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Q for any CFI regarding non-powered approaches. (Read 1206 times)
Apr 10th, 2011 at 3:01pm

Grant06   Offline
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After 13 years of regular powered approaches, throttle for altitude/ pitch for airspeed, I came accross the subject off non-powered approaches being safer as you don't have to worry about a power failure when on an approach. Currently been practicing this by just coming in fast, using gear, flaps and sideslipping to controll my desceleration. Is there more to this, or is it simply all about placing the runway in your windscreen in the right spot when you power down/idle.
How would a CFI tech this method of approach.
TY.
Paul.
...looking for something to work on today.

 
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Reply #1 - Apr 10th, 2011 at 7:32pm

Brett_Henderson   Offline
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You've got a good understanding of it..

The only "tools" I'd add, are the understanding that V-best-glide (for whatever your configuration) will obviously eat up the most ground, so obviously, any deviations (up or down) from that speed will steepen the approach...

Example.. coming in high, you could pitch for near Vmc (minumum controlable airspeed) and steepen the approach considerably.... OR .. Pitching for the highest airspeed availble (top of the white-arc when flaps are deployed), will steepen it too.

I prefer the latter, as hovering near stall-speed less than 1000agl makes me queasy (almost as queasy as slipping turns to final) , a significant wind-shift can erase your margin for error.
 
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Reply #2 - Apr 10th, 2011 at 7:56pm

Grant06   Offline
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Yes, I was thinking V plus 10kts on final with only 10 flaps (C182RG). Figuring you can always slow down if you have more flaps on hand, along with slipping.
Just wondering also, about dumping flaps just before the flare.
ty
 
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Reply #3 - Apr 11th, 2011 at 10:14am

Brett_Henderson   Offline
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Grant06 wrote on Apr 10th, 2011 at 7:56pm:
Yes, I was thinking V plus 10kts on final with only 10 flaps (C182RG). Figuring you can always slow down if you have more flaps on hand, along with slipping.
Just wondering also, about dumping flaps just before the flare.
ty


You'll get into a problem spot when you mix slipping and flaps.. depending on the airplane, of course.

While going against pulblished recomendations.. you can surely slip during a steep approach with flaps deployed.. we've all done it.. but the perils of my afformetioned wind-ship, become catastrophic. A high-winged airplane with flaps deployed is already "blanketing" the elevator.. a wind-shift at that time can render it utterly useless  Shocked

As for dumping the flaps just before a flare ? That depends on your experience-level, and confidence. If you wanna be brass-tacky about it.. a landing that would have you doing that, was a go-around before you got to that point.  Wink
 
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Reply #4 - Apr 11th, 2011 at 12:28pm

Grant06   Offline
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Brett_Henderson wrote on Apr 11th, 2011 at 10:14am:
Grant06 wrote on Apr 10th, 2011 at 7:56pm:
Yes, I was thinking V plus 10kts on final with only 10 flaps (C182RG). Figuring you can always slow down if you have more flaps on hand, along with slipping.
Just wondering also, about dumping flaps just before the flare.
ty


You'll get into a problem spot when you mix slipping and flaps.. depending on the airplane, of course.

While going against pulblished recomendations.. you can surely slip during a steep approach with flaps deployed.. we've all done it.. but the perils of my afformetioned wind-ship, become catastrophic. A high-winged airplane with flaps deployed is already "blanketing" the elevator.. a wind-shift at that time can render it utterly useless  Shocked

As for dumping the flaps just before a flare ? That depends on your experience-level, and confidence. If you wanna be brass-tacky about it.. a landing that would have you doing that, was a go-around before you got to that point.  Wink

Thanks for that. It just about seems like non-powered approaches is not the way to go. My original thinking came from a short talk with a CFII in regards to not depending on power for landing, but seems to impose more risks. Drafting the elevator doesn't sound good.
TY
 
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Reply #5 - Apr 11th, 2011 at 12:30pm

beaky   Offline
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Not a CFI, but I am a pilot who prefers to begin my final descent at a point and airspeed which will allow me to glide to my intended touchdown point without power if need be. To be honest, I tend to come in a bit high at first, but with flaps, spoilers, or slipping, one can steepen the approach without exceeding the desired airspeed or descent rate.

