Turnbacks

[Genghis the Engineer]

Now before anybody gets worked up, I'm not advocating this manoeuvre, just discussing it.

Flying with a friend last night in a PA28-161 he introduced me to an interesting exercise. Setting up a simulated initial climb-out at a safe height for stall/spin recovery (we used 4,000 ft) - in my case this was 65 KIAS, full power, 25° flaps setting initial heading on the DI bug, we tried simulating an engine failure and turning onto the reciprocal, excercise being completed with Full flaps being selected as I rolled out on the reciprocal heading.

I did this a few times, and unsurprisingly my best result (a 250ft height loss) was nibbling the stall warner at 73 KIAS best glide speed all the way around a 45° banked turn. Every other time, including attempts to repeat that result I used up 400 ft.

It hasn't done a great deal to change my view on turnbacks - still think they're difficult and dangerous but, if say I was taking off straight over water or forest, it indicates to me that above 600ft it would be an option (in this type), although not below.

Thoughts anybody?

G

[foxmoth]

As you say, an option when you have nowhere else to go, though even the water may be the better option. Places like Southampton where you are straight over a built up area are the ones I would consider this. If you ARE going to look at this manouver then DO practice at height and also PLAN to use it when needed, don't wait until after the failure to decide where to go.

[Shaggy Sheep Driver]

Another point to bear in mind is the surprise factor. When it is being practised as an excercise, you set up the aeroplane in climb-out configuration, settle yourself down, then 1 - 2 - 3 GO!; power off, nose down to the right speed, wind on the bank, pull to the nibble, reverse the turn, roll erect (don't forget a simple 180 isn't enough - to regain the centreline you need to do a tad more than a 180, then reverse the turn).

If it happens for real, the chances are you will lose vital seconds before you realise *yes - it has actually happened*, by which time the speed will have bled off a bit so you'll have to stuff the nose down smartly.

Result? - If it happens for real, you'll likey have less time, and less height to play with than you did when practicing. That 400 feet could easily become 600 feet or more.

But it's an interesting one. Must give it a go and see how the Chippy performs it.

SSD

[foxmoth]

Sod the centerline, anywhere on the airfield, or even off it if flat will do me!:eek:

[Field In Sight]

I mainly concentrate my efforts on making sure I have done my before take-off and power checks properly. This considerably reduces the chances of the engine stopping on take-off.
I trained in Long Beach, CA and most of the time after take-off you just tried not to think about it too much. As there were very few landing sites.

During the climbout I do all the normal things like maintaining airspeed, runway track etc but what I think I should be doing is constantly picking landing sites so that if the engine does stop, I already know where I'm going.

Something like.
1. Runway still ahead, I'll land there.
2. Not enough runway ahead now, but I can land on the intersecting runway.
3. Not enough runway now, I'll go in that field over there on the left.
4. Can't make that field now, so I'll have to use that one etc,etc.
Do this until turning back is a safe option.

I'll give it a go, the next time I go flying.

[FormationFlyer]

Well my thoughts are....

Turnbacks are safe given an appropriate amount of height.

You *must* pull to the nibble of the stall in order to get the max rate from the turn. Anything less is wasting distance in the turn...most raf chaps will be familiar with buffet flying - if you arent get a suitable qualified instructor to show you this...aerobatic instructors are a good bet here...

The calculations for stall speed in the turn that a lot of people quote are flawed - almost all stall speed in the turn calcs rely on maintaining level flight...

Basic instruction behind not turning back is IMHO correct. The point is that there is NO decision to make...the last thing you want is someone um'ing and er'ing about whether or not to turn back...if the basic response is EFATO then they are more likely to survive...incidentally if you have enough time to think about this having set up the EFATO then you are getting close to a safe enough height - if you dont have time to think you are too low for turnback...

---

Must say I am curious now about say 60-70deg bank + pull to buffet - to see how much height a pa28 would actually lose - could come in handy one day...next time im on my own I will give it a try and see what happens (safe height first obviously + HASELL just too make sure I dont meet anyone else in case I get it wrong!)

Interesting...

[Whipping Boy's SATCO]

The RAF went through a phase of bending many aircraft (and a few fatalities) just practising this manouevre.

My personal view, only if there are No other options.

[Windy Militant]

Another point to consider is the considerable increase in drag that occurs in a real fan stop. This has been mentioned by several people who have actually had to do it for real. A windmilling prop is one hell of an air brake. I wouldn't like to try this as an exercise but It would be interesting to know how much extra height loss that this would incur.

[QDMQDMQDM]

Surely, where conditions for successful forced landing are unlikely the best thing to do on a standard takeoff would be to start a gentle climbing turn at 50 feet to circle up over the airfield before reaching a safe height to leave the area?

I realise ATC mostly isn't geared to this, but where options are limited, this has to be the best solution, doesn't it? Shouldn't controlled airfields with limited forced landing options (particularly built up areas) review their procedures?

