To turn or not to turn

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Atrosa
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To turn or not to turn

Postby Atrosa » Tue Jan 01, 2019 6:37 pm

I'm still in my ground school (self study) and i read and watch as much as i can about flying. One recurring theme i hear is about power loss on takeoff. It seems that many times folks try.to make it back home and then with no power and a turn makes things go badly. I hear if you are climbing out and there is no power to find a place to emergency land but tragically many try to turn back. Please let me know your decision tree if faced with this horrible decision. Thank you in advance for your flying experience and wisdom.

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drseti
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Re: To turn or not to turn

Postby drseti » Wed Jan 02, 2019 12:25 am

The first thing to realize is that a 180 degree turn (which is frequently taught and practiced) will not put you back on the runway. It will put you parallel to the runway, offset by twice the turning radius. To land back on the takeoff runway requires a 270 degree turn (180 to get you parallel to the runway, an additional 45 to get you on the centerline, and then another 45 the other way to get you pointed back down the runway).

So, you need to do this experiment to find out how much altitude you'd lose in the so-called Impossible Turn:

First, climb to a safe altitude at least 2000 AGL over flat terrain, establish best glide speed in level flight with whatever flap setting your plane uses for takeoff, lined up over a road or other visual reference that represents a runway.

Next, simulate a takeoff by applying full power, rudder to keep straight, and maintain best glide speed in the climb.

Passing through a noted altitude, close throttle to simulate an engine failure. Now (this is important), do nothing for 30 seconds (that's how long it will take your brain to process what's happening in a real, unexpected engine failure.)

Now, maintaining best glide speed, roll into a 180 degree turn, at a bank somewhere between 30 and 45 degrees. Continue the turn for another 45 degrees to get you back to the road, and then 45 the other way to get you lined up with the road.

Finally, observe your altitude when you're back to the road and pointing straight down it. Figure out how much altitude you lost. That's your absolute minimum minimum AGL to attempt a turn-around in the event of an engine failure on takeoff.

You should repeat this exercise at various bank angles, to see if there's an optimum one for your particular aircraft. And, you should practice this maneuver (at altitude) from time to time, to make sure you can always nail that best glide speed, should you ever need it.

One final note: if taking off with a crosswind component, always know wind direction, so you can make that initial turn into the wind. This will keep you close to the runway. If you turn the other way, you'll just get blown further away from it.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
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Sling 2 Pilot
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Re: To turn or not to turn

Postby Sling 2 Pilot » Wed Jan 02, 2019 7:06 am

An excellent refresher Paul, many thanks!


drseti wrote:The first thing to realize is that a 180 degree turn (which is frequently taught and practiced) will not put you back on the runway. It will put you parallel to the runway, offset by twice the turning radius. To land back on the takeoff runway requires a 270 degree turn (180 to get you parallel to the runway, an additional 45 to get you on the centerline, and then another 45 the other way to get you pointed back down the runway).

So, you need to do this experiment to find out how much altitude you'd lose in the so-called Impossible Turn:

First, climb to a safe altitude at least 2000 AGL over flat terrain, establish best glide speed in level flight with whatever flap setting your plane uses for takeoff, lined up over a road or other visual reference that represents a runway.

Next, simulate a takeoff by applying full power, rudder to keep straight, and maintain best glide speed in the climb.

Passing through a noted altitude, close throttle to simulate an engine failure. Now (this is important), do nothing for 30 seconds (that's how long it will take your brain to process what's happening in a real, unexpected engine failure.)

Now, maintaining best glide speed, roll into a 180 degree turn, at a bank somewhere between 30 and 45 degrees. Continue the turn for another 45 degrees to get you back to the road, and then 45 the other way to get you lined up with the road.

Finally, observe your altitude when you're back to the road and pointing straight down it. Figure out how much altitude you lost. That's your absolute minimum minimum AGL to attempt a turn-around in the event of an engine failure on takeoff.

You should repeat this exercise at various bank angles, to see if there's an optimum one for your particular aircraft. And, you should practice this maneuver (at altitude) from time to time, to make sure you can always nail that best glide speed, should you ever need it.

One final note: if taking off with a crosswind component, always know wind direction, so you can make that initial turn into the wind. This will keep you close to the runway. If you turn the other way, you'll just get blown further away from it.

Atrosa
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Re: To turn or not to turn

Postby Atrosa » Wed Jan 02, 2019 8:13 am

I wish you instructed in CT. Everytime you post I learn. Skills combined with communication is rare.

