Question For The Experts - Use Of Flaps.

[Sunfish]

Flying schools typically require a training aircraft, say a Cessna 172, to fly a base leg around 65 knots, final around 60 knots to the threshold.

1.3 Vs is around 61 kts as Vs, power off, flaps down, is about 47 kts. Stall clean is around 55 kts from memory.

My question is as follows. Suppose you are on final, configured with full flaps for a landing, say just at 500ft. The engine coughs splutters and dies.

You are doing 65 knots. You judge you aren't going to make the field. Yes, I know I should be able to make the field, but that's moot just now. In addition at places like YMMB, some pretty flat approaches get taught in my opinion.

What is to stop you retracting flap to extend your glide?

I've never seen this discussed, let alone demonstrated or taught. The rule seems to be that once flaps are down they aren't going to be touched until you are on the ground. What am I missing here apart from the obvious issue of retracting flaps below the clean stall speed?

I've tried this at altitude in an approach configuration and their are no abrupt trim changes, etc.

The same issue relates to off field forced landings. Too much flap? Why not just retract some until your glide is what you want?

Handing over....

[SpyderPig]

My school teaches that if you are going to fall short, then get the flap back up. I learnt this first time I did a glide approach in the 172. Took flap as per normal in the 152, but fell short. My instructor explained that it "flies like a brick with full flap compared to the 152, so if you need to take some flap up to extend the glide on final, then do so."

This was also said by the ATO when I did the PPL test recently. High on base and final, side slip in. Afterwards we went over the forced landing leg lengths and heights. During this he also said "if you find yourself falling short, then clean the flap up to help extend the glide"

His reason was, you only have one shot in a real emergency to get it in the field, so do what ever it takes!

So some places are teaching it to students, like me :}

[TSIO540]

I understand that the main reason for not retracting flap as a 'rule' would most likely be because this type of training is being provided to students who cannot be relied upon to manage the decision; so after consideration of the way humans work under pressure there is a 'more reasonable' chance of success with the flaps as they are etc because there is 'less' to do and it will likely lead to a lower controlled touch down speed.

By retracting the flap (large changes in configuration) there is a considerable sink below the current glide path followed by an increase in speed... supposing you survive the extra sink and don't hit anything at your increased speed, you will be able to glide further from where you are when best glide AoA is re-established. :}

In doing this at low altitude e.g. <500 AGL you risk misjudging the extra sink as this procedure would only be done with an optimistic view of a worsening situation; and you also risk the higher possibility of entering a spin or a stall and dying for sure.

At higher altitudes or with small changes in flap (e.g. 40 degrees up to 30 degrees on a C172) and with more experience your chances of success with this procedure are much better...:ok:

[PA39]

Rule 1. NEVER extend full flap until you are assured of a landing ! Pretty basic training......that doesn't seem to be taught anymore. This was also said by the ATO when I did the PPL test recently. High on base and final, side slip in. .....Pretty sure side slips in a 172 are a no no.

[Ultralights]

in the broad strokes, flap creates a bit more lift and a lot of drag, there is a reason gliders are very slippery! to minimise drag.
the flap is just another flight control at your disposal, use it as necessary for safe flight, if your falling short in a glide, lose the drag and glide thurther.. of course, at best glide speed, for L/D ratio.

[SpyderPig]

Sorry, I should of clarified that I side sliped it to about 300 from about 600ft. No one has told me its a no no in the 172, though I try not to make a habbit of needing to!

I have only had to bring the flap back up once other than the time I was shown, and then it was only back from 30 to 20deg, so the attitude change was pretty small, and I felt more comfortable with my slope than before. I can full see how it would cause large sink going from full flap to none, I dont think I could ever see anyone doing that unless at great height.

I dont know if it makes any difference, but in the focred landing check list, we list flaps "as required" rather then "flaps full" which I heard once. I guess this lends itself more to being able to use them as need be before switching the master off?

[The Green Goblin]

First of all, you should not have 'full flap' in a C172 at 500 feet. I know they teach students these days to configure once they are established on final, however this will involve you 'dragging' it in all the way down final. This is 'poor' airmanship when considering the following aircraft, and a recipe for disaster if the situation you questioned happened for real. It may be okay at a GAAP (class D) aerodrome where everyone is doing the same thing, if you fly in the real world and do this with an RPT aeroplane up your behind, you could become an accident waiting to happen - especially if you were not making the required radio calls (which has happened to me on occasion).

Energy management is a crucial aspect of airmanship which is not taught. The trick is to fly the aeroplane all the way to the ground taking into account the current conditions without making large power changes, adding flap as required.

If you are following a slow aeroplane on downwind, don't fly wide, stay in gliding distance of the field, slow down and extend 10 degrees of flap. If you have the circuit to yourself, stay clean (not 3nm which seems normal for lighties these days) and extend flap as you require.

As a rule of thumb when I was flying piston VFR aeroplanes, I would not configure until 300 AGL (gliding distance of the threshold). Stabilized approach criteria is something you should be worrying about when you are flying an aeroplane where this is important.

In regards to your original question, you do as a Pilot what is required to fly your aeroplane safely in regards to the current situation. If this calls for raising flap to extend your glide to make the field - then do it. If this requires side slipping a C172 (which is prohibited in the POH with full flaps) then do it!

[Ultralights]

This is 'poor' airmanship when considering the following aircraft, and a recipe for disaster if the situation you questioned happened for real. It may be okay at a GAAP (class D) aerodrome where everyone is doing the same thing, if you fly in the real world and do this with an RPT aeroplane up your behind, you could become an accident waiting to happen - especially if you were not making the required radio calls (which has happened to me on occasion).

i think the poor airmanship side of it comes from a lack of situational awareness, i am capable of flying an approach at 30 kts with full flap, but if there is other traffic, then no way will i do it.

and whats the reason for NOT having full flap on a C152 at 500 ft?
full flap, plus a very steep approach into a tight field? then you can do a glide approach with full flap in any aircraft.

my greatest satisfaction is a when i can glide from base, yet still get full flap out and make a 30 kts landing right on my mark with 50 mtr landing roll and not touch the throttle.

