To use a glide approach or not.

[farri]

Here is at least one good reason to maintain a glide approach when on final.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

 

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This happened quite a while ago but the principal still applies today.<o:p></o:p>

 

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Just a reminder of what can happen when the engine decides to stop at the wrong time and place.<o:p></o:p>

 

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About two weeks after I`d test flown this aircraft for the new owner, this happened.<o:p></o:p>

 

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He was doing circuits at another private strip in our area, when on final approach, he idled the engine back and it stopped, He could have glided to the strip quite easily had he adopted a good glide approach , he ended up only about 100 metres short of the field.<o:p></o:p>

 

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He came down in the tall sugar cane, just clearing a drainage channel, about 2 metres deep by 2.5 metres wide, the tail was resting just 1/ 2 a metre past the bank and had he hit the bank with the nose, it may well have been fatal.<o:p></o:p>

 

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That`s me with the white cap and blue jeans and the guy holding the prop is another local Drifter driver …….the guy kneeling is the owner pilot ……..we`re all much older now of course.<o:p></o:p>

 

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Cheers,<o:p></o:p>

 

Frank.<o:p></o:p>

 

 

 

 

[Guest basscheffers]

Did he have flaps out? If you have flaps out and the engine quits, the first reaction should be to put them away and go to 0-flap best glide speed.

 

That's a rule in pretty much any aircraft. Even the BA 777 that crashed short of the runway at Heathrow wouldn't even have made it over the boundary if the captain had not retracted some of the flaps. (unfortunately, this is not in their drills as they don't practice all engines out. If they had, he would have done it immediately and the aircraft probably would have made the runway.)

 

 

[Spin]

cficare I agree up to a point, although I did conduct an impromptu experiment during my RA conversion. After being pulled up a few times for underestimating the glide performance of the Tecnam on PFL's, the inevitable happened and I ended up with a powerline bisecting my aiming point during the next one. In a real failure I would have considered ducking under, but suspected that wouldn't go down well with he who inhabited the rhs, so I reduced flap from full to t/off setting and low and behold the wires promptly dropped down the windscreen and I cleared them safely, reapplying full flap as I went overhead. Given that I was already in a glide, dumping drag flap to a reduced, mostly lift setting didn't give any discernable increase in sink rate, even momentarily.

 

 

[Guest basscheffers]

reckon i'd like to check out the "improvment" to glide performance achieved by deselecting and going to zero flap on finals (assuming below 500'agl)...a little late to start throwing lift away..

You are putting away a lot more drag than you are throwing away lift.

The published best glide in my aircraft is 0-flap and 57kt. Obviously, a normal approach at 60kt and full flap is going to make you fall short.

 

Once set up in that configuration, I need the engine all the way to the flare. If the engine stops, I will not make it; laws of physics and all...

 

Best glide configuration and speed is the best option in my opinion.

 

And I have tried, at altitude, gliding in different configurations. The SportStar with full flaps on does not glide very far ... at all! :)

 

 

[pylon500]

Did he have flaps out?

UM, did you happen to have a look at the attachment?

 

The aircraft is so basic, it's not likely to have flaps, possibly doesn't even have ailerons (uses secondary rudder)

 

Remember, on most aircraft, FULL flap is more for drag than low speed lift.

 

As for the SportStar, you need to remember it doesn't have flaps, just a big split airbrake, probably a good idea to close that if the motor stops!

 

Arthur.

 

 

[Teckair]

Glide approaches are best for several reasons, unfortunately many pilots don,t want to do them because it takes more skill to judge a power off approach than regulating your height by using the throttle.

 

Best way is to aim to be slightly high and then slip the spare height off when you are sure you will make the strip.

 

Doing it this way means you should make the strip if your motor stops on final and you are practicing a emergency landing every flight.

 

Since I started flying I have had quite a few engine failures and every time I can thank glide approaches for saving my backside.

 

 

[Teckair]

I can also confirm that raising the flaps on certain aircraft will extend the glide if you are going to be short of the strip.

 

 

[facthunter]

depends on aircraft.

 

The Technam has a lot of drag with full flap, and how much do you have to increase your speed? 8 knots? ( I'm guessing but something like that.) so do it.

 

IF you are talking commercial Jet transports from approach flap to minimum clean speed is about 85 knots. Forget it with engine out at low alt.. Partial retraction might help a little but I reckon under 600 feet you are in strife. Jets approach normally with a fair bit of power on so there is a big deficit of energy when the donks go quiet.. Nev

 

 

[farri]

The aircraft is so basic, it's not likely to have flaps, possibly doesn't even have ailerons (uses secondary rudder)Arthur.

No it didn`t have flaps and yes it did have ailerons.

 

There are still plenty of basic aircraft out there but this shouldn`t determine how the pilot chooses to peform a final approach.

