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Return to reciprocal runway advised in emergency ?

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Old 16th Nov 2008, 15:29
  #21 (permalink)  

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Turn Backs

Shy Torque. In my RAF days onT33s in Canada we were taught to do a 90 degreees one way and then a 270 the other back onto the runway in use. Having said that I only ever taught straight ahead or up to 45 degres of turn in my later days.
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Old 16th Nov 2008, 16:50
  #22 (permalink)  
 
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While I think the 'never turn back' rule works well for training, in real life the decision depends on a lot of factors: altitude, speed, complete or partial loss of power, type of a/c, most suitable terrain, etc. In the case of both of my 'home' runways (one a big int'l airport, the other a small field), the best landing sites are definitely not straight ahead. There's also one other aspect to consider - according to some statistics compiled by the FAA, some 80-90% of EFATOs happen at the first change in power settings to the engine. So, at least statistically, not touching the power and/or prop lever until, say 1000 AGL (that's what I use as my personal level), should help.

On a different note, I find this advice
I was once told by an instructor that if taking off from a long runway, try to take off close to the end
completely mad! There's nothing as useless as the runway behind you and on a proper long one you might actually be able to land back straight ahead if it all goes quiet up front right after t/o.
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Old 17th Nov 2008, 14:54
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I have a simple rule for turnbacks.

If I pass 600~800 ft AGL on the upwind/crosswind leg I will try it depending on percentage of power lost and strength of downwind. Anything less than 500ft I'll consider it EFATO (look straight ahead for emergency landing)

Also I always keep in mind where the crosswind (if any) is coming from so that in case something go's wrong I'll turn towards wind to minimize the turn radius towards the runway.

In cases where the departure/pattern crosswind leg is downwind for the wind blowing that day I
A) try to delay a bit the 500ft turn (to gain height up to 700~800)
or
B) cheat the pattern (my ground track) off a bit towards to the direction of the wind blowing

... so that I can make it (glide) back to the downwind runway in case of turnback.

Choice of A) or B) depend on local topology like populated areas, terrain etc.

In the aircraft I fly (TB20) with gear retracted on downwind, abeam the touch down point I need 1200~1300ft AGL to glide to it.
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Old 17th Nov 2008, 16:51
  #24 (permalink)  
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I've researched this a bit over the years, and also did the ADR analysis as a young boffin on a Hawk which the RAF lost following a practice turnback.


It's clearly not a desirable thing to do, but it is noticeable that of all the people who have flown turnbacks, virtually none have ever been killed. On the other hand, virtually none ever got to use the same aeroplane again either!

To make it work, you clearly want to start right at the beginning end (not far end) of the runway. It's not going to work at-all unless you have a fair bit of height available and good visibility to see exactly where you've come from and where you're going.

After that, generally the approach that works is to turn one way first using maximum available roll rate, then fairly rapidly the other way (creating a "teardrop", turning right on the buffet all the way, at a reasonable speed and bank angle.

In still air, from an average runway, my experience (from experiments at a safe height) is that a typical light aircraft, with a very sharp pilot, might just get away with it from around 600ft, a slow microlight about half that, a fast jet 1-3 times that depending upon speed and stall margin at take-off. A good stiff headwind helps.


And with all of this knowledge, would I brief and attempt it? Almost certainly not - I can think of very few scenarios where I'd actually attempt the take-off, and landing ahead isn't a better option. Put another way, if landing ahead isn't a viable option, why am I attempting the take-off?

I understand that this manoeuvre is still taught to, and regularly practiced by UAS QFIs but primarily, I suspect, as an excuse to give them interesting flying and keep their handling skills sharp, than as a realistic emergency drill.

Finally echoing what PilotDAR said - plan it, brief it, execute it. Any pilot failing to brief appropriate emergency actions before take-off, or to stick to his brief in an emergency, is one I'd not care to be sharing an aeroplane with.

G
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Old 17th Nov 2008, 16:55
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Return to reciprocal runway advised in emergency ?

As a previous post mentioned, glider pilots do train for power failure on launch, in the preflight check mnemonic a last item `E `for Eventualities is included i.e. what do we do in the event, I am a gliding inst and tug pilot and as a tuggy I also add eventualities to my pre takeoff checks.

