Reducing flaps on short finals
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ST, you seemed to have no problem with some intelligent mixture and carb heat tinkering for the purpose of demonstration! I put a careful demonstration of the effect of flap on a glide approach in the same category. As far as I can see, there is no serious advocacy in any other context.
My stats for percentage full-flap landings in GA aircraft would be similar to yours.
The statistic changes slightly for very light aircraft in strong wind conditions.
My stats for percentage full-flap landings in GA aircraft would be similar to yours.
The statistic changes slightly for very light aircraft in strong wind conditions.
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Ah, but the difference is that tinkering with mixture to optimize the effect of carb heat has been demonstrated to produce quantifiable and desirable intended results toward an objective. And, any undesired affect can be instantly reversed. Not so with flap extension in some aircraft.
Tinkering with the flaps is evidence of a poorly executed approach, in why was that much flap extended so far back on final - it's just evidence of poor airmanship to find yourself in that situation. If you are flying a Twin Comanche, or Navajo, you'll probably get your knuckles wrapped by the check pilot if you start reducing flap extension on final approach, and certainly in any RG airplane you are increasing the risk of a gear up. ('Cause if you get the gear up, rather than some flap, the plane will feel somewhat similar).
On a checkride I once flew in a C310, I retracted the flaps on touchdown. The check pilot told me that he was going to fail my ride for doing that (inducing risk of gear up). I pointed out where it was a Flight Manual procedure for doing that in the 310. He grimaced and could not fail the check ride, but he still took points off.
For checkrides I fly, I would not sign off the pilot if they did, or thought they needed to retract flaps during a continued approach - more training.... = more $. On that same checkride, if the pilot demonstrated the understanding of the systems to know that leaning with carb heat might improve their situation, I would comment their systems knowledge, and broad thinking.
In a C 172, I cannot suggest that retracting the flaps on final is immanently life threatening, but it's an unnecessary and bad habit, which will have to be unlearned in "bigger" flying environments - so why start?
Tinkering with the flaps is evidence of a poorly executed approach, in why was that much flap extended so far back on final - it's just evidence of poor airmanship to find yourself in that situation. If you are flying a Twin Comanche, or Navajo, you'll probably get your knuckles wrapped by the check pilot if you start reducing flap extension on final approach, and certainly in any RG airplane you are increasing the risk of a gear up. ('Cause if you get the gear up, rather than some flap, the plane will feel somewhat similar).
On a checkride I once flew in a C310, I retracted the flaps on touchdown. The check pilot told me that he was going to fail my ride for doing that (inducing risk of gear up). I pointed out where it was a Flight Manual procedure for doing that in the 310. He grimaced and could not fail the check ride, but he still took points off.
For checkrides I fly, I would not sign off the pilot if they did, or thought they needed to retract flaps during a continued approach - more training.... = more $. On that same checkride, if the pilot demonstrated the understanding of the systems to know that leaning with carb heat might improve their situation, I would comment their systems knowledge, and broad thinking.
In a C 172, I cannot suggest that retracting the flaps on final is immanently life threatening, but it's an unnecessary and bad habit, which will have to be unlearned in "bigger" flying environments - so why start?
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ST, as I noted in the other thread, if a novice stops the engine during tinkering the results may not be so good. On your reasoning, why take the risk?
So far as changing the flap setting, you seem bent on ignoring the forced landing practice demonstration aspect in favour of an invented strawman standard practice which, as far as I can tell, no one is advocating.
So far as changing the flap setting, you seem bent on ignoring the forced landing practice demonstration aspect in favour of an invented strawman standard practice which, as far as I can tell, no one is advocating.
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Different planes are different.
And although some might think that not reducing flaps on final is an old wives tail, I know that in some planes the effects of doing so are drastically different than in other planes.
A couple examples, in a Maule, reducing the flaps will "drop" you onto the ground from as much as 10 feet up. Which can be nasty on the gear if you are that high. In a C 172, from 40 degrees to 30 degrees, there's not much but drag difference, so you tend to climb, but from 30 to 20 there's quite a bit of lift that's lost, and you don't climb, you descend. Which is why in a go-around you push throttles/mixture/heat first, and don't raise flaps until you have a positive rate of climb.