Of course, such "tricks" should not be necessary, if you know the glide characteristics of the plane and have a good idea what the wind is up to.

And in the end, landing a bit long or having to go around is better than risking coming up short... as my glider guru says: "Better to roll into the trees beyond the runway at 10 mph than to crash into the trees before the runway at 50 mph."   Grin


Granted, this is not an option with some aircraft, but in, say, a 182, every time you "drag it in" you are asking for trouble. Even a slight loss of power could make all the difference in such shallow approaches.

I see pilots doing this all the time- I guess they were taught to maintain a certain throttle/prop setting during final, so they come in shallow to stay at or below the target airspeed. That shouldn't be necessary in any plane that will glide 1 mile from 500-1000 AGL (which is most of them). Not surprisingly, the pilots I know who fly gliders do not seem to do this, even when they are flying twins or other aircraft that have fairly high approach speeds. But you don't need glider time to figure out how to do this, nor do you need to extrapolate any customized formulas from the POH... you just need to experiment and note the results.


 

...
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Reply #6 - Apr 12th, 2011 at 1:56am

Splinter562   Offline
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Good practice for this technique is the "Power Off 180" which is a maneuver for the commercial pilot practical. The basic goal is to make a spot landing when pulling the power abeam the touchdown point.

You have several tools at your disposal to tune your glide:
  • Time the base turn to compensate for wind.
  • Delay flap extension on base to compensate if low.
  • Cheat the base leg in or out to compensate for glide errors.
  • Cut the corner of the final turn if low. Overshoot the center-line by a little bit if high.
  • Delay flap extension on final to compensate for being low.


Like beaky said,  once you've got your eye trained into the glide you should be able to manage power-off approaches without any tricks. Timing your turns and flap extensions should be all you need.
 
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Reply #7 - Apr 12th, 2011 at 2:41pm

Grant06   Offline
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Splinter562 wrote on Apr 12th, 2011 at 1:56am:
Good practice for this technique is the "Power Off 180" which is a maneuver for the commercial pilot practical. The basic goal is to make a spot landing when pulling the power abeam the touchdown point.

You have several tools at your disposal to tune your glide:
  • Time the base turn to compensate for wind.
  • Delay flap extension on base to compensate if low.
  • Cheat the base leg in or out to compensate for glide errors.
  • Cut the corner of the final turn if low. Overshoot the center-line by a little bit if high.
  • Delay flap extension on final to compensate for being low.


Like beaky said,  once you've got your eye trained into the glide you should be able to manage power-off approaches without any tricks. Timing your turns and flap extensions should be all you need.


Thanks for that. Kind of what I was looking for. In other words put my brain on the approach abeam instead of on final. Turning can be used to adjust, not just flaps, gear, slipping.
Thanks.
 
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Reply #8 - Apr 13th, 2011 at 2:16am

Chris E   Offline
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Not a CFI here, but just passed the commercial single engine checkride at a school that emphasizes power off 180 approaches.  Only bit to really add is that it does come with the danger of unexpected turbulence, wind changes, especially wind shear, and so on and so forth.  Each of these may force you to add power.  So use caution while attempting these approaches.  They can be quite fun though and if you do the power off 180 style approaches can really improve your landing accuracy in general.
 

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Reply #9 - Apr 13th, 2011 at 7:40am

EVVFCX   Offline
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I try to base things loosely to when i was doing a lot of gliding.

Assume you have no guide to what your height should be: In the glider we were taught to try and get you final height such that you do your finals on half spoiler/airbrake, that way if you were slightly out or have wind shear you could retract spoiler and extend the glide and vice verse put more out if you were heading  Grin for a what would be a go around in a powered aircraft with no spoiler and you weren't going for the 'cross controls' type of approach.

If your low and have to use lots of throttle then a failure there is bad, at least if your high and no problem you have the go around option.

What the guys are saying about 180 power off is energy management, have a go starting with straight in landings on idle.
 

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