I think a little pre-planning might save you one day. worth a thought?
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Old 18th Nov 2008, 07:37
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When I learnt to fly back in the seventies we we were taught never turn back, in fact it was known as the "Pilot Trap".
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Old 18th Nov 2008, 08:15
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When I learnt to fly back in the seventies we we were taught never turn back
Exactly ! The very point I made when I started this thread !

But nevertheless very interesting indeed to hear the various different viewpoints and ideas which have been expressed. The really important thing seems to be the preparedness for whatever may happen, bearing in mind all the personal, aircraft, and geographical factors.
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Old 18th Nov 2008, 08:15
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What hasn't been mentioned is AIRSPEED. The pre take-off self briefing for launch failure with a glider winch launch goes.

"In the event of a launch failure I will lower the nose"

(Winch launched gliders are climbing at about 45 degrees nose up so achieving about a 30 degree nose down attitude takes a fairly significant control input)

"I will wait until an airspeed of xx has been reached" xx normally being the approach speed for the day which depends on glider type & windspeed and is well above normal stalling speed.

The accent here on waiting is that just because you have lowered the nose does not mean that you instantaneously have safe manoevring speed. Stalling speed during the pushover will be significantly below normal and any aircraft takes a noticeable amount of time to gain airspeed after lowering the nose.

"I will assess whether I can land safely straight ahead"

"If yes I will do so"

"If I am too high I will turn left/right" and reassess" - the turn is normally away from the airfield so as to open up the whole field for landing options and the options to be reassessed are a crosswind/downwind or limited circuit approach

And if a pupil doesn't run through that lot as part of the cockpit checks the instructor will almost certainly give him a "cable break" just as a reminder.

Note the stress however on not trying any form of turn until you've got the airspeed to do it safely. You'd have to be pretty far off the deck in a lot of powered aircraft!
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Old 18th Nov 2008, 16:00
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On my Spring Check a year and a bit ago, we were using 36 and had a good crosswind from the left; so, I told the checker that on a rope break above 300' I would turn right and land on 03 as the x-wind would set me up nicely.

Up we go and I'm calling out every 100' and pointing out potential landing spots; at my 300' call, the fiend in back pops the release; so, nose down, wait for 55 kt, turn, and start working the spoilers.

Turnbacks from 300' in a glider with 30:1 glide ratio are pretty straightforward. With your average piston single with 10:1 glide ratio, I'd want 900'.

Now there are courageous operators who do practise rope breaks and turnbacks from 200' in Schweitzer 2-33s -- not much margin there, nor would there be in a piston single at 600'. From that height everything has to be done just right.
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Old 18th Nov 2008, 17:15
  #30 (permalink)  
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Astir8

Light aircraft are differnt to gliders.

Your comments in your last sentence don't make sense for most aeroplane pilots, as we'd be climbing away at VS x 1.3 or a similar figure pretty quickly after lift off.
 
Old 18th Nov 2008, 17:37
  #31 (permalink)  

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I quote from my RAF CFS lesson plan (for the Bulldog, just dug it out from under it's dusty cover):

TURNBACK
Lower nose to 80 kt attitude
Smooth and positive 45 degrees AOB
Level wings on reciprocal
Flap A/R
Min height 350' agl
I have practiced from 350' (we didn't practice the landing, we only ever went around from a low position to avoid the risk of aircraft damage) and I certainly wouldn't want to attempt it any lower. By that I mean physically and positively beginning the manoeuvre, not thinking about it, or having a look. There were some practices where I said to myself "that would have hurt for real".

I would stress that the RAF taught the turnback as a last-ditch technique for where there is no alternative forced landing area upwind or crosswind and it's certainly not for the indecisive or ham fisted. Someone mentioned flying on the buffet. I wouldn't do that, a flick from 45 degrees AOB close to the ground would be irrecoverable. The 80 kts mandated for the Bulldog kept us just out of the buffet.

Once the surface wind picks up, the more likely I would be to discount the turnback option altogether.

I would advise anyone not taught turnbacks, or not in current practice on the aircraft type in question not to attempt it. Sometimes it might be better just to depart from an alternative runway in the first place, if there is a choice. Although you might land on the airfield near the fire engine, it could well be a hard, fast landing and possibly not on the runway. After all, who deliberately and regularly practices downwind approaches and /or landings?
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Old 18th Nov 2008, 19:51
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Final 3 greens wrote:

Your comments in your last sentence don't make sense for most aeroplane pilots, as we'd be climbing away at VS x 1.3 or a similar figure pretty quickly after lift off.
I think you would be surprised. A winch launching glider is normally climbing at more than VS x 1.3. If the launch fails, the pilot needs to push over immediately to around 45 degrees nose down, and it may take an appreciable time (2-3 seconds or more) for the airspeed to regain VS x 1.3. A delay of only a few seconds, if launch speed is VS x 1.5 or less, is likely to lead to a stall, though the climbing attitude is probably steeper than most powered a/c..