So, if you want to descend - either by losing lift, or by stalling - then put in flaps, slow to 1.2x the stall speed for that configuration and then reduce the flaps. Try that in your aeroplane, and see how much (if any) leeway you have. If you happen to be 1.1x stall speed for a configuration when you reduce the flaps, you may find that you need quite a bit of elevation to recover. This would be a good experiment for whatever you're flying.
Although, if you're going to do that experiment, be sure you have plenty of altitude before trying it.
And although some might think that not reducing flaps on final is an old wives tail, I know that in some planes the effects of doing so are drastically different than in other planes.
A couple examples, in a Maule, reducing the flaps will "drop" you onto the ground from as much as 10 feet up. Which can be nasty on the gear if you are that high. In a C 172, from 40 degrees to 30 degrees, there's not much but drag difference, so you tend to climb, but from 30 to 20 there's quite a bit of lift that's lost, and you don't climb, you descend. Which is why in a go-around you push throttles/mixture/heat first, and don't raise flaps until you have a positive rate of climb.
So, if you want to descend - either by losing lift, or by stalling - then put in flaps, slow to 1.2x the stall speed for that configuration and then reduce the flaps. Try that in your aeroplane, and see how much (if any) leeway you have. If you happen to be 1.1x stall speed for a configuration when you reduce the flaps, you may find that you need quite a bit of elevation to recover. This would be a good experiment for whatever you're flying.
Although, if you're going to do that experiment, be sure you have plenty of altitude before trying it.
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Let me ask you a question? Why would you need to pull the last 3rd notch of flap at all or at minimum till your 50 to 100 feet and assured of landing ?
The only time I can think of is if you are high, need the drag to fly a steep profile onto the runway landing spot.
The only time I can think of is if you are high, need the drag to fly a steep profile onto the runway landing spot.
The session of circuits i mentioned in Feb where it was BLOODY HOT was a good case in point.
(Under the bubble canopy in the Sporty is like being locked in a car in full sun
) I was flying the roughly the same circuit track across the ground as i'd done previously but we just weren't coming down, so at least initially we needed full flap. After a couple of circuits we could make those adjustments extend downwind which allowed a greater distance traveled to lose the same height.
But the hot weather and thermals still caught us out, one approach that stands out i decided not to go to full flap but consequently we arrived at the threshold a shade too fast and so i got some extra practice holding off as we floated an extra 100m down the runway - still landed with plenty to spare but the difference was obvious.
The more experienced operator than myself could possibly anticipate those conditions adjust to the situation accordingly and get it spot on first shot.
Hence
achieving proficiency in any skill which increases your options should you find yourself in such a situation will, IMO, only improve safety.
In that sense it's not my best flying that i'm trying to improve, but my worst
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Step Turn
In a C 172, I cannot suggest that retracting the flaps on final is immanently life threatening, but it's an unnecessary and bad habit, which will have to be unlearned in "bigger" flying environments - so why start?
In a C 172, I cannot suggest that retracting the flaps on final is immanently life threatening, but it's an unnecessary and bad habit, which will have to be unlearned in "bigger" flying environments - so why start?
I wonder if the OP or anyone else has considered that maybe this pilot was just practising a glide approach after simulating an engine failure downwind, that would make the above procedure a perfectly normal technique to obtain the correct touchdown point on your runway, or an off airport landing in a field
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Ah, but the difference is that tinkering with mixture to optimize the effect of carb heat has been demonstrated to produce quantifiable and desirable intended results toward an objective. And, any undesired affect can be instantly reversed. Not so with flap extension in some aircraft.
And your point of "quantifiable and desirable intended results toward an objective" is cobblers. The OP observed that the reduction in flap had the desired result. It is truly absurd to wave that observation away with rhetoric, whilst simultaneously clinging to the belief that reducing engine power is a good antidote for carb icing!
