Flaps 10 glide during engine failure
 

When you have an engine failure on single engine aircraft, do you use flaps 10 (for C172, so generally, do you select lift flaps) as soon as possible, or do you initially glide with flaps up?

What are the pros & cons of using lift flaps early during an engine failure?

The POH for the C 172 is quite specific on this question. It says that best glide speed (between 65 and 68 kts depending on the model) should be established as quickly as possible and the "Maximum Glide" chart specifies Flaps Up.

The right answer is to fly as the flight manual states. I expect that it specifies a flaps up glide. When your glide transitions from a glide for distance to the approach for landing, obviously some, hopefully all flaps will be extended.

Early extension of flaps will increase lift, which you do not need ("cause you got no thrust"), and will increase drag, which you really don't want then. Consider that increased drag will increase your descent angle. That might be what you want, but be careful what you ask for, you might get it. Remember that chances of survival are inversely proportional to angle of arrival. When you develop that steep descent angle, you'll want to convert it into a very shallow one before landing. This requires energy, which you do not have from the engine, so its you inertia only. With a lot of drag that goes away fast.

When I do familiarizing flying with owners in their STOL modified aircraft I would demonstrate, and train not to glide at speeds slower, or with more drag, than the flight manual states. You can do it, but slower means less inertia, and when you go to flare, there;s nothing left, and you stall and drop in unable to arrest your rate of descent.

You'll find many cases where flight can be accomplished at slower speeds or different configurations than the flight manual states. The plane might do it, but you may have unwittingly given up a reserve of safety (inertia) which did not even think about.

Yes, safely learn and understand, but ultimately you'll find the flight manual way is the best way - I've done a lot of flight testing, and that's what I have found....

Clean or Flaps
 

Extending Flap does a number of things. The camber of the wing is increased and thus more lift is produced for a given airspeed. Adversely, more drag is produced also. The aeroplane will have a better Lift/Drag ratio with the flaps retracted and when flown at the best glide speed will maximise the glide distance. Flying faster or slower than Best L/D Speed will reduce the glide distance. Flaps are best left up until a landing is assured.

Paint yourself into a corner
 

Selecting flap before landing is assured is throwing away performance, as said above the best lift/drag option is flap up at the PoH speed for the aircraft you are flying.

You can always get rid of energy with more drag but you can never get it back !

This whole 'don't select until landing assured' discussion gets to me. Let me explain using the ubiquitous 172/152/PA28 with two examples.

Firstly a powered approach (I'll not get into the merits of such an approach, let's just take it as read that people fly these). If an aircraft is set up on a powered approach and at a sensible approach speed the landing is never assured. Dropping flap at 300ft or whatever is only going to forshortened the landing point. Agreed, you could drop the last stage 'over the fence' to drag off a few knots but do we really wish to reconfigure at this point?

Similar scenario but a glide approach. In this scenario the flaps are acting as your engine - controlling angle of descent. If your landing is 'assured' with two stages and you then drop the last stage (drag?) your landing s still assured but not at the same location. Again you will drag the landing point closer to you. This is why most sensible instructors teach that a glide should be aimed towards the far end of the landing area and pilots should adjust this point with the application of flap.

So, in summary, the 'landing assured' phrase needs to be understood in its entirety. Drop flap and do nothing else with the aircraft and you have moved your landing point. Your landing is only assured if you understand this and plan your approach accordingly.

I do not use flap until I'm certain that I will make it into the field and want to move my aim point closer. Lowering flap will spoil your lift to drag ratio, which I certaintly would not want to be doing until I am certain I will make it into the field.. Same as when I'm flying a glider ill fly a profile and only bring the spoilers out to move the aim point closer. I certainty would rather be slightly above profile than below.

Keep the flaps up until over your chosen field. If you have tons of extra height, expend it in mini circuits while inspecting the field and approaches.

If there is any wind, downwind at slightly less than best glide speed gives you more choices and the option of doing a 180 into whatever looks acceptable.

Remember that a good approach to a poor field is much better than a poor approach to a good field.

Question: do you know how much altitude you will lose in a power off 360?

Once over the field, minimum sink speed is more appropriate than best glide as it gives you more think time. But as a glider pilot, I sometimes spend over half an hour "inspecting" a field before it turns out either that I have to land there or I find a thermal that gets me away.