Now imagine a far draggier powered a/c in the same situation - I'd guess that at the top of the push over the airspeed might be less than VS (but reduced G so still flying), and maybe 5+ seconds to regain flying speed.

The only way to know for sure would be to try this for real (at height, obviously!). Adopt normal climb, stop engine (noting altitude as you do so), push over, pull out when flying speed is regained (again noting altitude). Add a margin to allow for slowed reactions if it happens for real.

The point is that I wouldn't rely on inertia to help you out for long in a climbing attitude if the engine stops, whatever your starting airspeed.
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Old 19th Nov 2008, 09:33
  #33 (permalink)  
 
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This is an interesting thread, but I am surprised no-one has talked about WHY turnbacks at low level are not taught/ recommended and I am also surprised that a number of people have alluded to the fact they don't do a pre take-off emergency brief (even if just for themselves).

I always take a few minutes to self-brief before take-off. I consider the runway direction/ length, wind, airfield, obstacles, etc. On take-offs I always have a look around so I am familiar with the "land out" fields, should the engine quit. Its much easier to spend a few minutes on the ground considering the options rather than in the air with a dead engine.

Part of the consideration is the turn back scenario. There is a base height, below which I won't turn back. This height will depend on various factors, including the wind.

On take-off the main reason turn backs at low level are not taught is that it is very easy to stall it and/or spin in. People make a shallow turn back, because the ground is near, and/or try to stretch the glide to reach the airfield and this often ends in an aircraft spinning in. Or people at very low level make a tight turn and hit the ground with the wing tip.

If you land straight ahead then you are in full control, you have flying speed and can influence where you land and how. Always consider an area within 30 degrees either side of the nose, aim for it then just keep the airspeed under control. You can then apply S turns, side slips, etc. as required. A controlled landing followed by running into a hedge or something is not gonna be great, but is survivable. A stretched glide where you stall and spin is probably not going to be.

Which is why the height before turn back thing is so dependent on aircraft type, conditions on the day, etc.

Someone said that why brief before take off because there are many things that could happen. Yes, that is true, but the only one that needs a quick decision is the engine quitting or a serious fire.

In my day job I fly an aircraft with 2 engines. If one quits it still flys. Yet we always always do a full emergency brief. This includes the initial actions if the engine quits, and consideration of which direction we are going if it happens (usually straight ahead, but could mean an emergency turn if there are obstacles straight ahead), and also we consider whether we would go and hold (and where) to sort out the problem, or if its a dire emergency (say engine fire) then we consider our options. If the wind is calm, or we take off with a tailwind then that could mean a 180 turn and land back, once we have sufficient height, or it could mean an abbreviated circuit. Alternatively, if the weather isn't great then we decide on an alternative landing airport that is nearby should we not be able to get back into the take off airport due to the weather.

All of these considerations are exactly the same considerations for light aircraft. The only difference is that there is usually only one engine!!

It might seem dull to brief before every flight but on the one time you need it, you will be glad you did it.
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Old 19th Nov 2008, 10:00
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Excellent reply Airbus Girl, was wondering if any one was going to say that.
One other item in addition is that you will be more than likely going from a headwind situation to a tailwind one and it will take a significant pitch down to maintain any airspeed, (which could mean a loss of 20kts and more so to maintain it in a 30deg bank) which at low altitude is going to be hard to have the courage to do as most peoples instinct is to keep away from the ground as you stated.
I often fly a Cirrus for recreation and it glides like a brick, so EFATO would be very entertaining to deal with especially out of Elstree
Totally agree with the briefing suggestion, like you we do it as a matter of course and when something happens you just get on with it.
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Old 19th Nov 2008, 10:26
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Sorry ,I'm confused.
You are doing say 60 knots airspeed with a 20 knot headwind,turn about and fly downwind.
You surely still have 60 knots airspeed?
The groundspeed will vary by 40 knots but not airspeed.
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Old 19th Nov 2008, 11:39
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Firstly you will have a high G/S on approach and touchdown which is going to reduce thinking time and probably hurt a lot more.
However, my point here is the need for instant momentum. The second you lose the thrust you will decelerate your G/S.