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I say how I fly, I fly as I say. I'll read what people post, and consider it. I'm not persuaded about retracting flaps on final, so I still won't. I've never need to, why start now?
I'm not an instructor, I'm not checking you out, my advice is free here, so you're getting your money's worth. Fly as safely as you can figure out how, and fly as you would have someone else fly your loved ones in their plane....
I do.
I'm not an instructor, I'm not checking you out, my advice is free here, so you're getting your money's worth. Fly as safely as you can figure out how, and fly as you would have someone else fly your loved ones in their plane....
I do.
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You could say the same about any form of emergency training.
You hope you'll never need to do it in anger, but it's reassuring to know you have an additional skill if the worst happens. It's as much about confidence as ability.
There's a trade off between the additional risk of training, and the potential benefit of this training in an emergency situation.
Many aircraft have been lost in training accidents, and I think the balance is shifting. I suspect a PPL course today would be more oriented toward safety than when I learned to fly in the '80's.
You hope you'll never need to do it in anger, but it's reassuring to know you have an additional skill if the worst happens. It's as much about confidence as ability.
There's a trade off between the additional risk of training, and the potential benefit of this training in an emergency situation.
Many aircraft have been lost in training accidents, and I think the balance is shifting. I suspect a PPL course today would be more oriented toward safety than when I learned to fly in the '80's.
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This is going round and round in circles 
Think energy management airframe and engine.
Going downhill
We are tapping into the potential energy in the airframe as well as from the engine meaning the aircraft will accelerate! steepen that approach and it will accelerate even further.
I always like to think of two throttles the engine one and the elevator so we are managing energy.
We also have various chunks of drag we can tap into airframe, flaps. gear, speed brakes props (esp VP) so we are also tapping into that lot.
Flaps give us lift as well as drag enabling us to land at slower speed.
Going down hill where we are using the potential energy in the airframe means that normally we will use drag to help us slow to a VREF speed by adding chunks of drag on our way down.
going down hill why would we want to remove drag unless we are wanting to go uphill again?
If we loose the engine we now have only one source of energy on a still day from the airframe!
We no longer have an energy source from the engine so trying to fly as far as possible while using as little energy from the airframe means we need to be as clean as possible.
Add drag and we have to use the airframe throttle i.e. the control column by pitching down to get enough energy to combat that drag. Pitching down gives us the energy but looses altitude.
Engine out we should only add drag when we are assured of a landing and sure of the glide path that drag has given.
Get that glide path wrong and the only way to extend the glide to reach a landing spot is to remove the drag or pick another landing spot on our descent profile.
But that is extreme! Normally going downhill add drag in a stabilised approach don't remove it ? Sorry if this is simplistic its not directed at our more advanced posters here
In the Citation if I want a steep descent rate or need to control speed pop the speed brakes (another form of useable drag) If my thrust levers are at idle or I need some thrust for engine anti ice . Levelling I will pop them away again think energy management
I suppose the ultimate drag is in the cirrus which gently lowers the aircraft to the ground under the caps
Pace
Think energy management airframe and engine.Going downhill
We are tapping into the potential energy in the airframe as well as from the engine meaning the aircraft will accelerate! steepen that approach and it will accelerate even further.I always like to think of two throttles the engine one and the elevator so we are managing energy.
We also have various chunks of drag we can tap into airframe, flaps. gear, speed brakes props (esp VP) so we are also tapping into that lot.
Flaps give us lift as well as drag enabling us to land at slower speed.
Going down hill where we are using the potential energy in the airframe means that normally we will use drag to help us slow to a VREF speed by adding chunks of drag on our way down.
going down hill why would we want to remove drag unless we are wanting to go uphill again?
If we loose the engine we now have only one source of energy on a still day from the airframe!
We no longer have an energy source from the engine so trying to fly as far as possible while using as little energy from the airframe means we need to be as clean as possible.
Add drag and we have to use the airframe throttle i.e. the control column by pitching down to get enough energy to combat that drag. Pitching down gives us the energy but looses altitude.