QDM

[Rod1]

Glider pilots are taught to plan what to do before takeoff. Wind is x so up to a I will land ahead, above a up to b I will circle left and land, above b abbreviated circuit and lend, etc. This training meant I was turning back after an engine failure almost before I had registered what was going on, and probably saved my neck.

FIS

“mainly concentrate my efforts on making sure I have done my before take-off and power checks properly.”

I subscribed to this, but Crank failure does not show up until it lets go, same probably true of other things.

WM

“Another point to consider is the considerable increase in drag that occurs in a real fan stop.”

This is considerable!

The factors, which make a turn back work of fail, are many and varied. Wind is probably the largest semi unknown, and it can be completely different at 500 feet to what is shown on the windsock.

[Croqueteer]

In a Condor a few years ago, I did some experiments gliding engine off, prop windmilling and prop stopped, and the difference was only about 100ft/min worse with a windmilling prop. Try it. Also, even a Pitts will do a 180 turn back in 200ft, but I covered all this about two months ago. I am glad to see people actually investigatig what their aircraft will do. (At a safe ht, properly pre planned)

[EI_Sparks]

Avweb article on this (http://www.avweb.com/articles/turnback.html)

[bluskis]

Turn back can work out OK.

My experience was as a passenger in a Miles Messenger climbing out of Bembridge over the sea when a connecting rod went through the side of the crankcase. Needless to say the cause was only known later, however there was a horrible rattling noise and vibration, we turned back and landed fast, long and just stopped before the airfield boundary.

That day we used six different forms of transport to get home. Somehow even a bicycle came into the equation.

I guess the answer is you do what you have to do.

That was the first of 5 partial or full engine failures I have experienced in light aircraft over the years, plus two as a passenger in commercial airliners, information I was going to post in another thread where someone rudely questioned another poster who had had a number of engine problems.

I much prefer my engine problems to happen in a twin than in a single.

[englishal]

Another point to consider is the considerable increase in drag that occurs in a real fan stop
You're not wrong there. I remember my Complex endorsement training, practicing glides. Trim for best glide and we were still coming down at 1500'per minute. The instructor pulled the prop and we settled out at 500 or so 'per minute.

Its also worth remembering this if practicing glide approaches. I know of an incident, student and instructor glide approach in an Arrow. Prop was back, gliding in just nicely until the pre-landing check on short final of 'prop forward'. The aircraft landed so heavily that it nearly poked the wheels through the wing...the topside of the wing had two upward dents in it and had to be taken off for repair at great cost. Still, says something about the landing gear doesn't it :)

Cheers
EA:)

[Them thar hills]

Re the " more than 180 degree"comment by SSD I believe its a good idea to deliberately climb out off runway heading ( to the downwind side) so as to only have 180 degrees to get round if the engine fails. Any crosswind component would then compress the turn.
I've tried tight 180's at a sensible height in a Jodel and lost less than 300 ft.
But a Jodel has a light wing loading !

TTH

[Croqueteer]

Englishal, I think you are confusing the issue by refering to constant speed props, a totally different ball game.

[long final]

I watched a turnback from the overhead at BPL yesterday, it turned out to be a good choice, handled well, but with a near 10kt tailwind, EVERY inch of runjway (900m) was used.

LF

[Circuit Basher]

Apologies for dredging this one out of the archives, but had my own little practice of a part of the procedure last night:

Last night, when flying with a friend out of Kirknewton (1000m tarmac runway) in a C172 with virtually full tanks, as things were a bit quiet, I tried an interesting (to me, anyway!) experiment:

I tried to see if I could land with a 10kt tailwind! :) :)

May sound silly, but if one day I ever have an EFATO at a runway where there's little option for a straight ahead landing (such as off runway 21 at Perth, where there's about a hundred metres of very tall forest), I may have to consider the option of a turnback (the old and wise suggest that inexperienced PPLs / students may wish to get an adult to help them with this!!). This would logically involve coping with a tailwind landing.

Anyway, due to obstacles / high ground on the 06 approach (I'd departed on 24), I was around 200ft high / 75 kts over the threshold and had 40 deg flaps out. Only by really working at it would I have been able to get the wheels on the deck at the 800m point (200m left to run). My groundspeed at that stage was around 70-75 kts and my rudimentary recollection of the Highway Code indicated that my braking distance would exceed 200m, so I went around and landed in the 'proper' direction!! :-)

Landing roll for the 'correct' direction was around 300m without really trying (and only 20 deg flap).

I know this isn't very scientific, but thought I'd share this, knowing how often turnbacks are discussed.

[FWA NATCA]

The problem with "Turnbacks" is that most pilots attempt them at an insufficient altitude and end up crashing or landing well short of the runway.

If you do the research you will discover that many "Turnbacks" are unsuccessful because the pilot does not reach the runway.

As a controller another hazard exists because I may be launching another departure (or several) behind you, and if you make a sudden turn back things can get real ugly real quick.

As someone pointed out, with sufficient altitude a turnback is a safe manuver, but again the key is having enough altitude.