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FastEddieB
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Re: To turn or not to turn

Postby FastEddieB » Wed Jan 02, 2019 9:40 am

Atrosa wrote:Please let me know your decision tree if faced with this horrible decision.


Good info from the professor.

It’s good to consider that if and when the engine goes quiet right after takeoff, one will generally not have time to go through any rational “decision tree”.

The general scenario is that there is roughly a 3 second delay before any action is taken. “Deer in the headlights”, so to speak.

During that time speed is rapidly bleeding off with the nose still high, so that by the time action is taken the plane can be precariously close to its stall speed. A turn back at that point is very, very risky.

Since there won’t be time for a “decision tree”, pilots need to be trained so that action is reflexive. And that reflex should be to firmly push the nose down and look for the best spot available straight ahead or within maybe 30° of the nose and head for it immediately. Once that’s done, headed for a decent spot and at best glide speed, possibly then a pilot may be consider other options, altitude permitting. That option might include a turn back to the runway, but usually not.

As an example of that, using the full length of a long runway, such as Knoxville’s McGhee Tyson, I can be 1,000’ AGL by midfield with any kind of a headwind. At that point I have lots of options, including flying a pretty normal pattern to land on the same runway. Which is a good reason to virtually always use the full length of any runway, no matter how long.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

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dstclair
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Re: To turn or not to turn

Postby dstclair » Wed Jan 02, 2019 10:12 am

And to add to Paul and Eddie's comments, have a plan before you take off for the specific airport/runway you are on. For my Sting taking off to the north at T31:

* If engine quits below 800' AGL, continue straight over the fields and pull chute
* If engine quits above 800' AGL, execute turn back to runway at 45 degree bank

AOPA did a study many years ago that proved the least altitude lost in a 180 degree turn is accomplished with the steepest bank. But this comes at the cost of a higher stall speed. The article concluded that a 45 degree bank was a good compromise between stalling and minimizing altitude loss. YMMV.

Also when you fly into an airport new to you, notice the environment since you will probably be taking off from the same airport later. This aides in coming up with you take-off plan.
dave

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joey4420
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Re: To turn or not to turn

Postby joey4420 » Wed Jan 02, 2019 4:05 pm

I know I went up with an Ercoupe CFI (well he owned an Ercoupe years ago and he was now a CFI). Anyways we went for a flight and while on downwind as soon as we went over the numbers (we planned this on preflight) I pulled the power at TPA 1700 feet, I was flying a very close pattern and making the proper radio calls indicating our plan. By the time I got over the runway my Ercoupe was at 900 feet and the runway is 630 feet, so I had 300 feet to spare and this was at 70 mph i.e. Best Glide speed in my Ercoupe.

So 1000 feet AGL would be minimum I would even consider turning back. Unless I am taking off runway 29 at HAO, then it is pray and turn or you will be hitting a building or trying to land on the road and missing the power lines.
Joey
Cincinnati OH
Sport Pilot
Ercoupe N99773

TimTaylor
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Re: To turn or not to turn

Postby TimTaylor » Wed Jan 02, 2019 6:39 pm

In reality, you would not make a 270 degree turn followed by a 90 degree turn the other direction. You would make a turn back toward the end of the runway which would be approximately 225 degrees +/-. When you reached the end of the runway, if you did, you would kick out the remaining 45 degrees of your approach angle, if possible, or land anyway you could. There are several factors that would enter into the equation including when you lost power, how quickly you reacted, wind direction and wind speed, runway length, your assent angle, and other options for an off-airport landing.

Calculating expected altitude loss is something I have never done, but is probably something each of us should do for each make and model we fly. I have often wondered why we don't make a 45 degree turn immediately after getting airborne and beyond the point of a straight ahead landing on the runway? If we did, in the event of an engine failure and turn back toward the runway, we would be lined up with the runway after a 225 degree turn +/-.

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drseti
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Re: To turn or not to turn

Postby drseti » Wed Jan 02, 2019 7:41 pm

TimTaylor wrote:In reality, you would not make a 270 degree turn followed by a 90 degree turn the other direction.


That's not what I advocated, Tim. What I said is 180 plus another 45, followed by 45 the other way, for a total of 270. So, we are in agreement this is a 225 degree turn in one direction, followed by a 45 degree turn in the other.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

TimTaylor
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Re: To turn or not to turn

Postby TimTaylor » Wed Jan 02, 2019 7:44 pm

OK, thanks.


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