 

Frank.

 

 

 

[Guest basscheffers]

IF you are talking commercial Jet transports from approach flap to minimum clean speed is about 85 knots. Forget it with engine out at low alt.. Partial retraction might help a little but I reckon under 600 feet you are in strife. Jets approach normally with a fair bit of power on so there is a big deficit of energy when the donks go quiet..

Well, in the captain's own words, the partial retraction helped quite a bit in this case.

Putting them away completely might not be a great idea, but a quicker reaction on the partial retract would have got them even closer - possibly on the runway. They were really, really close as it was; the nose came to rest on the threshold after all.

 

 

[biggles5128]

You tend to hear of much more engine stops when pilots suddenly pull the power back to idle rather than maintaing some power. The aircraft has performed very well for the flight and then we want to glide it in...... For my money, I like to maintain a powered approach with less liklihood that the engine will quit.

 

 

[farri]

I have no problems with glide approaches,I regularly do dead stick landings,therefore, my glide needs to be completely accurate.

 

With a normal approach my prefered method is to turn final with sufficient hight that I can make it safely,no matter what,then slip off any excess height at the appropiate time.

 

I always keep the correct amount of power on,to allow for wind shear and safeguard against engine failure or a needed go around,at times,due to wind conditions,I will power onto the strip.

 

Frank.

 

 

[facthunter]

Heavy's flaps.

 

Bass, I reckon above 1000', (hard to be precise) you would reduce flap from the Max. Not ALL landings use the Max flap. Usually there is a weight limit, above which you can't use it. When the flap is are retracted there is always a substantial loss of lift and the nose has to be rotated to compensate. This is not instantaneous, so you tend to lose a bit of height. nev

 

 

[kaz3g]

...raising the flaps on certain aircraft will extend the glide if you are going to be short of the strip.

 

Yes... But lower the nose and restablish best glide speed for the new configuration.

 

kaz

 

 

[Guest basscheffers]

Yes... But lower the nose and restablish best glide speed for the new configuration.

On the SportStar? Have you seen the attitude it takes with full flaps? I think I'll raise the nose to get to best glide speed with no flaps, thank you very much. :big_grin:

In fact, I reckon that will be what you would do in any aircraft: engine quits, push nose down to maintain airspeed while you have the drag of the flaps. Then you get rid of the flaps and you will likely have to raise the nose to get your best glide speed.

 

Of course make sure that if you have let the airspeed drop, get the airspeed you need back by lowering the nose and then get rid flaps. Getting rid of full flaps at 40kt probably isn't the best of ideas...

 

 

[kaz3g]

"On the SportStar? Have you seen the attitude it takes with full flaps? I think I'll raise the nose to get to best glide speed with no flaps, thank you very much"

 

I was checked a few years ago in a Sportstar at Parafield but I honestly don't remember any huge attitude change with flaps such as you get in a C172 with 40 degrees.

 

I guess it might depend on the inertia of your particular aircraft, the L/D ratio, the difference in stall or best glide speeds between flapless and full flap and especially whether there is still some noise going on outfront?

 

On a light note, I had a look at an old logbook and discovered I have done around 750 deadstick - no noise at all - landings.... in gliders. Only one in power and not a voluntary exercise.

 

GA currently tends to teach powered approaches and has done for many years now. I did some practice FL in a C172 with an instructor friend a while back and she asked me to abandon my space-shuttle manouvres because she didn't like staring at the ground instead of the horizon. She did admit, however, I would be in a better situation than most if things went s..tful in the circuit.

 

kaz

 

 

[Tomo]

I did some practice FL in a C172 with an instructor friend a while back and she asked me to abandon my space-shuttle manouvres because she didn't like staring at the ground instead of the horizon. She did admit, however, I would be in a better situation than most if things went s..tful in the circuit. kaz

Almost the exact same words have been used on me!

 

Me and my steep glide approaches with 40 flap, and whoops, powers on idle... :black_eye: He told me I handle it very well, but please don't do that sort of thing for a normal approach.

 

 

[Guest basscheffers]

I was checked a few years ago in a Sportstar at Parafield but I honestly don't remember any huge attitude change with flaps such as you get in a C172 with 40 degrees.

I have 160 hours now in that particular SportStar, I own it. :)

Maybe you never went beyond the second stage (30 degrees, I believe) of flaps? With the full 50 degrees and a low power setting, it feels like you are pointing straight down.

 

Practicing a flapless approach ay 70kt is much, much less nose down. Best glide at 57kt would of course have an even higher nose attitude.

 

especially whether there is still some noise going on outfront?

The discussion here was about losing the noise on final. :)

 

 

[Mazda]

Round in circles again. Glide approaches are not the best, otherwise professional airline and military crews would do them every day. But they don't.