[beat ups are fun]

I'm by no means an expert but PA39 summed up my point of view beautifully.

Rule 1. NEVER extend full flap until you are assured of a landing ! Pretty basic training......that doesn't seem to be taught anymore.

I was taught to have full flap out by about 400 feet, but it wasn't until my first Chief pilot pointed it out that i realized that this practice is "unsafe" in an engine failure situation. He suggested putting out full flap going over the fence, however I feel that's getting a bit late. I tend to throw out full flap when I'm assured I'll make it to the clearway, it leaves me enough time to stabilize the aircraft before the flare and if the donk did go U/S I'd be happy to put it in the undershoot if needed.

[The Green Goblin]

and whats the reason for NOT having full flap on a C152 at 500 ft?
full flap, plus a very steep approach into a tight field? then you can do a glide approach with full flap in any aircraft.

Because you have a couple of barn doors hanging out the back creating heaps of drag. This in turn requires you to use lots of power to maintain the profile. I've done my fair share of short field ALA operations and a standard approach profile IMO is the best way to get the job done.

Sometimes in the 172s/152s I'd leave 20 degrees out and land with that! Lets face it, they will land flapless in less than 400 meters!

[VH-XXX]

Again! Only apply full flap when you know you are going to make it to the runway!

You wouldn't want to apply it before that, there's no need and no recovery if your thrust is lost.

Sunfish, you should give it a go. Practice up a bit higher and see what happens to your glide when you drop the flaps and re-apply them.

[43Inches]

I was taught to have full flap out by about 400 feet, but it wasn't until my first Chief pilot pointed it out that i realized that this practice is "unsafe" in an engine failure situation.
Question why it is unsafe. I assume most here are talking about a powered approach and any aircraft which loses power with or without flap is not going to make the powered aiming point, it will fall short.

Unless you are all conducting a glide approach from the start from some point late base and final you will not make the runway even clean unless you are aiming originally to land a good way in or at excessively high speed.

The benefit of having flap already out is that no configuration change is necessary and the touchdown speed off field will be much less.

Some larger and high performance singles have very little hope of making the runway even from a close downwind position, especially if there is a headwind to the field. The best method to teach is always know how far you can safely glide in any configuration and have a clear area to put down off airport in the event of total power loss. If you can safely make the runway do it, if not take the off field option. Focusing too much on stretching a glide back to the field results in stall spin accidents and its better to land in the rough upright (better still a reserve, padock or oval) at low speed than arrive at the boundary fence inverted and lacking control.

I think the CP should not even take off as at some point after lift off the aircraft would not be able to safely glide back to the runway after an engine failure.

Any sideslipping should be done with caution in most trainers, especially with lower fuel loads as it can lead to fuel interuptions.

In any case discussion on the point should also involve some practice. In a real emergency best to stick to what you know and have done rather than try something new.

[The Green Goblin]

I think the CP should not even take off as at some point after lift off the aircraft would not be able to safely glide back to the runway after an engine failure.

A well known ex Kununurra CP used to demonstrate a turn back after take-off and expect his boys to be competent at the maneuver.

Whilst not always the best thing to do, it is another trick in the bag if it is ever required.

Some larger and high performance singles have very little hope of making the runway even from a close downwind position

What absolute bullocks :ugh:

High performance singles are usually very slippery and glide far more efficiently than your average trainer.

The only exception to this is perhaps the mighty C207 and a Cherokee 6. (and the C209). However if you can't make the field from your downwind position, you should rethink your circuits IMO. Something like a PC12, a turnback after takeoff is a QRH maneuver.

Unless you are all conducting a glide approach from the start from some point late base and final you will not make the runway even clean unless you are aiming originally to land a good way in or at excessively high speed.

Especially with the size of circuits that are promoted at the training fields these days. The circuits I flew, I would have been able to make the field in 90% of the circuit, and I kept this margin in every piston type I flew.

You can tell who the Grob/C152/C172 instructor is :zzz:

[Plow King]

This one has been touched on before

Retracting Flaps (http://www.pprune.org/dg-p-general-aviation-questions/278044-retracting-flaps.html)

There's a bit of drivvle there, but post #7 gets to the point - I think this bloke knew what he was talking about.

[Kwod]

Thank goodness for your wise words Green Goblin, I was really concerned with several of the posts.

Good to ask though - can't learn otherwise.

Energy management is exactly what it is in the smaller cessna's (et al)- each circuit can be different. Circuits should always be flown with possibility of engine failure in mind - too late when it has happened. Good practice for night circuits also.
Long time since I have flown the cessnas but I recall sideslipping with full flap prohibited in at least some single cessnas because
1. loss of elevator authority (due shielding)
2. gravitiy feed fuel system

:)

[PPRuNeUser0163]

BA38 anyone?

pretty sure that had a major impact (retracting the flaps) in the outcome of that flight at LHR..

[The Green Goblin]

Another thing Sunny, you're flying a C172!

KISS!!!

1.3 VS, bla bla bla, FFS IT'S A C172!!

What I suggest you do, put a post it note over that ASI and fly looking out of the big thing called a window out the front. Use your primary and secondary flight controls to take you where you need to go.

If you really want to learn something, go do a tail wheel endo in a Moth. It will really sharpen up your flying skills and get you looking out of the front of the thing rather than trying to treat it like a heavy.

To put it another way :p KISS!

GG

[The Green Goblin]

Here's another quick thought. You're disturbing a stabilised approach to reduce the risk in the event of an engine failure for the last 30 seconds of your flight.

No one is saying to disturb or conduct an unstabilised approach at all. They/we/I are just saying to not lower all your flap, until you are going to make it in.

Lets say its at night, and you've just flown YWGT-YMMB. So you've flown for the last 2 hours without being able to glide to a suitably lit runway and you're now worried about the last 30 seconds?