For base and final, go back to at least approach speed and use flaps.

A good exercise is power off approach from the circuit. Bring the instructor along the first few times as he will remind you to have enough speed to flare with full flaps.

"Landing assured"? Oh its definitely assured if the engine's stopped:}

Excellent advice. When the engine stops the insurance company just became the proud owner of the aircraft. What the airplane looks like when it comes to a stop is immaterial, the only consideration is the health of the people in it.

The best way to ensure a successful outcome is to make sure the aircraft contacts a more or less level surface in a level attitude. Too fast is always better than too slow on the approach as you can always smash the aircraft into the ground if you have to. Too slow usually means coming up short and hitting something in the air and at flying speed :=.

Finally remember 80% of engine failures are caused by the actions or inactions of the pilot, so the best way to deal with an engine failure is to not let it fail in the first place.

I know I've banged on about this before but all powered pilots should go solo on a glider first. It would take all the fear out of a forced landing, every landing in a glider is power off, you get one go and that's it. You don't read about glider pilots ballsing up a field landing.

Edit: I know the speeds and glide angles are different etc etc but the principle is the same.

I have to say I disagree. I have taught 3 PPL's who started training with a glider license, albeit none with a lot of glider time. The basic stick and rudder skills certainly benefited from the glider time but I was surprised that all 3 took a bit of time picking up the PFL exercise. They all commented that they had so much more time to set up the approach in the glider and the fact that the spoilers could be treated like a pseudo "throttle" made the whole thing much easier in the glider. They are also programmed to always try to find a landing spot that will not damage the aircraft, a potentially lethal reflex in a powered aircraft that has suffered an engine failure.

In any case you are much more likely to experience a partial engine failure which will more than likely still allow you to maintain altitude, than a complete failure. I think flight training does pilots a huge dis service by emphasizing what is in the real world the statistically most unlikely possible scenario, a sudden and total loss of power with no warning.

Can't argue with your views BPF, you're vastly more experienced than me but I can only speak for myself when I say that I never had any trouble with PFL's and I can't say that the thought of a donk failure bothers me too much. Of course I'd rather not have one but I would hope I would be fairly comfortable if I did have one.

I always fly like I'm expecting one at any rate, so I always keep a weather eye out for a landing spot and never fly over big swathes of city type area.

I have to agree with BPF. Field selection and circuit management is a whole bunch easier coming down at 120 fpm than at 800 fpm.

And, glider pilots can and do have outlanding accidents, sometimes fatal.

You can get your glider license without ever having done an outlanding -- or talking to ATC;) . In fact the Bronze badge, which most clubs require before turning you loose for your 50 km cross-country is a post license exercise.

So it does not surprise me that BPF's licensed glider pilots required more teaching for PFLs. A PFL requires a lot to be done in a short time while outlandings are usually leisurely affairs.

That's a bit of a sweeping statement. The requirements for glider licenses are somehow not standardized by ICAO (or nobody follows the ICAO recommendation, I don't know).

In the UK, AFAIK, the BGA *exclusively* uses the FAI badge system. They never issue you with a formal license.

In the Netherlands, there is a Glider Pilots License (which I have) which indeed can be done within 5 km of the field, and without any radio usage whatsoever. Only once you have the GPL will you start your x-country training.

EASA is going to change all this though (somewhere in 2014 I believe). There is going to be a formal EU-wide accepted Glider Pilots License, and this license will include x-country experience. From memory, the experience requirement is a 50 km solo flight or a 100 km dual flight.

Canada, US, Australia may all be different. I have no idea.

Canada - 15 hours ground school, 60% on TC glider exam, 6 hours glider training under supervision of a Glider Instructor, including a minimum of 1 hour dual and 2 hours solo (including 20 take-offs and landings) and pass a skills test.

No requirement for cross-country or off-field landings.

Of course, all ab-initios take much longer than the minimum hours.

The same European legislation that created the EASA PPL and LAPL(A) also created the LAPL(Sailplane) and Sailplane Pilots Licence (SPL). These licences all became available on the same date in 2012. However, there is a derogation in force which allows until 7th April 2015 for the UK to complete the conversion. Until then a licence is not required in UK airspace.