If order to have a 50 kt IAS in a 10 kt headwind your G/S is 40 kts.

In order to have an IAS of 50 kt with a 10 kt tailwind you would need a 60 kt g/s. Where are you going to get that momentum from?

If your stall speed is 45kt you will have a problem unless you accelerate your G/S.

G/S + W/S = IAS so 40+10=50 but with tailwind 40 + (-10) =30

so you need a G/S of 60kt to fly.

Where are you going to get that increase in momentum in a few seconds with a drag inducing windmilling prop in a 30deg bank turn.....only by pointing AT the ground, who is really going to do that?

An 'aircraft' will fly at zero G/S with a strong enough headwind, I have done it in a C150. However, if that wind suddenly drops to zero or a tailwind it will fall out of the sky. That is why you add a gust factor to the approach speed.

During the turn there is a point where you lose the benefit of yr 10kt H/W with the same or a decreasing G/S. You then (relative to G/S and direction) get wind from behind the wing (with an increasing stall speed power off/ banked attitude etc). But you still have to maintain the G/S IAS differential that keeps you flying.
Yes you will have some G/S increase due to the tailwind but that is not flowing over the wing enough is it until you have a groundspeed as in the example of 60kts.

My point is that you have a continuous acceleration in a turn from upwind to downwind which can only be achieved with a 'pitch steep' descending turn.


Best to land ahead

I would be interested in a discussion about this as there are apparently very different opinions.
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Old 19th Nov 2008, 12:16
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Pre take-off brief

I used to fly from a "challenging" 600yd strip, as a member of a group which I joined with a brand new PPL, 47 hours total. I remember my first take-off from the strip with a fellow member (ex-RAF, almost 10,000hrs as QFI) who was checking me out.

Me: "In event of engine failure, you have control!"
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Old 19th Nov 2008, 12:20
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Originally Posted by pilotbear
If your stall speed is 45kt you will have a problem unless you accelerate your G/S.

G/S + W/S = IAS so 40+10=50 but with tailwind 40 + (-10) =30

so you need a G/S of 60kt to fly.
Whilst airborne, groundspeed is irrelevant. Aerodynamics work irrespective of what the ground is doing (unless you collide with it).

I think that turning back on yourself is discouraged because it generally requires a high level of skill and judgement to execute such a manouver safely, particularly when under stress. When discussing launch-failure eventualities (I'm a glider pilot) the option to do a 180 in the event of a problem is always considered. That's where looking at things like windspeed, directrion, other traffic, etc. before you take off helps as you can assess and discount options and come up with a plan that you can execute WHEN a failure happens (and I always assume that it will).
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Old 19th Nov 2008, 12:31
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I was reading this thread yesterday and was reminded of a chapter in Alan "Bunny" Bansom's book, Be a Better Pilot, called "The Impossible Turn".
I looked at it last night and it's worth a read if you can get hold of a copy. His view was almost no matter what is ahead/to either side of you on take-off in a light aircraft, take it everytime over trying to turn back unless you are over 700ft. He supports this with various diagrams and equations which appear to show that it is indeed an impossible turn.
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Old 19th Nov 2008, 12:34
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Depends how high you are of course.

LAND AHEAD!! Only slight turns to avoid obstructions, that is the golden rule for us average pilots.

You will have a 90% chance of survival if you land "under control", I.E. flying and not stalled. Think of the increase in stall speed to pull off a 180 deg turn not to mention the extra rate of decent. If you have taken off into wind, which one would hope, think of the increase in G/S even as a percentage, on landing, trying to land on a reciprocal heading from a T/O as been mentioned previously. Have you ever seen a bird attempt to land downwind? No. So there is your answer.

Even if you loose the wings etc., on deceleration, it will help to absorb the impact forces. Just like a break fall in sport. The a/c will most likely be totalled but you will probably survive. The a/c can be replaced.

If you are in a turn and stall or dig a wing, you are dead, period.

I cannot speak for the Saturn V rocket but I have flown some high performance a/c and always pre briefed myself, "LAND AHEAD" within reason but never think about turning back.

I am talking powered flight here, as I have never flown a glider I am not qualified to comment.

Last edited by doubleu-anker; 20th Nov 2008 at 03:31.
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