The last 2 hours you have been above LSALT in cruise with time to plan your glide and off field landing. A failure on final approach in landing configuration will have you in the weeds before you probably comprehended the gravity of what was happening. This is the time you need to be prepared for an emergency.

A little bit of prior planning and personal SOPs help prepare your recovery in a future upset.

[RadioSaigon]

You're disturbing a stabilised approach...

WHY oh why are you even discussing a "stabilised" approach??? It's an inappropriate notion when discussing the average GA airframe -up to & including most twins!!! You have neither the mass nor the inertia inherent in that mass to properly conduct a "stabilised" approach!!! Sure, there are elements of the stabilised approach paradigm that are utterly appropriate to GA airframes and pilot action, but the practice of attempting to "stabilise" the average GA approach is a complete nonsense!!!

Energy management is what GA drivers need to be concentrating on, along with appropriate circuit tracks and size. How many "pilots" do you see out there flying 747 circuits, dragging their airframe to the threshold with almost full power whilst sitting right on the back of the L/D curve in what is their interpretation of a "stabilised" approach?

Further, why not have full-flap in a C172 at 500'??? I used to have exactly that configuration most approaches in all sorts of conditions in some locations -in older 172's that had the 40 degree flaps too, not the more recently built 30 degree models. When you needed to get down, that was the way to do it. Admittedly, it's not always necessary, but when you need to use it, you need to know how -and don't try to overshoot from that configuration either. You'll wind-up as a smoking hole in the ground. Something like that will teach you about energy management in no time.

[ForkTailedDrKiller]

When you needed to get down, that was the way to do it. Admittedly, it's not always necessary, but when you need to use it, you need to know how -and don't try to overshoot from that configuration either.

RS, I was with you until that sentence!

What is the problem with overshooting with 40o flap? You just have to "fly" the aeroplane - yes, it does take a bit of muscle initially to keep the nose where it should be until you get some flap off - but it is easily done and should be routine for anyone flying those models of C172.

Dr :8

[swh]

What is to stop you retracting flap to extend your glide?

Nothing, as long as you adjust your speed (and trim) to correspond with the configuration. If you forget to trim, under the pump the aircraft will move away from the best L/D speed for that configuration, and you will have not achieved your aim.

I think most pilots would be better served by going straight for the carby heat if on short finals at YMMB if the engine splutters and dies, historically carby icing is the real issue, not how much flap one has selected or the size/shape of circuit flown.

Off field, what should have been taught is that first, if you are looking short, is to reduce the distance to touchdown by turning towards the aim point earlier, i.e. making crosswind, downwind, base shorter. Flap selection should be restricted to leave as much variation of control as possible over the angle and rate of descent.

I've never seen this discussed, let alone demonstrated or taught.

That would surprise me, when doing glide approaches in the circuit, or PFLs in the training area/NAVs, it is a standard consideration given in the briefing. I would find it hard to believe that at no stage this was covered. What you may have had is a recent light bulb moment and actually connected the dots and reinvented the wheel.

First of all, you should not have 'full flap' in a C172 at 500 feet.

Blanket statement like that are not useful.

The CASA standard that is expected to be taught is "turn onto final at about 500FT and select landing flap when rolled out on final", that is straight from their instructor manual. In reality if you turn onto final at 500 ft, and select full flap when rolled out, you will be just below 500 feet, but not by much.

It may be okay at a GAAP (class D) aerodrome where everyone is doing the same thing, if you fly in the real world and do this with an RPT aeroplane up your behind, you could become an accident waiting to happen - especially if you were not making the required radio calls (which has happened to me on occasion).

That would be poor airmanship on the part of the RPT aircraft. Too often I see pilots of light twins like the SF34 think they are the skygods at regional airports. Airmanship also applies to RPT aircraft, and they should fit into the local traffic pattern, not the other way around.

Airmanship and situational awareness is a two way street.

Energy management is a crucial aspect of airmanship which is not taught.

It is, every GFPT holder must be able to do a PFL, glide, and flapless approach.

A well known ex Kununurra CP used to demonstrate a turn back after take-off and expect his boys to be competent at the maneuver ( manoeuvre ).

Turn backs used to be taught around the world, the procedures comes from high performance (i.e. low drag) aircraft, they work in a glider, PC-9 or PC-12, but not in C152 unless you have enough energy to start with. The procedure is not suited to most GA light singles as pilots do not have the data at which height they will have enough energy to return. Once on crosswind, a 90 degree turn towards the runway become far more possible.

A turn back in a C172 would require a 45 degree AoB turn, which places the aircraft at the stall speed at low altitude in an emergency. The altitude loss for a 180 degree turn in "test pilot" conditions is 200-300 ft. A PPL holder being hit with an engine failure, and then a subsequent stall warning would not fair so well.

In a paper presented to the AIAA, 28 pilots with experience levels from 40 hrs to 5000 hrs were put in a simulator and told to expect and emergency at some stage.

They were given a takeoff clearance to climb straight ahead to 3000'. At 500 ft they were given an engine failure, 85% of pilots landed straight ahead, no crashes, of the 15% that attempted a turn back, 2/3 crashed from steep bank/stall.

Then they were repositioned for takeoff, pilots were told to expect engine failure at 500’, and they could handle it any way they wish. 90% of the pilots landed straight ahead, no crashes. Of the 10% that turned back, 50% crashed.

They were then repositioned again for takeoff. Pilots were told to attempt 180 turn upon engine failure, only 43% of them were successful. 85% of failures involved bank exceeding 55 degrees which is a low level stall/spin entry.

It is far safer to land in area that would require smaller angles of bank to maximise the stall buffer. This become even more pronounced in low visibility and at night, and with low experience.

Turn backs in GA aircraft at low altitude in my view are right up there with going past a perfectly good airport if you have a problem to save your boss a few bills, or not closing the second throttle on a light twin when not achieving some climb performance.

Something like a PC12, a turnback after takeoff is a QRH maneuver ( manoeuvre ).