The training for the LAPL(S) and SPL is identical - as are the examinations. The requirements are:

• 10 hours of dual instruction.
• 2 hours of supervised solo.
• 45 launches and landings (their words not mine!)
• 1 solo cross country of 50 km or a dual cross country of 100 km.
• Pass the theoretical exams.
• Pass a flying skills test.

All instruction by an EASA FI and the examinations and skills test by an EASA FE. Same basic rules as for the PPL.

Yep, that's the one. To add, the only real difference between the LAPL(S) and SPL is the medical. SPL requires a class II, just like a PPL, where the LAPL(S) medical requirements are more at the NPPL/LAPL(A) level.

I haven't kept up to speed with the EASA glider stuff. I have a silver 'c', would it just be a case of sending off the for the new license jobby?

Edit: and a class II medical.

Thing, I just checked the BGA website. Two things.

If you have at least bronze plus an x-country endorsement the BGA office apparently will issue you an ICAO compliant license right now. Or at least some paperwork saying you meet the ICAO requirements, or something like that. This is needed in case you go gliding in a country that does require a license.

Further, there is an FAQ on future licensing that is fairly vague at this time, but promises that everything will be sorted in the near future, including the process to obtain the license.

EASA Licensing

Thanks for that BP.

Conversion rules from BGA certificates to EASA licences are not yet published because they need EASA approval. With a Silver C it should not be a big issue. There should be more information available by Easter.

What an excellent answer. I have been testing engine failure landing with full flaps and it does not end well. What happens is the aircraft falls out of the sky during flare, because there is not enough energy. What happens is exactly as you said. I do not recommend flaps for engine failure, you need the inertia

you are correct about use of flaps in this case. In the sim the plane does drop like a rock in the flare, because there is not enough energy. The only correcting I would make is that you can never have less inertia. Inertia is constant, it never changes. What you might be referring to is the aircrafts momentum, I would say the aircraft has less momentum, and therefore less kinetic energy to convert into lift.
I might try approaching with a lower nose attitude, higher airspeed, to see if that helps. But based on what I found do not use flaps

13 years after the OP. there's a resurrection. Record?

Hey, if a poster found this thread after a search of the topic, and finds value in restarting the discussion, that's what we're here for!

Big Pistons is still a valued participant here, I chat with him from time to time, so we'll look forward to a contribution he might make here. He is certainly someone I listen to!

Some decades ago reactivating my CPL in a 172, we did forced landings off the circuit. You can flare power off with 40 flaps provided you have enough airspeed — best learned with an instructor experienced with the technique.

I am not your insurance company.

Yes, though the airplane will slow down very quickly when you raise the nose with more than 20 flap extended. I'm happy to see the flaps extended from 10 to 20 when the runway is "made" power off, and everything is stable, and then selected 20 to full as the flare is begun. If you time it right, it works fine, though this, as said, is best practiced under competent supervision. In a Cessna, a power off approach with more than 20 flap, other than close over the landing surface, is unwise.

If you are in the habit of starting flare at 30 ft and floating several hundred feet down the runway you may think that a full flap flare with engine idle is impossible without excess airspeed.

If you are used to making minimum energy landings I would not expect you to have any problem making a flare with full flap and engine idle. If you do, check the CG position and adjust it further aft as required to increase elevator authority. A case of drinking water at the aft end of the baggage compartment does wonders for the flare characteristics of some types. A jump master moving to the back wall of a C-182 jump plane is just as beneficial.

My current ride has 46 degree max flaps and they are very effective. I don't have a problem with idle power flare to 3 point landing but the flare starts quite close to the ground and the approach is a lot steeper than 3 degrees.

Know your aircraft and, if you don't know it well enough yet, move incrementally closer to the corners. You may be surprised what it can do.

Didn't have a good number to quote so I ran a test point today. Full flap, throttle idle, airmass FPA about 7.5 deg at my typical approach speed of 45 kt. Approach pitch attitude 2-3 degrees and 3 point attitude on level terrain is 12.5 deg so about 10 deg pitch change in flare.

Yes, it's a lot different from the typical flat flare done by many nose dragger pilots at the end of a dragged in approach.

