Turnbacks
 

Just to clarify what I mean by "turnback" it's where following an EFATO (pretty much by definition in a single engined aeroplanes) the captain elects to try and return immediately to the take-off runway, landing in the downwind direction.

I've only ever attempted them under (relatively) safe conditions, for my own interest - generally it's left me with a clear view that it's not a manoeuvre I'd attempt under most circumstances. I've however quite a few times had occasion to observe the consequences of a turnback - which invariably seems to have involved destruction of an aircraft (although rarely loss of life).
Working on analysis of yet another case (and yes, yet another destroyed single engined aeroplane), I've been pondering. Has anybody ever done some serious formal research on the turnback? - how best to fly it, go/no-go criteria, relationship to aircraft characteristics? If so, can anybody point me at any publications describing formal turnback investigations?

This is, I should emphasise, pretty much just personal interest in the topic - not any particular case (yes I am working on something at the moment, but no the turnback performance wasn't really relevant to the outcome and anything I learn now will almost certainly have no bearing at-all).

For that matter, is anybody (well, any full time aviation organisatio) anywhere in the world still advocating turnbacks as a standard post-EFATO action?

G

Ahh, I'd forgotten starting a thread on this five years ago (grief, I need to get out more):

http://www.pprune.org/forums/showthread.php?t=66757

However, I don't think it changes my current interest.

G

Transport Canada has been active on this subject, and there is a civil aviation document TP13748E 'An Evaluation of Stall/Spin Accidents in Canada 1999'. It's referred to on the internet in the context of turnbacks, but it's not explicitly available on-line - so it's a suitable challenge for a university library...

I have in my papers somewhere an early 1990s Canadian article on turning back, which contained some numerical analysis and proved to my satisfaction that turnbacks were all but impossible. Now I regard even tree-tops ahead as a better bet.

I shall not rest now until I have found it, and when I have I'll send it to you.

Graham P.

Turboprops
 

I believe the PC 12 operators look more favourably on the turnback situation due to the better rate and angle of climb of these aircraft, giving a better margin. Obviously there must be a minimum turnback altitude, but in some situations it would be less suicidal than it has been in the past.

This a topic that crops up frequently in the GA press, and I well remember writing to Pilot magazine in 1993 in response to a long article that proved it was an impossible manoeuvre!

My only experience of them is on my UAS days flying Bulldogs. It was a standard training exercise for the more advanced students (I was doing them from about 40 hours), and the QFIs were tested on them during their trappers visitis, I seem to recall.

It was only advocated for runways where an EFATO would put you into the spare bedroom of 13 Acacia Avenue! One of the key elements was that it was part of the T/O brief, so was not a spur of the moment decision, and the direction of turn would be briefed as into any crosswind, to minimise the turn radius. The absolute lowest height to attempt it would be 450 ft agl and the aim was to return to the airport environs first, land back on the reciprocal runway, second.

The actual handling of the manouevre required precise and prompt input, and as I recall was something like this (20 years old memory so bear with me!):

• Smartly lower the nose to 'nail' Vy
• Transfer to instruments and roll to 45 degrees of bank
• Maintain an accurate Vy and 45 degrees on instruments for the first 90 degrees of turn
• After 90 degrees of turn, ease bank off and visually assess likely landing site
• When lined up/wings level consider some engine shutdown drills, but concentrate on the landing

I seem to recall there may have been mention of flaps to 'inter', and even 'nibbling the light buffet', but can't swear to it.

One thing is for certain: if an average PPL decided on the spur of the moment, following an EFATO, to attempt the manouevre, without any prior practice or training, it would most probably end in tears!

I imagine the problem it forcing yourself to fly fast enough with the ground rushing up. Should brief what parts of the airfield or surroundings are landable, just because you took off from a paved runway doesn't mean you have to struggle to get back there. I'm only an ex glider pilot from a big field so I usually had options. Important to pull the cable release not the airbrake in the heat of the moment though :ooh:

Damn you guys are good!

That paper by David Rogers is printing as I type - something to read over lunch today I think, and I shall try from my end to get hold of that Transport Canada document.

A note to 212man; the RAF I know used to teach turnbacks as a matter of course. I think that these were finally killed off circa 1994 after a Hawk with a QFI+QWI crew with about 6000 hours between them landed on a wingtip at Valley at the end of a practice turnback. This led to the realisation that HMQ was losing more jets practicing turnbacks than she saved by having crews current in the practice and I believe they were banned. I'm not sure how this related to Bulldog practices (possibly your local OP was based upon minimising risk to third parties?). But, one point you mentioned rings true with my own experiments - I've found that nibbling the stall warning always gave the least poor chance of getting away with it. That seems to be borne out by the conclusions in Rogers' paper too, who advocates turning at 45° of bank and 5% above the stall speed in the turn.

G

GTE, the paper bears out the practice nicely. I last flew one in 1987, so not sure what happened later, but it wasn't a local procedure, as far as I recall.

Bearing in mind that by that stage we were 'spin/aeros' checked and were familiar with sensing stall bounderies (without a warning buzzing away in your ear: disabled) I'm fairly sure now that we were taught to 'nibble the buffet'. Not all students were taught and it wasn't in our syllabus, but certainly the QFIs were expected to remain current.

