Flaps 10 during inital emergency descent?

[midlifeflyer]

Precisely. That was my point. Don't reinvent the wheel. If Cessna had wanted the emergency procedure to point to extending flap, Cessna would have put it in the procedure. They did not.

That's silly. The landing without engine power checklist says to use flaps as required, together with a recommendation for 30°.

It just doesn't say when, and the PIM doesnt have a "Somewhere In Between Loss of Power and Landing With No Power" checklist.

So I'm guessing it's sometime between the loss of power and before the touchdown. Doing it in a way that it maintains the stability of the approach and landing is better than dumping in all 30° 10' above the ground. OTOH, adding the drag of flaps while you are still optimizing your glide is not the place to do it, but I don't think the OP or anyone else was suggesting it was.

CA1900's advice is still pretty solid.

 

[TheInsider]

When performing a simulated glide approach Abeam the numbers for engine failure simulation go to best glide then flap 10 or leave them down?

Whatever config. you would normally have at that point with the engine running (not simulated anything).

 

[Amish RakeFight]

Flaps have been well addressed already. Use as needed. Too many variables (such as distance from desired landing point, winds, etc.) to teach a spring-loaded method such as 10 degrees all the time. Flaps increase drag. The manipulation of flaps should take place once you've determined that you can make your target. This should take place fairly close or directly over your landing area. To use 10 degrees while gliding towards a suitable field or runway will do nothing to aid your glide.

I'll add a couple of things not yet mentioned. This may not apply to the 172, but when you begin performing glides in a constant speed aircraft, you'll want to teach the student to keep the throttle forward and the prop back (high pitch). This will help increase the glide distance.

Also, when using the best glide speed, it may be necessary to increase this speed with a strong headwind. Inversely, you'll need to decrease your best glide speed when faced with a strong tailwind. This will help you extend your glide.

 

[ultrarunner]

Best glide speed is CLEAN in a 172, right? If you put flaps down, it's not best-glide speed anymore, or am I missing something?

 

[avbug]

but when you begin performing glides in a constant speed aircraft, you'll want to teach the student to keep the throttle forward and the prop back (high pitch).

That depends on the aircraft and the propeller system in use. It's not true, in many cases, because retarding the prop control will have no effect. Again, visit the procedures for your specific aircraft.

If you put flaps down, it's not best-glide speed anymore, or am I missing something?

Nope. You're not missing anything.

Whatever config. you would normally have at that point with the engine running (not simulated anything).

Not necessarily true. Again, it depends what you're attempting to do with the aircraft. If your engine has just failed, the landscape has changed, somewhat.

So I'm guessing it's sometime between the loss of power and before the touchdown. Doing it in a way that it maintains the stability of the approach and landing is better than dumping in all 30° 10' above the ground. OTOH, adding the drag of flaps while you are still optimizing your glide is not the place to do it, but I don't think the OP or anyone else was suggesting it was.

Just prior to impact may be precisely the place to add flaps, and may be quite appropriate to the situation.

That's silly. The landing without engine power checklist says to use flaps as required, together with a recommendation for 30°.

It just doesn't say when, and the PIM doesnt have a "Somewhere In Between Loss of Power and Landing With No Power" checklist.

No, it's not silly, and that's why I specifically pointed to technique, as opposed to procedure. There's a difference.

 

[pilotyip]

Nope

Best glide speed is CLEAN in a 172, right? If you put flaps down, it's not best-glide speed anymore, or am I missing something?

When you put down any flaps, you are no longer concerned about best glide. You are concerned about shedding potential energy (represented by airplane speed and altitude) by converting it into kinetic energy (represented by airplane increased drag and altitude loss). This is all done so that you arrive over your point of intended landing with close to zero energy available.

 

[labbats]

The most important thing in teaching simulated engine outs is the element of surprise (I usually did it during a cross country when they were doing some kind of high-task requirement) and instilling in them that there will be a totally different glide if the engine does indeed stop. The prop spinning at idle will descend completely different than if it stops altogether and becomes a big speed brake.

Make your student shocked that the engine failed and force them to find a best choice for a forced landing. Make them take it as low as you feel comfortable and make them see the land come up at them and the flaws in any divert point up close. You may save their life someday.

 

[bestfwdspd]

Flaps, best glide and glide streaching

To clarify: Best glide speed results in the greatest distance traveled for the altitude lost in a no wind condition. So a C172 with say a 70KIAS best glide speed, gliding into a 70 knot headwind without any speed additive would decend vertically. To penatrate the wind you would typically estimate the wind being penetrated(usually 5-20 knots)and add half that amount to best glide speed to have a target "speed to fly". Flaps, since they steepen the decent, would be added as the need to steepen the profile presents. Conversely if there is a need to get to the landing site, play off the energy in a clean configuration and once in ground effect add the flaps in increments from 0 to full. In the C-172 the flaps will generally add perhaps 1000 feet of horizontal travel prior to touchdown and could jump a fence, stream, rock or a cow, etc.

 

[rumorhasit]

The most important thing in teaching simulated engine outs is the element of surprise (I usually did it during a cross country when they were doing some kind of high-task requirement) and instilling in them that there will be a totally different glide if the engine does indeed stop. The prop spinning at idle will descend completely different than if it stops altogether and becomes a big speed brake.

Make your student shocked that the engine failed and force them to find a best choice for a forced landing. Make them take it as low as you feel comfortable and make them see the land come up at them and the flaws in any divert point up close. You may save their life someday.

Good point, I even sim engine failure during slow flight.