Engine out we should only add drag when we are assured of a landing and sure of the glide path that drag has given.
Get that glide path wrong and the only way to extend the glide to reach a landing spot is to remove the drag or pick another landing spot on our descent profile.
But that is extreme! Normally going downhill add drag in a stabilised approach don't remove it ? Sorry if this is simplistic its not directed at our more advanced posters here
In the Citation if I want a steep descent rate or need to control speed pop the speed brakes (another form of useable drag) If my thrust levers are at idle or I need some thrust for engine anti ice . Levelling I will pop them away again think energy management
I suppose the ultimate drag is in the cirrus which gently lowers the aircraft to the ground under the caps
Pace
Last edited by Pace; 15th May 2015 at 10:38.
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Quote:
Originally Posted by Step Turn
I've never need to, why start now?
You could say the same about any form of emergency training.
Originally Posted by Step Turn
I've never need to, why start now?
You could say the same about any form of emergency training.
Nothing in 39 years of flying had told me that retracting flaps for a continued landing is a formal emergency procedure, why would I train for it?I regularly practice formalized emergency procedures, as each pilot should...
I do not extend flaps before I need them, and their extension is appropriate to the continued approach to landing, so it's never been a problem to have to consider retracting them!
I have had an asymmetric flaps failure in a Cessna 180 floatplane, while on the step, in a remote lake, and that was eye opening. I'm heartily glad I was not retracting them down final approach when it happened!
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Not just if you've misjudged a glide approach. It's possible to lose all engine power after configuring for landing. Certainly unusual, but it has happened.
Think BA38.
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Sillert
It is important to think out of the box about energy management and there will be occasions when having got it wrong you need to eliminate drag.I would get rid of gear first even though it meant putting gear down again if in a retractable.
Twin pilots tend to be more drag aware for obvious reasons
But this isn't the point the OP is a student who thinks he can use the last stage of flap as some sort of air brake ? WRONG
Thinking out of the box comes with experience which students do not have and to teach such use of flaps when the instructor would be better teaching how not to be in such a situation is more important
having to retract flap means you have added it too soon so why not concentrate on flying a stabilised approach and energy management and teach students when to add full flap instead of them dragging in with full flap from five miles out! Also teach the glide profile with each stage of flap
Get the fundamentals right especially with students and start to teach them energy management.
when I read the rubbish posted about pitch for speed or power
I really wonder what students are being taught. Its energy management which is poorly taught and then there would be no need to retract flaps to correct an error?
Step turn is correct overall and I am sure thinks energy management
It is important to think out of the box about energy management and there will be occasions when having got it wrong you need to eliminate drag.I would get rid of gear first even though it meant putting gear down again if in a retractable.
Twin pilots tend to be more drag aware for obvious reasons
But this isn't the point the OP is a student who thinks he can use the last stage of flap as some sort of air brake ? WRONG
Thinking out of the box comes with experience which students do not have and to teach such use of flaps when the instructor would be better teaching how not to be in such a situation is more important
having to retract flap means you have added it too soon so why not concentrate on flying a stabilised approach and energy management and teach students when to add full flap instead of them dragging in with full flap from five miles out! Also teach the glide profile with each stage of flap
Get the fundamentals right especially with students and start to teach them energy management.
when I read the rubbish posted about pitch for speed or power
I really wonder what students are being taught. Its energy management which is poorly taught and then there would be no need to retract flaps to correct an error?Step turn is correct overall and I am sure thinks energy management
Last edited by Pace; 15th May 2015 at 12:08.
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Because it might one day save your life.
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Step Turn
So what you are saying is you never get anything wrong or never mis judge anything, and if you are performing an emergency landing due to engine failure that once you have committed to a field and lowered flaps then realised the approach is not working out correctly you would just continue regardless even if by raising some flap that extended the glide to land safely just because it is not written in a manual.
This sounds as blinkered as the Swissair Flight 111 where the crew refused to deviate from completing the SOP for fuel dumping but where happy to burn up in flight and crash.