Quite, one of the reasons for going to instruments for the first half of the turn a) minimise height loss by flying accurately b) minimise risk of stalling!

The intent was not purely to get to the runway, and it would not be contemplated if there were decent areas beyond on which to force land (as there were from some runways.)

An observation there. I'm not sure that I remember the Bulldog's stall warning ever being operable - but it did have fairly clear natural stall warning. That may however not be true for all aircraft.

G

Having started off on the Vigilant (Grob 109) we were taught turnbacks but they were:

A. planned out for each runway and shown during briefing- 2 runways so four directions that were:

B. graded specifically on height and wind speed direction at the point of EFATO e.g. minimum 300' still air, min 500' wind above 10 knots.

C. as an FSC I was once made to carry through a practice turnback and land in a light tailwind to show it is tricky.

D. captain's discretion - you were not expected to slavishly follow them if it was gusty for example.

E. I'll have a look but the FRC's refer to using the MINIMUM angle of bank to minimise height loss something like 10-15*.

F. I found it very hard not to perform an immediate turnback when I started on the PA28 - those drills were still a sharp instinct 8 years on!

G. Feather the Prop in the subsequent actions.

It was disabled, hence my comments about being able to judge stall bounderies without the aid of something whining in your ear.

What an excellent thread, enjoyable read and the pdf document link is excellent too.

I'm part-way through an FI course. The turnback was a demo and practise on my pre-course entry 'test'; and it's been done once more at the end of one of my air exercises both at height, and in the circuit.

My FI instructor wants me to experience the turnback for two reasons: to sharpen my handling skills; and so that I can talk from a position of strength to my students to give weight to what will be my advice of 'don't try it'. Fair enough.

It'll never, ever be used by a PPL with any success. The vast majority I'm sure won't have the handling skills, or presence of mind to do one successfully. More to the point there's no performance data in the flight manuals regarding turnbacks; there's nothing like the CAA Safety Sense leaflets for turnback guidance (these UK CAA leaflets are great for giving you factors to apply in a variety of take off and landing scenarios) which would give info such as increase airspeed by 'x' or never exceed bank angle 'y' or perhaps most importantly, what to do in wind. The above pdf is great for aero engineers like myself or Genghis, or tp's or the very rare flying techno-anorak. But a ppl won't go anywhere near it - nor will most FI's.

The turnback is all-or-nothing. If you don't get back to the field with it you're arguably in a much worse position than a crash straight ahead. Ground speed in any sort of wind will be greater. Eg in a 10 knot wind I'd rather crash straight ahead at a groundspeed of 30 knots (I fly a DHC-1) than turnback, fail to get to the field, but crash at 50 knots -

Most definitely a potential 'killer', one of the major problems being the loss of airspeed going from a headwind to a tail and the tendency to stall in the turn therefore.

Nothing wrong, with a QFI onboard to show you what it is like, but keep the carb heat on and a hand on the throttle:eek:

As D120A and others say, there is normally a better option ahead, +/- 45 deg, unless you are in a high-power machine when you may well have enough altitude. They were always exciting in glider training after a lowish cable break.....................

212man, your recollection of the Bulldog turnback drill isn't quite correct. (I still have my QFI CFS lesson plans and copy this directly from them):

Under the "Stalling in Manoeuvre", Advanced Turns (2).

(6) TURNBACK (n.b. This being the final part of the lesson)

LOWER NOSE TO 80 KT ATTITUDE
SMOOTH AND POSITIVE 45* ANGLE OF BANK
LEVEL WINGS ON RECIPROCAL
FLAP A/R
MIN HT 350' AGL.

I think at Vy you might well come a very nasty cropper, hence this being included in the "Stalling in manoeuvre" sortie.

Yes, we used to practice them and be standardised on them; I used to brief EFATO drills for every takeoff and although the turnback option (or not) was included in the brief, I would be reluctant to do one for real if there was any other option.

BOAC wrote:

There's no loss of airspeed turning out of a headwind to a tailwind. If there were, you couldn't fly a 360 at height without constantly changing attitude to maintain a constant speed, 'cause there's head and tail wind there as well.

However, if you turn back in these circumstances your groundspeed increases markedly (by 2 x windspeed once you've completed 180 degrees). As all this is happening close to the ground, and is thus very noticeable, the natural tendency is to pull off the apparently excessive speed. Result, tears all round.

At height you don't notice the apparent speed change in relation to the ground, and so this doesn't happen.

A bit sweeping and does not apply if you change heading very rapidly. The numbers matter.

JF

I have a couple of links to papers by Rogers on the tech log sticky which may be of interest ..

Ask the RAAF
 

During 2FTS the RAAF used to brief the manouvre for every T/O in the Macchi. I don´t remember the details - maybe someone Dunnunda in Godzone knows. I wonder if the RAAF still do turnbacks in the PC9 or Hawke?

PITHBLOT

Some time ago on the RAF Hawk, we briefed turnbacks at Valley, but only after achieving a minimum of 250kt - and also Valley was fortunate in having an alternate runway not too far round from the main.