You must have flown a different PC-12 than I have. The RFDS does teach turn back when above a certain altitude, they also teach an IMC cloud break procedure which gets you over the runway at 400ft/Vne if engine out in IMC, similar to what the RAAF do in the PC-9. They are not manufacturers procedures and I would not recommend either to anyone not having been taught them conducting them in anger.

WHY oh why are you even discussing a "stabilised" approach??? It's an inappropriate notion when discussing the average GA airframe -up to & including most twins!!!

Stabilised approaches need to be taught as people without much experience need a consistent picture to hang their hat on. They do not have the experience or judgement to fly a circuit as efficiently say a pilot that has done 1000 hrs of bungles joy flights.

The majority of people I have taught went on to fly other aircraft apart from GA singles. Even in a GA single, conducting an instrument approach requires the aircraft to be stabilised from the FAF/FAP. The earlier this concept is taught, the easier it is to move from the known (VFR) to the unknown (NVFR/IMC) training. Night training should also involve stable consistent approaches.

What is the problem with overshooting with 40o flap?

Nothing at all, as long as the correct procedure is applied.

[RadioSaigon]

I have to fess up, it's a while since I've flown one in any configuration... but from memory, with 40 degrees out in the breeze and even a moderate load (say 2 POB, 1/2 tanks) full throttle in that configuration resulted in a negative ROC. If a missed approach was necessary from that configuration, I started getting the flaps up (very carefully) from the instant the throttle was in.

American courts of the day (70's, 80's) took pretty much the same view, which very nearly sounded the death knell of the GA manufacturing industry around that time -and certainly resulted in Cessna reducing the available flap from 40 degrees to 30. The old crash reports were replete at the time with details of Yanks flying their 40 degree equipped 172's into oblivion on a missed approach from a 6,000' concrete runway!!! No editorialising necessary from me there...

So I guess really the problem with overshooting from that configuration (something I have done -apparently successfully :E) is, or should I say was apparently a lack of training and inept mishandling.

[Jabawocky]

My question is as follows. Suppose you are on final, configured with full flaps for a landing, say just at 500ft. The engine coughs splutters and dies.

You are doing 65 knots. You judge you aren't going to make the field. Yes, I know I should be able to make the field, but that's moot just now. In addition at places like YMMB, some pretty flat approaches get taught in my opinion.

What is to stop you retracting flap to extend your glide?

Well there has been lots of thread drift here.............but the best answer to you question is............ Ask Capt. Peter Burkhill.

Simple question and a pretty simple lesson being tought here.

_atWJ-tQezk

[Jabawocky]

Here is another worthy video to watch.

This is NOT a suits all demonstration, but it does make you think carefully about how you would deal with a turnback scenario and how best to train for and execute.

If you know you can....its better than a controlled crash.

If you only think you can..........you can't.

Best to know what you can and can't do.

Aerobatics in California (http://www.aerobats.com/turn-arounds.html)

J:ok:

[slamer.]

Accident description

Status
Date:27 DEC 1986Time:13:48
Type:de Havilland DH-114 Riley Heron 2B (http://www.pprune.org/database/type/type.php?type=191)
Operator:Sunflower Airlines (http://www.pprune.org/database/operator/airline.php?var=5236)
Registration Q-FEFC/n / msn:14056First flight:1955
Crew:Fatalities: 2 / Occupants: 2Passengers:Fatalities: 9 / Occupants: 12Total:Fatalities: 11 / Occupants: 14
Airplane damage:Written offAirplane
Location:near Nadi (Fiji (http://www.pprune.org/database/country/country.php?id=DQ))
Phase:Approach (APR)
Nature domestic Scheduled Passenger Departure Savusavu- Nadi, Fiji

At 500 feet the right flap jammed at 35° while the left one continued to 60°. The aircraft rolled to 90° bank, struck the ground and cart wheeled short of runway 21.
PROBABLE CAUSE: Unsecured non-standard flap attachment pin migrated upward and lodged in a lightening hole.

[SpyderPig]

As Im at work, I cant watch the above vids but I can say that I have been shown the turn back once and it was followed by pretty strict instructions on its use.

In a 152 we set out to perform this maneuver, where just short of 700ft(xwind turn for us) the instructor pulled the power and performed the move. Back on the strip he asked me to perform this as per his prompts, which I did and we landed again safely (quite day at the field).
His instructions were that it was possible, BUT only if you can check these 3 things off can you attempt it.

Good head wind on takeoff, giving a good tailwind to help get back.
Never below 500ft, and even then it shouldnt be below at least 600ft.
No one following you on the runway.

Before anyone says anything, he drove home that landing ahead option 1 and 1a. The only time you should consider this was if in your pre take-off brief you know there is no a safe field off the end of the runway to land in.
Never exceed 30deg AoB.

Ive never attempted it again or been asked to perform it.
Just giving a newbie’s point of view on whats being taught :ok:

[Jabawocky]

Never exceed 30deg AoB.

SpyderPig
I think when you get to see the video's you will change your mind on that. Seems that more is good. I am going to do some tests myself some time soon to see what results can be achieved safely.

[RadioSaigon]

Stabilised approaches need to be taught...

That's where we're going to have to agree to disagree I reckon. I'm of the opinion that trainees need to be taught appropriately to fly what they are flying now, not what they may or may not fly several years and thousands of hours down some future track -when they can be properly and appropriately trained in what they need to know, in what they need to know it in. The "consistent picture they need to hang their hat on" when training and in the early stages of their career does not come from attempting to fly an inappropriate "stabilised" approach. They need to be getting trained to see and accurately perceive the sight-picture in front of them and manage their approach path and appropriately respond to managing their profile to achieve the desired result. Instructors that train their student on the basis of "You'll never fly a [insert desired heavy-metal here] if you do that" are the bane of the industry IMO, not serving themselves, their institution or their students well.