Mike
NATCA FWA

[Chimbu chuckles]

CB downwind landings are as common as muck in the commercial world...it's simply technique. While a bush pilot in PNG I regularly (like 10-15 times a day) landed on short, one way bush strips with significant tailwind components. Speed control and flightpath control are, of course, paramount. Less power at the same speed will give you a 'steeper' approach which the tailwind flattens out for you so it's all as per normal until the flare. An 'abbreviated' flare (best way I can describe it) will ensure you touchdown at the required spot and believe me you don't operate into fields where the LDA is short enough to cause a worry on rollout....unless you are landing on wet grass.

One spot I operated into with monotonous regularity was Garasa...380m, flat, rough and while two way I would regularly take 6-8kts up the clacker in an Islander rather than 'waste' time flying a circuit. My home base for a year was Chimbu where most afternoons brought 15kt tailwinds for landing...Chimbu was 1000m, sealed but one way due terrain. Elevation was 5000' amsl at ISA+20. We operated a C185 and BN2 there and the winds never slowed us down (forgive the pun:D)

Go out and do a few more and you'll soon get the hang of it. Remember speed spot on 1.3VS, power as req to keep the approach under control and don't hold off in the flare, just round out with speed washing off towards Vs, i.e. reduce power to idle a few seconds earlier, and instead of holding off just let the airplane land.

In general as far as turn backs are concerned they are very airplane specific. They work really well in the smaller Cessna singles but Pipers don't do them well at all. When current and practised I could turn a C152 around in < 150 and that after counting 1 thousand, 2 thousand, 3 thousand after simulated engine failure to account for the oh ****e factor. After that lowering the nose, slapping down full flap and rolling on 60 deg AoB and pull to the nibble had you around the corner before the flaps were 1/2 way down. As mentioned you are not attempting to maintain height just minimise height loss so wing loading is not as high and the flaps extending throughout the turn offset, to some extent increased stall speed and help 'balloon you around the corner'.

It's a very dangerous manouver and should only be attempted when well practised in the particular aeroplane and when straight ahead is a worse option. It's was also something I briefed before takeoff...never leave the decision until 300' on initial!!!

Chuck.

[Algy's Monocle]

I once fiddled around with a spreadsheet to investigate this scenario. I concluded from a straight-out departure, you need several thousand feet of runway beyond the rotation point. Otherwise, after the height loss in the turn, any expected glide ratio is insufficient to carry you back to the point of rotation.

Assume

Best climb of 60 kts = 1 NM / min = 6000 ft per min.
Climb rate: 600 fpm
Height lost in 180 deg turn: 300ft
(According to current wealth of experimental data: Thanks chaps!)
Glide ratio 10:1

1 Minute after Rotation
Dist = 6,000ft, Height = 600ft, Hgt after turn 300ft => gliding distance 3,000ft

2 Minutes after Rotation
Dist = 12,000ft, Height = 1,200ft, Hgt after turn 900ft => gliding distance 9,000ft

In each case the gliding distance is insufficient to backtrack distance covered – need another 3,000ft of runway beyond the point of rotation.

Neither light tail winds (10Kts), nor the trigonometry of 5 deg climb slopes materially affect the outcome.

...all rather academic, but stresses how difficult it is to make it back safely!

[Miserlou]

If you want to know the right answer, ask a glider pilot.

As one has already replied that they always have a plan of action which changes with height, I'd like to expand a little.

I case of an engine failure what you need is a decent flat bit of land. What you've just left was a very small 'licenced' area of what is in most cases a very much larger area of very suitable land which a rescue crew, can probably get to within three minutes or less. See the difference it made at Sioux City!

The plan you devize for your departure field may not require a 180. Maybe just a 90 degree turn to a cross runway. Perhaps a gentle 270.

Just as long as you maintain flying speed; and this is the big killer in GA, stall/spin accidents whilst making a forced landing.

[paulo]

New thread incoming...

Airfields with nasty approaches/climbouts

[john_tullamarine]

.. a couple of technical assessments by an academic are in the tech log URL sticky if anyone is interested ...

[Airbedane]

Turnbacks are not a good idea for the inexperienced or the faint hearted. Here's why:

I read a Boscombe Down report a few years (about 20) ago that implied that the minimum height loss in a glide occurs at between 55 and 60 degrees of bank. Now, with 60 degrees of bank, the load factor is 2, which means you're flying with 2 G on the aircraft. At 2 G the stall speed is increased by a factor of just over 1.4. So, if you're gliding at 1.3 VS, you'll stall, flick, spin, crash and burn before you've even started turning.

Trying to turn back at any other angle of bank will lead to too great a height loss, so again, it's a lost cause.

Turnbacks have been carried out successfully, I've even done one myself - I may even talk about it publicly one day, but not just yet! But, far better to plan the takeoff and climbout to use available fields in the forward sector in the event of engine failure. If there's no such field available, you shouldn't be operating single engine there in the first place.

A