 

Powered approaches are normal in a powered aircraft. Glide approaches either mean you are in a glider, are practising an emergency procedure, or you've stuffed up and going to idle power and slipping the thing in is your only way of getting down. It removes your options.

 

But the worst thing is it is really hard on engines. By doing glide approaches all the time, especially in circuits, you might find you can't increase power when you want, and the engine might have shock cooling issues.

 

It's ironic that in trying to fly in a way to safeguard from engine failures may make an engine failure more likely.

 

 

[Guest basscheffers]

Round in circles again. Glide approaches are not the best, otherwise professional airline and military crews would do them every day. But they don't.

Yup, that is why I fly an approach with power on (around 3000-3500 rpm on the Rotax) which gives me an angle where I *could* glide if the fan failed and I put the flaps away.

Best of both worlds in my mind. I don't like full glides for the reasons you explained and I don't like a shallow approach either as you don't have a second option when the noise stops.

 

 

[Yenn]

I would disagree with the increased likelihood of an engine failure with a glide approach. Reduce power on downwind or earlier and there should be no problem.

 

Just thinking back to the news part of this website, I can remember several GA planes landing short of the strip when the engine stopped and the funny thing is that they keep doing it. I can't remember an accident during a glide approach. The shallow approach is the one favoured by a lot of GA pilots and it frightens me to see them low and slow, with nowhere safe to go if it coughs. They do that even if there is a long strip and it has a vertical face at the threshold. As does Old Station.

 

 

[dazza 38]

This is interesting, when learning to fly, in a drifter, i was taught and always did glide approaches.When i did Ga, and modern RAA A/c,eg- 912 powered, i used and still use power approaches.With glide approaches every now and again.In a 912 powered a/c, i dont have a problem doing powered approaches as they are reliable, the chances of failing, on final after just flying for a hour or so, is pretty slim.But i was taught in the 2 stroke drifter to do glide approaches, because 2 strokes less reliable.Best to make sure you can reach the strip easliy and slip if needed, instead of using a powered approach and have the engine bog down or fail .Im not saying either way IMO is right or wrong.This is what i have been taught.Im wondering how many other people have been taught the same way?

 

 

[farri]

It is not absolutely correct that you will coke up spark plugs in a 2 stroke simply by doing glide approaches.

 

I put a lot of time and effort into teaching how to walk away from an engine failure and because I had the benefit of using my own strip,I would pull the power off from various points and height, relative to the strip and bring the student all the way to a full stop on the strip,never once did I foul a plug,we would simply warm the engine up and go again,I`m not saying that it can`t happen though.

 

I have been reading our monthly mag for a very long time and I`ve seen how many engine failures that there have been and it`s been 2 and 4 stroke and they continue to happen.

 

To my knowledge there`s no regulation that states, that when on final, you must be able to reach the runway in the event of engine failure,but who in their right mind is going to depend on the engine to drag them in because they are too low.

 

A true story........if the guy I`m talking about reads it,"Please understand I`ve only writen this to make the point".

 

A guy was flying into my strip and was about half a nautical mile away when I looked up and saw him, he was coming in, in level flight at a height that there was no chance at all of making the strip should something go wrong.

 

At that time there was a single row of trees at one end of the strip between the neighbour and I and the AC was coming in from that end, unfortunately there was a storm front approaching and it got quite windy, when he got about 200 metres from the strip, I estimated his height to be about 100`AGL, all of a sudden he hit some nasty turbulence and lost a fair bit of height, he later claimed that he also had engine trouble.

 

He kept coming in and realised that he wasn`t going to clear the trees and at the very last minute he did a very tight turn to the right,to avoid the trees and simply hit the ground with the right wing followed by the rest of the AC,a total rebuild job,to see it happen I thought it would be fatal,he hardly go a scratch and it probably was better than hitting the trees,who knows?

 

Bottom line.......Once he got to final approach, he should have been at a height to be able to make the strip,no matter what.

 

Frank.

 

Ps, Wasn`t one of my students.

 

 

[Guest Dick Gower]

For instructors, there is another good reason for ensuring that students can do a glide approach: some pilots can not flair from the steeper glide approach and have been getting away with submarine approaches for years.

 

At big airports the problem is not easily detected in a check but at a small country airport over an obstacle it is a different story.

 

If the only glide approach a student ever does is in a PFL where there is no subsequent landing, the problem is never detected.

 

 

[JG3]

...want to cokeup the spark plugs on the 2stroke?...use a glide approach..(judge it well cos u probably wont get much result when u open the throttle)

Not so in my experience. I did thousands of idle power glide approach touch-and- goes in the 1000 hrs that I flew a Rotax 447. Never a problem.

 

JG