahead, you delay throttle closure until either turning final or even on final while holding level flight. In all cases the aim of the exercise is to become competent at judging the glide angle and enables this judgement to be later applied to a forced landing without power. Your suggestions as to which method you have been taught during your elementary flying training would be greatly appreciated.

Finally, if full flap has been used during the glide approach on final and it becomes apparent an undershoot is occurring then clearly you are in potentially serious trouble. Depending on the aircraft type then it may be necessary to retract the flaps to a new setting to reduce the drag with extended flap. This should only be considered if the margin between stalling speed with flaps up and flaps down is typically 5 to 7 knots and the airspeed is appropriate at the time. It can make all the difference between landing short of the field or just getting in.

Again, your comments would be appreciated. Remember the old saying "there are many ways to skin a cat", and it is important as an instructor not to be pedantic when it comes to differing ways of flying an aeroplane.

[Say again s l o w l y]

I personally like to keep the position on the throttle chop in the same place, i.e. abeam the threshold at 1500'. (or Low key if you like.)

This allows the student to see how their actions can make a difference. If you constantly vary the start position, then it is not a repeatable excercise.

This is one occasion when I say stuff the other traffic and do it when the circuit is quiet. Easier said than done, but the benefits in my eyes out weigh the problems.

[7FF]

I agree with 'Say again s l o w l y'. Using power to adjust a glide approach rather defeats the object of the exercise. The reason for practicing a glide approach is training for the day when it becomes a reality. Then at least the picture is familiar when the brain falls out of the sitting regions after an engine failure. However, once the glide approach has been mastered then positioning for the glide approach can be altered using power. Why not simply adjust your position in the circuit pattern to accommodate the glide from 'low key'. We used to make known our intentions for a glide circuit before turning upwind so that others in the pattern can adjust their circuits as well. Undershooting/overshooting is adjusted by altering the finals AOB. That's why you should not pick a landing spot straight ahead. Full flap should only be used when landing is assured. Initial ballooning on selection of full flap has on one occasion that I know of, enabled the clearance of a hedge.

[Rosanna]

I have different parameters for single engine (i.e. C152 - PA28 - TB9) 1500' high key - 800' low key - 400' final.
I let the studend decide where cut off throttle in downwind leg so he/she can find him/herself the best position from which with the best glide he/she can land in runway safety.

[BEagle]

The only real way to fly a glide approach is to close the throttle at a position from which a power-off approach can be flown all the way to touchdown. Anything else is rather a fraud.

I'd prefer to do so from 'low key' at 1500ft as 'Say again s l o w l y' describes. But at other aerodromes which require rectangular circuits at 1000ft, it has to be somewhere on base leg.

What is the prupose of a glide approach? As far as Im concerned, it's to learn the final part of a forced landing without power.

[EGBKFLYER]

What BEagle states is what I was taught initially and on the FI course.

[cleggs]

I like to teach that it is desirable not to get further than gliding distance from the airfield when flying curcuits. At least if they suffer an engine failure they have a chance at a safe landing rather than ending up in a factory roof, even if it's not on the runway.

Generally with glide approaches I try to do them when we are number one in the circuit. I pull the power on late downwind (at 1000 ft) and get them to use their track (ie, cut in or extend) and flap make it in safely. Most manage quite well once they realise they need to start a turn towards the rwy straight away. I get them to aim for a point about 1/3 of the way down the rwy. That way, if its all going well, bringing on flaps will bring their touchdown point back towards the threshold. If not, they can delay the flaps and still have a chance of getting it onto the rwy.

[homeguard]

While the benefits of teaching the Glide Approach will also aid the pilot in ensuring a safe forced landing the primary purpose is to teach the student to approach and land without power.
Some aircraft are much better to approach circling while gliding from say abeam the threshold. I hate a straight approach under power in say a Pitts which from a circling steep glide handles much better, allows side slipping and gives me a good forward view of the runway until the hold off. A glide technique will also be beneficial at many non licenced strips when a steep approach inside of obstructions such as power lines, rising ground and tall trees are a factor. Excersise 13 glide approaches are first and formost to teach the student to approach steeply without power and to use flap appropiately when available. Such a skill learned will of course be applied when training for forced landings.