So what you are saying is you never get anything wrong or never mis judge anything, and if you are performing an emergency landing due to engine failure that once you have committed to a field and lowered flaps then realised the approach is not working out correctly you would just continue regardless even if by raising some flap that extended the glide to land safely just because it is not written in a manual.
This sounds as blinkered as the Swissair Flight 111 where the crew refused to deviate from completing the SOP for fuel dumping but where happy to burn up in flight and crash.
Last edited by Above The Clouds; 15th May 2015 at 12:33.
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Quote:
Originally Posted by Step Turn View Post
Nothing in 39 years of flying had told me that retracting flaps for a continued landing is a formal emergency procedure, why would I train for it?
Because it might one day save your life.
Not just if you've misjudged a glide approach. It's possible to lose all engine power after configuring for landing. Certainly unusual, but it has happened.
Think BA38.
Originally Posted by Step Turn View Post
Nothing in 39 years of flying had told me that retracting flaps for a continued landing is a formal emergency procedure, why would I train for it?
Because it might one day save your life.
Not just if you've misjudged a glide approach. It's possible to lose all engine power after configuring for landing. Certainly unusual, but it has happened.
Think BA38.
If I lose my engine after configured for landing, then I will, well, um, land.
I shouldn't have to change anything in the configuration of the aeroplane to accomplish the landing.
If I'm landing in such a way that I require an engine to land, then I'm descending on too low of a glide slope.
Once I've committed to landing, the only thing I should need the engine for is a go-around.
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So what you are saying is you never get anything wrong or never mis judge an anything,
if you are performing an emergency landing due to engine failure that once you have committed to a field and lowered flaps then realised the approach is not working out correctly you would just continue regardless even if by raising some flap that extended the glide to land safely just because it is not written in a manual
I recall that Genghis kindly provided an authoritative reference earlier in this thread, that the modulation of the flaps in the BA 777 LHR crash was not determined to be beneficial, but I do not have first hand knowledge of this event, nor flying 777's. But, I don't accept that event as persuasive that modulation of flaps is a good idea for normal operation.
This thread has an air of suggesting that pilots should be innovative. I can't argue innovative thinking, but I feel that pilots should be innovative within the conventional training, and aircraft operating norms. You can always cite rare extreme situations which demonstrate out of the box thinking, and isn't that nice, but those situations are a long way from a public forum directed toward GA pilots of average skill and experience. I think of the Sioux City Iowa DC-10, we're just not doing that stuff in 172's.
If a pilot does something innovative, which saves lives and property, pat them on the back for a job well done. But be very careful of adding that new technique to the norm, for everyone to include in their day to day flying - that's a huge stretch. We still have the occasional convenience store owner who stands up to a robber and succeeds. But we will always have the authorities say afterwords that the safer thing to do is to hand over the money, and not take risks. If the engine quits, it's safer to follow established techniques to maintain a stabilized - non distracted glide, to a suitable site. The final approach stage of a gliding forced landing in a 172 is NOT the time and place for a GA pilot to start innovating - focus on the task.
So you won't see me on here promoting an unestablished technique which can take the user toward real risk. Modulating the flaps of a 172 500 feet up on approach is not risky, I agree with that - it's just sloppy and needless technique. But modulating the flaps in the same way at 50 feet up will be very dangerous.
In light of the constant complaints about the cost of certified aircraft, do people seriously want the effort expended to test and approve this procedure, and define in pages of data, reports, and flight manual procedures when it may be applied, how, and when it is not safe to do? It's much more cost effective to not endorse it at all - because good flying technique will never call upon it - and keep things more simple.
A C152 aerobat has removable doors. Would you just take them off on a nice day for that breezy feeling while flying? Or would you seek out a two door off approval (which does not exist) to allow that aircraft to be flown with both doors off? Fly the plane in the established configuration.... Or, pay the flight test costs to gather the data to define how the new procedure/configuration might be safely flown. I have approved my 150 to fly with either door off - I innovated, and I paid the approval cost for that.