Jabawocky's 1st video is one of the examples I was going to quote myself... their stabilised approach went all to hell in a hand-basket when the power faded. Had a stabilised approach been the only trick in their arsenal, how do you think that would have wound up? They were able to see and do what was necessary to achieve a bloody good result because they were trained to see and respond to what was necessary rather than slavishly follow a formalised procedure. Likewise, Captain Sullenburger of Hudson River fame -how "stabilised" do you reckon his approach was?

The Politically Correct stance of "train 'em for the majors" is bull**** IMO. Many will never make it, some don't want to. They still have years of active GA flying in front of them and need to be trained to fly what they are in.

[Captain Sand Dune]

Firstly in reply to Sunfish I would say that retracting flap would be OK if overshooting as long as the IAS is adjusted appropriately and the aircraft trimmed, as previously stated. Certainly worth a try if all else has failed, anyway! For information, the ADF teaches CT4 students to initially pick an aiming point 1/3 into the selected landing field, then when on final full flap is selected to bring the aim point back in order to take full advantage of the landing distance available.
Secondly – my 2c on glide slope management for powered approaches. The ADF teaches CT4 students to roll out final at 500FT AGL then select full flap. The resulting glide slope is significantly steeper than those flown by other GA types I have observed that also are using full flap. I estimate that the full flap glide slope some GA drivers are using are shallower than the glide slope we teach CT4 students for flapless approaches. As others have stated, a case of trying to fly 747 circuits in lighties in my opinion. Why?
Thirdly – turn backs. Reciprocal turnbacks are possible in the PC9. However these manoeuvres are not to be briefed, demonstrated or taught to students. And with good reason. Remember the PC9 has an ejection seat that works quite well. Why risk stalling the aircraft at high AoB trying to make it back when the Martin Baker roadside assist plan is available?
As a first tourist QFI on the PC9 I recall practicing reciprocal turnbacks with other QFIs. The “manly” thing to do was to hack the throttle at 500FT AGL and try to get it back on the runway from there. Frequently this required pulling to the light buffet in order to haul the nose around. The lunacy of this eventually dawned on me after practicing these manoeuvres at night, scaring the sh!t out of myself.
A couple of thousand more hours on the beast later, I wouldn’t consider a reciprocal turnback in the PC9 below 1,000FT AGL. Remember the ADF has spent a motza installing ejection seats. They’re not there for looks.
Reciprocal turnbacks are only practiced (sans students!) in the CT4 to demonstrate the absolute futility of attempting such a manoeuvre in that aircraft.

[VH-XXX]

I've practiced and pulled off the odd turn back successfully, no dramas, but that was ideal conditions. As we should all know it wouldn't take much for things to go pear-shaped; one thing leads to another when the proverbial hits the fan.

[Jabawocky]

My question is as follows. Suppose you are on final, configured with full flaps for a landing, say just at 500ft. The engine coughs splutters and dies.

You are doing 65 knots. You judge you aren't going to make the field. Yes, I know I should be able to make the field, but that's moot just now. In addition at places like YMMB, some pretty flat approaches get taught in my opinion.

What is to stop you retracting flap to extend your glide?

What is there to stop you? nothing. Reduce drag ....say F20 or there abouts. Course pitch if you can and have a windmilling prop.

[SpyderPig]

Jaba, your correct saying my tune would change after watching the aero vid. From memory Im sure he said I should try to nail 30deg and best glide speed during the turn, but we were also at around 650-700ft, and again he said it would depend on good conditions, like XXX described.
Anyway, when I go for a nav this week Ill still be prepping for the fields off the end of the strip:ok:

My circuits are a 300ft decent on base and a 700ft final with flap 30 at around 500ft. 1/3 strut spacing downwind, 45deg to threshold base turn. It seems like a pretty standard pattern to me, I hardly think this is airline stuff? We have RPT at our CTAF, and when ever the PAPI is on we pretty much ignore it as our profile is more like 4 or 5 degree profile due to being much smaller and having a steeper profile. Its all good to train students to act in a professional way "gettin em ready for the majors" but part of that should be teaching people to fly their current type correctly?

Back to the flaps though, a small change of one stage just extend the glide a little shouldnt be a problem I think. But if you find yourself wanting to pull back more than that, chances are you've made a meal of it and probably shouldnt be up there flying in the first place. They drummed it into me pretty hard about getting it right, you only getting one shot in a real failure.

[swh]

I'm of the opinion that trainees need to be taught appropriately to fly what they are flying now, not what they may or may not fly several years and thousands of hours down some future track -when they can be properly and appropriately trained in what they need to know, in what they need to know it in.

The majority of pilots issued with a new CPL in Australia transition to a multi-crew aircraft with less than 250 hrs total time, and normally do so within 6-12 months of being issued with the CPL (some are asked to sit and wait for a bit longer like during the last downturn). A lot of those CPL holders are trained for overseas airlines (be around 30-40%).

The "consistent picture they need to hang their hat on" when training and in the early stages of their career does not come from attempting to fly an inappropriate "stabilised" approach. They need to be getting trained to see and accurately perceive the sight-picture in front of them and manage their approach path and appropriately respond to managing their profile to achieve the desired result.

A stabilised approach means being on the final approach course from where a landing can be carried out in the landing configuration without exceeded acceptable speed, pitch, and roll variations.

It does not mean a 3 degree ILS approach from 3000'/10nm.

Had a stabilised approach been the only trick in their arsenal, how do you think that would have wound up?

Do you mean if they had not changed configuration ? They still would have landed within the airport perimeter on the runway centreline. The lights and antennae in the clearway are frangible by design. Even after changing configuration, they resumed a stabilised approach.

Likewise, Captain Sullenburger of Hudson River fame -how "stabilised" do you reckon his approach was?

That was also stable, for a ditching. Gear up, on speed, wings level, and pitch attitude within the stabilised approach criteria. If they were unstabilised, they would have ended up like the Ethiopian 767.

It is important to recognise that its not just airlines that use stabilised approaches.