[Whopity]

"Finally, if full flap has been used during the glide approach on final and it becomes apparent an undershoot is occurring then clearly you are in potentially serious trouble"

On a glide approach flap is used to bring the aiming point towards you therefore, it should not be selected untill you are guaranteed to make the aiming point without it! i.e. at 400 feet on Final.

The whole point of practicing the glide is to learn to assess the vertical angle between yourself and the aiming point and then to maintain that angle. Once established on final you can use flap to steepen the approach and bring the aiming point towards the aircraft. f you can't achieve that, then practicing long straight in glide approaches is both a wate of time and at worst likely to teach low houred pilots an inappropriate technique.

[Centaurus]

Teaching glide approaches. Seems awfully complicated this business of flying 1500 ft circuits, darting in from downwind, and teaching a forced landing from downwind. Wouldn't it be simpler to practice glide approaches like they used to in the good old days without all the hassle? After all, all you have to do is turn base normally - maintain circuit height (1000 ft) on base - judge the wind - then when you are in a position to glide in, simply close the throttle and Bob's your uncle.

The aim is to teach basic glide judgement with the minimum of fuss. Just because this technique was taught in flying training establishments military and civil both before WW2 and after, doesn't mean it is Jurassic flying. Later, when the student has demonstrated competency at this technique, then by all means get him to carry out a practice forced landing from downwind if you wish.

[Say again s l o w l y]

Personally I find it easier to judge glides from a curved approach rather than a straight one.

I am also teaching someone to manoeuver an a/c into a safe landing following an engine failure, not to be simply able to judge when to close the throttle to ensure you can arrive at the right point.

By fixing the position of the simultaed failure, you are able to demonstrate how different conditions and techniques affect the glide performance, this allows the student a datum to be able work out how to successfully get the machine to go where they want without power.
That is the best method I know of teaching glide judgement.

That is the most important thing, not how complex the FI percieves the manouever. Fitting in with traffic can be a problem, but it is minor compared to the benefits.

[BigEndBob]

I also use the glide approach as a means of landing if i get a stuck throttle.
Simulate a stuck throttle and student then has to judge when to chop the power (mixture in real situation), gives a slightly different slant on the subject rather than keep going on about pfl practise. I make sure i have covered this pre solo.

[7FF]

But it is still a PFL in the end.
For a stuck throttle you could also try max rate turning on finals to lose the speed and height. Lower the gear and flaps as the speed washes off, then when over the threshold and lined up, cut the power and go for it. Provided you havn't blacked out or throwing up too much by then.:E

[BEagle]

How many people have ever experienced the mythical 'stuck throttle' situation?

Are there any instances on record over the last, say, 20 years?

[7FF]

Stuck throttle:
Only ones I know of were a hawk in the early eighties and a 'thrust lever' on a 747 in the late ninties.

[scroogee]

regarding BEagles question, it happens- while in my early stages I witnessed a student land with 1800 rpm in a c152 (not by choice). He used flap, and carb heat to fly the initial approach to the ground (long runway) then mixture to stop the aircraft.

And while not quite the same I had a throttle linkage fail (un bolt) on a C337, resulting in the rear engine "stuck" at 75%. In my case I went around. flew the circuit on that engine with gear and flap extended and the other engine at idle, then once assured of a landing I shut down the 75% with the mixture and used the other engine to make a normal landing. Turns out someone had not used nyloc nuts where they should have.

[TheOddOne]

We had the throttle stick on our Rallye many years ago - the bell-crank joining the two throttles had been mis-assembled following a check. Resulted in a field landing outside the aerodrome boundary. A/c was successfully flown out again the next day after repairs.

Cheers,
TheOddOne

[Centaurus]

I have not flown ultra-lights but does ultra-light training include glide approaches or are they all dragged in final approaches with lots of power and howling props like normal Cessna approaches?

[Dr Eckener]

What is the prupose of a glide approach? As far as Im concerned, it's to learn the final part of a forced landing without power.
Totally agree with this beagle. Amazing that we agree on something!

I like to teach that it is desirable not to get further than gliding distance from the airfield when flying curcuits
That means that you can never fly a powered approach.