Impossible Turn

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MrMorden
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Re: Impossible Turn

Post by MrMorden »

FastEddieB wrote:
MrMorden wrote: Everything I have seen regarding making the turn at marginal altitudes says the turn has to be made immediately and aggressively.
Aye, there's the rub.

Real pilots in the real world facing real unexpected engine failure do NOT generally act immediately.

Any instructor will confirm this.

I think the mental process is, "What? Huh?? REALLY??? Cripes!!! Need to act RIGHT NOW!!!"

Typically 3 or 4 seconds. Maybe 2 if you're really, really sharp and practice it all the time.

In any case, plenty of time for speed to bleed off and options to gradually disappear.

Again, my plan will always be to find a least bad spot ahead of the plane with no more than about a 45º turn required and get established towards it. Then, and only then, with the speed good and the plane configured and trimmed, might one weigh the option of another turn back towards the runway environment. Its when that decision is rushed after the almost inevitable airspeed loss that bad things often happen.
Having not been in that situation I can only guess, but I assume my "deer in headlights" time might be at *least* 4-5 sec. I usually thing of my turn to crosswind (700 AGL) as the minimum height to even think about that turn.
Andy Walker
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2007 Flight Design CTSW E-LSA
SportPilot
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Re: Impossible Turn

Post by SportPilot »

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Last edited by SportPilot on Sat Nov 08, 2014 7:39 pm, edited 1 time in total.
3Dreaming
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Re: Impossible Turn

Post by 3Dreaming »

SportPilot wrote:If too high, you would use various techniques to get down such as S-turns, slips, or WHATEVER IT TAKES. My point is, it is often quite possible to make a 180 and land without being at 1000 agl. Many times, landing on the airport environment is better than landing straight ahead on top of a heavily populated area, etc. If you're too high, make a 45 to the right followed by a 225 to the left.
It is not about being to high, it is about being to close. By the time you get the turn made and lined up there will not be any runway in front of you. to change your heading and be lined up with the runway you will need to turn more than 180°, probably closer to 270°. If you are turning 270° with turn reversals you could likely turn 360°. If you are still over the runway I think this would be a better choice if you have the altitude to make the 360° turn, because you will wind up back over the runway with any runway you had in front of when the engine quit still there.
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CharlieTango
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Re: Impossible Turn

Post by CharlieTango »

If an immediate steeply banked reversal of course is the called for reaction, given adequate altitude, how is it that doing so ( In a CT ) means you will be too high and run out of runway possibly with a tail wind.

My home field plan depends on the runway.

9, I want 600' AGL and I will put the nose down and turn left crosswind, assuming I got to the end of the runway. Next I need a right 270 and the terrain is falling away, a wide enough opening for the 270. This plan provides for my descent beyond the runway and there is no fear of overshooting the field.

27, The terrain is rising and hostile, most likely I would side step to the left and land on the highway. Loss on right crosswind would be hard to get back and not overshoot.

I use 9 most of the time.
Wm.Ince
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Re: Impossible Turn

Post by Wm.Ince »

This is an excellent discussion.

So . . . . . assuming calm winds and a pilot reaction time of 5 seconds, I would like to ask Prof. Shuch and experienced light sport pilots . . . what would be the ideal altitude and minimum runway length for a turnback to be practically considered?

My point being, perhaps a "go/no go decision point" could be calculated (minimum runway length and an associated minimum altitude at the end of it) for any given runway in a light sport airplane.
Bill Ince
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CharlieTango
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Re: Impossible Turn

Post by CharlieTango »

Wm.Ince wrote:This is an excellent discussion.

So . . . . . assuming calm winds and a pilot reaction time of 5 seconds, I would like to ask Prof. Shuch and experienced light sport pilots . . . what would be the ideal altitude and minimum runway length for a turnback to be practically considered?

My point being, perhaps a "go/no go decision point" could be calculated (minimum runway length and an associated minimum altitude at the end of it) for any given runway in a light sport airplane.
As I said above I use 600' AGL for the friendlier runway and I use that altitude to retract my take-off flaps. To me the flap retraction is a signal to be ready to turn back and might cut my reaction time.
Wm.Ince
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Re: Impossible Turn

Post by Wm.Ince »

CharlieTango wrote:
Wm.Ince wrote:This is an excellent discussion.

So . . . . . assuming calm winds and a pilot reaction time of 5 seconds, I would like to ask Prof. Shuch and experienced light sport pilots . . . what would be the ideal altitude and minimum runway length for a turnback to be practically considered?

My point being, perhaps a "go/no go decision point" could be calculated (minimum runway length and an associated minimum altitude at the end of it) for any given runway in a light sport airplane.
As I said above I use 600' AGL for the friendlier runway and I use that altitude to retract my take-off flaps. To me the flap retraction is a signal to be ready to turn back and might cut my reaction time.
Thanks CT . . . point well taken.
Bill Ince
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drseti
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Re: Impossible Turn

Post by drseti »

Wm.Ince wrote:what would be the ideal altitude and minimum runway length for a turnback to be practically considered? .
As Charlie Tango's post suggests, that is highly dependent upon your particular airport and its surrounding terrain. If going out of an unfamiliar field, talk to the local flight instructors about what options they would consider. If flying into an unfamiliar field, scope it out first on Google Earth, to see what your landing options are off various runways. If you do want a hard and fast rule, make it very conservative. (I tell my primary students that, starting out, they shouldn't even consider the turn-around below 1000 AGL. Those personal minimums get reassessed and modified periodically, as the pilot gains skill and experience.)
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
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dstclair
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Re: Impossible Turn

Post by dstclair »

I can't find the article but I read a fairly thorough analysis of the Impossible Turn that had both theoretical and practical data. Key fact of the article was that a 60 degree bank turn at best glide speed provided the shortest route back to the runway with the least altitude drop BUT it would be dangerously close to the stall speed so a 45 degree bank should be used. This provides an extra cushion of safety with minimal impact to the efficiency of getting back to the runway.

I think most of us are saying the same thing -- have a plan for engine failure every time you take-off. It should be a simple decision tree that is based on your altitude after your "Oh S***" moment. My personal one:

Runway 17:
* If below 1600 MSL, aim towards golf course and pull chute
* If above 1600 MSL, return to runway

Runway 35:
* If below 1450' MSL aim towards pastures and pull chute
* If above 1450' MSL, return to runway

T31 is at 790' MSL.

The different altitudes are possible due to a somewhat unique runway arrangement at T31. The runway consists of a 3000' asphalt component (south end) and a 1400' grass component (north end). So one could essentially undershoot a turnback by 1400' if taking off to the north.
dave
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