I think most people do, they just do not recognise what they are doing is actually a stabilised approach. Airlines give the crews direction as to what parameters trigger an unstabilised approach, I have only similar words in the upper levels of GA where high performance aircraft are operated.

If you fly most bugsmashers the way the book says I'm sure you'll find yourself very close to the glide profile anyway. Personally I would argue that this is stabilised; I haven't seen a broad definition that states a requirement to be on a 3degree profile in order for it to be called stabilised.

Flight manuals and pilot operating handbooks of light aircraft are not that specific in a lot of cases as to what the standard landing configuration is, it may just say flap "as required" or "as appropriate", if you have fixed undercarriage that landing configuration deviation is also removed from the equation. It would them come back to what performance figures are available, if a pilot decides to land in a configuration for which they do not have performance figures, it may void their insurance.

In larger aircraft, manufacturers get more specific with their published procedures, and hence their operations are less variable.

I hardly think this is airline stuff?

If you are doing it without large variations in configuration, speed, and attitude, and complete your landing checklist, it is airline stuff. That is a what airlines call a stabilised approach. Flying a circuit in a airliner is still much the same as a C-172, the speeds and heights are a little higher, but the principle is the same.

[triadic]

What I was taught way back was:
1) Don't select full flap until a landing (on the runway) is assured,
2) Don't select flap, when the result will be the requirement to add power to overcome the associated drag.

I suggest that if the above is followed, then the circumstances outlined in the question at the start of this thread is minimised.

These days I believe there is far too much emphasis on following strict procedures and not in teaching students that there are other options on the menu that may be suitable. The student must be able to think outside the box!

[training wheels]

As for the 'keeping the circuit tight so that you can glide to the runway if you have an engine failure' , that would mean a glide approach for every circuit you do, would it not? Either that, or you land long with a normal power approach.

[anothertwit]

The majority of pilots issued with a new CPL in Australia transition to a multi-crew aircraft with less than 250 hrs total time, and normally do so within 6-12 months of being issued with the CPL (some are asked to sit and wait for a bit longer like during the last downturn). A lot of those CPL holders are trained for overseas airlines (be around 30-40%)

who's a jolly joker!!! where did you get this info from? or are you just trying to drum up some business for your school?

did you know that 75% of all statistics are made up.............:hmm:

[ZappBrannigan]

SWH, what you're describing pretty much mirrors what I've been taught since I started flying charter. That is, every approach is required to be stabilised (yes, even in a 210) - the only thing that changes with type/weight/size of aircraft is how far out this must occur. And that "stabilised" doesn't have to mean a perfect 3 deg slope - it just means being able to continue the approach to the runway without any gross changes in configuration or attitude, and with airspeed continually reducing to reach threshold speed on short final.

What I was taught way back was:
1) Don't select full flap until a landing (on the runway) is assured,
2) Don't select flap, when the result will be the requirement to add power to overcome the associated drag.Again, number 2 here describes how I was taught - approach stabilised from X miles out, with gear and flap extension on schedule to bring you to your landing configuration and airspeed, without any changes to throttle setting from 1st flap extension onward (of course, throttle adjusted as required on final, but in a perfect approach, shouldn't be required until the flare).

I experienced what I see as the "opposite" view a few months ago - riding in the back of a 210 with a pilot I'd never met - he kept around 20" on with an aiming point a few hundred metres past the threshold, then on very short final, cut the power to near-idle, dumped full flap and shifted his aim point to the threshold, resulting in a very steep approach for the last half-mile or so. Nothing really out of whack, airspeed pretty much where it should be and a good landing not too far past the threshold - but it hit me as a completely opposing theory on how to fly a piston single approach. Not what I'd call stabilised. If he'd had an engine failure on short final though, he may well have been in a better position than I'd got used to flying a C206/210. But I wouldn't like to jump out of the 210 into a PA31 and use the same technique.

I'm not saying this is "wrong" though - some here will probably say this is how they do it and any other way is crazy. Don't know.

The concept of always flying a stabilised approach has always been completely logical to me though, and make the transition to heavy piston twins (and I assume turbines and beyond, not there yet) a lot more straightforward and logical.

[The Green Goblin]

Look guys, it would appear you all do not know the definition of a stabilised approach.

I'll post it here for you:


1. The aeroplane is on the correct flight path
2. Only small changes in heading and pitch are required to maintain the correct flight path
3. The aeroplane is not more than Vref +20 and not less than Vref
4. The aeroplane is in the correct landing configuration
5. Sink rate is not greater than 1000 feet
6. Power setting is appropriate for the aeroplane configuration
7. All briefings and checklists have been completed
8. Stabilised by 500ft in VMC or 1000ft in IMC


This is in regards to an above 5700kg aeroplane. Whenever we are talking stabilised approach criteria, this is what is being referred to.

In regards to a light piston single or twin, there is no reason why you can't use this as a reference, however you should fly the aeroplane as is required to do so in the interests of safety.

In regards to the ongoing debate about the 3 degree glideslope, the requirement is to be on the correct flight path for the approach that is being flown. Some require more, others less. A piston single feels mighty awkward when you are trying to fly a PAPI!

[Kharon]

Go back to flying school. Who was it Wilbur or Charlie ??.

Certainly not the mad fool Orville. FFS.

[slamer.]

Forget the theory, reconfiguring flaps close to the ground should be done with great care regardless of type .... and only when absolutely necessary.

[VH-XXX]

The last pilot that I saw "reconfiguring" their flaps close to the ground, destroyed their aircraft. It was repaired, but it wasn't cheap. Everything in front of the firewall tore off. They released the flaps in a go-around and belly-flopped into the ground. They exited the aircraft by stepping out where the windscreen was :rolleyes:

[Jabawocky]

Turnback successful from 400 feet, and had to use full flap! We may have made it from less :uhoh: These tests were done at 45 degrees AOB.

As soon as Chuckles edits the video I am sure he will upload it.

Disclaimer: not all aircraft will be capable of doing this.