Legally that's probably right.
Practically, it's not. In a 30 kt headwind with a 60kt best glide speed, where are you going to land?

Absolutely! I suspect there is no simple answer to this, but that the "best speed to fly" is somewhere between speed for min rate of decsent (to maximise time in the air if you are already over landable terrain, which might be with a small amount of flap) and the speed for best glide (to maximise range (which will depend on relative wind speed and direction). A headwind is very useful for the landing itself but will certainly steepen your glide path and limit how far ahead you can reach. Provided you have enough height, and you know that the terrain downwind is generally landable it might be best to fly downwind close to speed for min sink to maximise ground coverage to select the best landing spot (bonus: this also places you nicely on a downwind leg for your "circuit"). Conversely if there is a runway straight ahead into wind which you think you can reach (given the headwind) then flying above the manual's quoted best still air glide speed will increase the gliding range.

The above is very much the personal view of a glider pilot, and whilst I used to also have a PPL was fortunate to never have an actual engine failure- but that is how I would have handled one!

One of the things I train is that I would rather do a decent job of making a poorer close forced landing site, than a poor job of reaching a better one. If you have any need to stretch a glide, that means that prior to the "event" you chose to fly over territory which was lees suitable for a forced landing. Sure, we have all done it, when our confidence about the airplane was good. And, I have certainly remained over suitable areas the whole time when I was not confident about the engine! Remember, if you have to actually force land power off, you'd rather misjudge and go off the far end at 20 MPH, than misjudge, and crash short at 65 MPH! I want my students to choose a good enough close spot, and make a good job of getting into it. So, for me, "best glide" will be a brief period, usually right after the failure, while you diagnose, and choose your [nearby] spot. After that, though we won't waste a glide, I'm happy to see an approach set up which includes a lesser flap setting and a sideslip to get it. You can always undo a slidslip to recover more glide, you cannot retract flaps to do it! So, for me, any flap use for a power off forced approach will be very late on the approach, but then, as much as possible to shorten and slow my ground roll.

I have had four power loss forced landings over the years. I have been very lucky to have never damaged a plane doing it. But, I have been right up to the far fence a couple of times!

Most of the replies so far have concentrated on achieving maximum range during the glide. But one day I found myself 4 miles from the airfield at 8000ft, so needed to reduce altitude quickly. The plan was Full 40 degree flaps and fly just below 80 knots by pushing the nose down. It worked very well maybe 3000 fpm+ descent rate.

Also for all those glider pilots amongst us, Full Airbrakes and side slip usually gives a glide slope of over 45 degrees.
Hope this helps, in case you ever have too much altitude.

Yes, you can do a full flaps Vfe descent. That wouldn't (hopefully) be in the context of an engine failure, but it can be done. I wouldn't do a 3000 FPM descent with passengers aboard, they'll probably decide to not fly with you again! Just remember that if you do that, and then actually have an engine failure while you're doing that, with full flaps already out, you've configured the airplane for the least good glide if you needed to. Setting up a base to final to flare with full flaps extended will take an extra layer of skill!

For years I fly jumpers, where a similarly fast descent was desired, I preferred to carry some power (to prevent shock cooling) and orbit down flaps up at a faster speed, A bit of G in a turn (if you're by yourself) will increase your rate of descent. That way the airplane is already set up in a good configuration for a glide if there is an engine problem.

And, for "normal" flying, a Vnav calculation....

I was right seat in the Twin Otter doing a ferry flight in 1985, and doing the radio work. We were number umpteen to land behind a long line of jets in Cairo. We were at 6000 feet approaching the airport. My Captain was a retired deHavilland test pilot. Cairo tower called me, and said that they had a break in the approaching jet traffic, if we could be down and clear in two minutes, we were cleared to land right now. I asked my Captain... As he reduced power, and smiled, he said "Yes". I accepted the landing clearance. The power smoothly came back to idle (PT-6's don't care about shock cooling), the plane slowed, the flaps went down as we continued to slow, and the nose went down, Then I felt the "braking" force, as he pulled the power levers into Beta range, and we rode some reverse all the way down to a nice landing - we were down and clear, from 6000 feet in less than the two minutes offered - not normal flying!