[T28D]

A turn back from 400 ft in any aircraft is irresponsible and I hope there are no young people learning who read this that ever attempt such a patently risky foolhardy manouver.

400 ft and silence , land straight ahead and give the aircraft to the insurance company.

NEVER turn back at low level.

[Chimbu chuckles]

Rather absolutist there T28D - do you include Gliders in the statement 'in any aircraft is irresponsible'?

You'd be aware that glider pilots are required to demonstrate a turn back from <300' (if memory serves) in the event of a broken tow rope before they are allowed to solo?

That being the case it would seem to me that its merely a matter of how good a glider you're flying. The RV10 is an exceptional glider. Mr Vans designed one hell of a wing.

Jaba was curious and so was I. I strongly suspected the RV10 would do it with ease and that was how it panned out. After some practice at a safe altitude to blow off the cobwebs (its been decades since I was taught how on an Instructors Rating course - and not long after did one in anger in a C182) we did a couple on takeoff from 06 at YCAB.

Negligible wind. The first time we 'failed' the engine at 500' and we were so high lining up on 24 it would have required aggressive sideslipping with full flap to not over run the end of the runway.

The second time we 'failed' the engine at 400' and still managed to comfortably get around and land on 24. With a little headwind and 15 degrees of flap I reckon 300' would be quite doable. From 600-700' we could have turned left or right and after a short downwind leg turned a further 180 degrees and landed on 12/30.

We allowed a couple of seconds 'reaction time' on each occasion although I fall into the 'surprised when the engine doesn't fail' category and in any of the real engine failures I have had I certainly didn't sit there dumb founded for several seconds.

When I have had time to edit/format the vid I will post it.

[Sunfish]

XXX:

The last pilot that I saw "reconfiguring" their flaps close to the ground, destroyed their aircraft. It was repaired, but it wasn't cheap. Everything in front of the firewall tore off. They released the flaps in a go-around and belly-flopped into the ground. They exited the aircraft by stepping out where the windscreen was


I agree, not a good idea. However what I'm talking about was retracting flap on approach at 1.3 Vs. That should provide a slight pitch up and a better glide angle.

Whitts flying has this to say:

Flap Emergency (Instructor)
A simulated emergency-landing situation that deserves instructional attention is that of engine-failure on short final. Create the following situation on a 5000' or more runway. Arrive at short final with full flaps, at least 1500 RPM and the slowest approved approach speed. At 400' take off the power. The student should immediately remove all flaps and use the yoke to maintain the same approach speed. The initial reduction of power should make it obvious that the aircraft will be unable to reach the runway in its full flap configuration. The immediate removal of flaps will cause a sink of nearly 200'. These negatives are soon seen to be offset by the flatter glide and extended glide path made possible by the absence of the flaps. When done smoothly, touchdown should occur about 2000' down the runway. Introduce this procedure shortly before solo. In 35 years this knowledge has prevented at least two off-airport landings by my soloing students at Concord CA..


http://www.whittsflying.com/web/page3.14Use_of_Flaps.htm


I would add that no one has ever taught or shown me that, and I ain't tryin it on my own.

[b_sta]

Ah, yeah, I think I'll leave that one for someone more foolhardy than myself to try! :ooh:

[VH-XXX]

I "may" know of someone who practices their EFATO and Glide Approaches by switching the engine off. Seems to work well for them. The added pressure of not having an idling engine appears to be directly proportional to making it onto the ground safely!

It's all good practicing it until you have 30 knots headwind - things change rapidly then!

[T28D]

Chimbu, yes Glider turn backs on cable release or break is 300 ft so is the base turn in a normal circuit. Also cct is flown very close in and the glide ration of the average training glider is twice that of a conventional powered aircraft.

Absolutist maybe, I was referring to powered aircraft and people turning into instant test pilots initiating low level turn backs.

The fact that you "got away with it" is testament to the existence of an element of lucky bravado, to celebrate that is in my view irresponsible.

[Aerozepplin]

I don't think Chimbu's post displayed any elements of "lucky bravado".

The blanket “don’t turn back” is a good one to teach in my view, because it is very dangerous, and if you haven’t trained for it you’ll be putting yourself in a very poor situation. However, in the situation Chimbu described a logical series of steps were followed beginning with high altitude trials and progressing to a realistic situation.

This seems to me to give them the knowledge of under what weather conditions, at what height, and in what manner a turn back can be accomplished in their aircraft.

[43Inches]

If your aircraft has very good glide performance a turnback may be possible. As has been said gliders, PC-12 and some light aircraft with either good rate of climb after take-off or very high aspect wings will have a chance.

The problem has been those that have thought it possible in a Lance, Bonanza or similar that have stalled and crashed as a result. Some have been over open cattle country at the time which was little worse than a poorly maintained grass strip. The ATSB has many unfortunate acounts of attempted turnbacks which have resulted in loss of life. There are also many occurances of off airport landings which have been sucessful (light injuries with no loss of life).

Two major issues with a turnback are;

1. The much greater risk of loss of control.
2. Increased groundspeed at impact if any headwind was used on take-off.

In the case of the 30 kt headwind your ground speed at impact would be 60 kts greater turning back, that's assuming you were under control and used full flap and minimum touchdown speed. In a trainer your groundspeed at touchdown landing ahead in these circumstances would be less than 20 knots, even if you hit things it would be survivable.


The blanket “don’t turn back” is a good one to teach in my view, because it is very dangerous, and if you haven’t trained for it you’ll be putting yourself in a very poor situation. However, in the situation Chimbu described a logical series of steps were followed beginning with high altitude trials and progressing to a realistic situation.

This seems to me to give them the knowledge of under what weather conditions, at what height, and in what manner a turn back can be accomplished in their aircraft.


Agreed

Its also good to remember that even in your aircraft a lot of things can change, especially if damage causing additional drag or airfoil deformation occured with the failure. Attempting a high wing loading maneuvre at low speed with damage to the airframe could result in anything.

[T28D]

Just a little check on the mathematics, if you were to take of into wind ( normal practice) and say the wind was an average 15 knots at ground and given some shear say 18 knots at 500 ft.

So a take off at 60 knots will give a ground speed of 45 knots and then there is an acceleration to climb performance as the aircraft accelerates, then silence at 500 ft, now you have to contend with a turnback to a downwind of initial say 18 knots and if you make it on final of 15 knots into a very shortened available bit of runway at a ground speed of 75 knots assuming the approach was stable at 60 knots.

You are most assuredly in test pilot country, if you make it onto the runway , then you have to stop using a well out of spec braking system and potentially difficult runway surface.

On a 1000 metre bitumen runway this would be hazardous in the extreme, onto an 800 metre gravel ungraded strip tantamount to suicide.

This is all without considering Density altitude which could cramp your style much further and considerations of whether or not you are close to AUW.

[Van Gough]

Too often I see pilots of light twins like the SF34 think they are the skygods at regional airports

I'd hardly describe a Saab 340 as a "light twin":confused:

[Chimbu chuckles]

Lotta **** being posted on this thread - about par for the course for Pprune whenever a technique/technical question has been asked.

For starters any instructor that insists light piston engined aircraft should be flown on 'stabilised approaches' in the same vein as a heavy jet (fully configured at 500') needs belting around the ear 'ole.

A 'stabilised approach' in a Cessna/Piper/Beechcraft is one where the aircraft is slowly decelerating all the way around base/final, with configuration changes taking place at the ideal altitude/speed so that you arrive at 50' at 1.3vs minimum. Maybe a little faster for all the usual reasons.

Final flap selection should take place around 200-300'. If you don't need full flap land at partial flap - if for no other reason than curiosity

Power setting should be a lot less than is seen in 98% of flying school circuits.

Final approach path a steeper than a Papi/Vasis/ILS.

If you're teaching fully configured/1.3vs at 500' STOP INSTRUCTING.

If your instructor is insisting on anything like the above change instructor - if the new one is the same take your $ somewhere else.

The mere fact that above is recommended in a CASA document should be warning enough - most remaining CASA employees are unemployable career failures - the good ones give up and leave. They are the LAST people we should look to for guidance on how to fly light aircraft.

At ANY point on base/final you should be able to make the runway after an engine failure by no other expedient than merely NOT configuring ANYMORE.

That is what is meant by 'not taking the last stage of flap until you KNOW you can make the runway'. Mid base/750'/flaps 10 you should be able to make the runway if the engine fails. Base turning final/flap 20/500' you should be able to make the runway if the engine fails. Mid final/flap 30 you should be able to make the runway if the engine fails.

If a student is truly incapable of selecting a stage of flap, making a slight pitch adjustment and trimming at any altitude above 200' seriously suggest he take up kite flying.

I am serious. You instructors are there to teach people to FLY not manage (in the airline sense of 'manage') especially pre CPL training.

As to turn backs - well don't ya just love the twits who start spouting numbers that suggest its impossible.

"Well if you were taking off into a 30kt hwc...":ugh:

Ok hands up who has EVER taken off into a 30kt HWC let alone lately. I have 15000hrs and apart from the odd BIG day during the SE Tradewinds at Port Moresby I don't think I have ever. How did you manage to taxi your C172 to the runway without taking out a hangar/tied down aircraft?

If you did takeoff off into the teeth of this gale you would be still over the runway at 500' and, yes, if you turned back you would likely crash somewhere back along the final approach path for the runway...and I would laugh at you, ridicule you and call you a moron to your face.

If you killed yourself I would feel great satisfaction that you have removed yourself from the gene pool while feeling genuinely sad for any people you took with you.

If you try and turn back in an aeroplane you don't ABSOLUTELY know will do it - or without training and lots of practice - or in conditions where straight aheadish is a better bet - on the spur of the moment - or an engine failure after takeoff is a total surprise - or despite the fact you're incapable of consistently doing a gliding 45 degree bank angle turn at +/- 2-3 kts of the correct speed, just on the first nibble of buffet, at low altitude, BALANCED then see my gene pool comment above.

Seriously.

MOST pilots SHOULDN'T attempt a Turn Back in MOST aircraft MOST of the time.

But SOME aircraft can do it and a properly trained pilot with the requisite skills in one of THOSE aircraft should, I believe, have it in his bag of tricks. Jaba has only sat and watched (he did fly a few at altitude)...one day he might be in a position to add it to HIS bag of tricks. One day he MIGHT find himself in a situation where its an appropriate choice.

Knowing what I know about the Rv10 and with my general experience gliding this aircraft (not just yesterday) if I was departing YRED 07 and had an engine failure would I turn back or put the aircraft into Deception Bay?

You tell me. Note the first approach is a 'normal' glide approach from downwind at 1000'. On each glide approach, including the turn backs, the only things I am changing after engine 'failure' is prop pitch and flaps.

uvTUW28JnpY

Sorry for the poor quality - youtube reduces the quality and it was late in the day with low light.

[VH-XXX]

That video would have been much more exciting if it had been made at Moorabbin, Bankstown or Archerfield on a Saturday morning :D

[nitpicker330]

Looks like Caboolture to me?

It might be a bit more fun at YMMB on a busy day!

[converge200]

The RFDS only teach turnbacks from 1000' agl. Below that your landing ahead. Personally if I can, I depart away from my destination so I set course overhead. Then if the engine fails on departure I have a chance of making it back.

[T28D]

So this doesn't degrade into a Pissing Contest, I make this observation in support of my "Absolutist" position.

Can a turn back from 500 ft be successful, yes it can under very controlled circumstances by very experienced pilots who are current on type.

Should turn backs from 500 ft be done, a whole different argument and to that I say the answer is NO.

[BBMouse]

All you experts can keep your advice,

I think ill look at the number of engine failures on final vs number of incidents due config changes/ runway overruns

and then make my own mind up on whats important.

Mouse