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Cessna 172 landings with full flaps. I have been taught to land with and without power. Give me feedback please. Which way should I continue my training?

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    $\begingroup$ Without. It's so light that even a little power will use more runway than you'll really need. $\endgroup$ – acpilot Jul 4 '17 at 21:17
  • $\begingroup$ @acpilot I have never flown that plane, and I'm not sure, but with very light planes, the problem of using full flaps is that the high drag may slow the plane too much in a very short time (due to the low mass of the plane) and if the pilot is landing without power and gets distracted for a fraction of a second, he may find himself below the stall speed... $\endgroup$ – xxavier Jul 4 '17 at 21:39
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    $\begingroup$ @xxavier, flying a 172 is nowhere near that intesne. If a pilot finds himself in the position you describe, he's doing it wrong and needs remedial training. $\endgroup$ – acpilot Jul 5 '17 at 0:02
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This is really a question for your instructor: if you've been taught both methods then he should be able to explain when to use a little power and when not to.

Having said that, it all depends: there are good reasons to land with and without power, depending on the situation.

A normal landing with full flaps in a 172 is typically done without power. The Cessna 172S POH I have doesn't even mention power in the normal landing procedures; it gives a target airspeed instead.

A short-field landing is also usually without power, to minimize the runway distance needed. The same POH says:

Power -- REDUCE to idle after clearing obstacle

For a soft-field landing on the other hand, it's normal to carry a little power in order to touch down as gently as possible and avoid sinking into the runway surface. The FAA's Airplane Flying Handbook says in Chapter 8:

Power is used throughout the [soft-field] level-off and touchdown to ensure touchdown at the slowest possible airspeed,

Finally, you might also use a little power if you bounce on landing, to stabilize the aircraft and re-flare (runway length permitting). But that's a bit more challenging and most low-time pilots should just apply full power and go around instead.

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As a 172 pilot I cannot think of any normal cases where landing with power would be a good idea as any power will extend the landing distance significantly and extend the float and hold-off. In a normal landing I might add burst of power if the sink rate gets too high, but I would always cut it off as soon as I reach ground effect.

Throttle is used in short/soft field landings which are at the edge of the performance envelope. These are done at low speed and high drag, the throttle is needed to keep the airplane above stall speed and force air over the tail's control surfaces so you maintain control. You keep the throttle on in the flare until you reach your touchdown point and then you gently close it, and the airplane stalls onto the strip.

So as you continue your training you should practice both techniques as each has its own purpose, and you should keep practicing both after you get your licence. Just keep in mind that the short/soft field technique has much less room for error, so make sure you know what you're doing!

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  • $\begingroup$ I can think of a situation where I'd carry some power (and more speed) on final: a field with a steep dropoff on the approach end, where a good headwind might produce a downdraft. $\endgroup$ – jamesqf Jul 9 '17 at 18:25
  • $\begingroup$ I'm not saying not to have power on final, I'm talking about power on the roundout and flare @jamesqf. Extra power on roundout doing downhill in a 172 will give you a lot of float. $\endgroup$ – GdD Jul 10 '17 at 11:34
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It depends. You should not be afraid to use whatever power setting is necessary to maintain a proper glide path. Especially with full flaps, when you get low and slow you might need a lot of power.

The answer about the Soft-Field and Short-Field landings is excellent, and goes to the point that "it depends."

I looked in two POHs.

The POH for a 1981 C172RG doesn't mention whether normal landings should be done "power-on" or "power-off", which to me means it is my option.

For comparison I also looked at the POH for a 1979 C152, which says, "Normal landing approaches can be made with power-on or power-off...." However, it says that "actual touchdown should be made with power-off and on main wheels first."

I was taught to always keep my hand on the throttle during landings and use as necessary.

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Are you referring to a power/unpowered approach, using power during the flare, or using power as the wheels touch the ground?

A few considerations (without giving an actual set-in-stone answer)

On approach:

1) approaches without power (commonly called "dead-stick landings) are OK, but if you end up just a little short, it's a bad time to discover that your engine has stopped during that descent. At minimum, give it a little power periodically to confirm it's still responding.

2) cutting power at altitude and gliding the whole way down introduces a lot of cooling (less heat from combustion and friction within the engine combined with increased airflow). Most (but not all) agree that rapid temperature changes reduce engine life.

3) from a speed perspective, maintaining a cruise descent from several miles out will get you there faster than cutting the engine closer and being limited by Vno, Vne, or RPM (which will still be high on a fixed prop aircraft with the throttle at idle on a steep descent)

during flare and touchdown:

1) with more flaps and less power, your approach angle will be steeper. With power and a lower flap setting, the shallow approach angle will be more forgiving for newer pilots who are still fine tuning their flare and touchdown. I had trouble getting really smooth landings with full flaps and no power, and found that with lower flap settings and a tiny bit of power, I'd hear the wheel bearings spinning before I felt the landing. This can be useful for a student to gain more spatial awareness of the height of the aircraft over the runway, and can be a good stepping stone into greasing perfect landings in any configuration.

2) of course, more flaps and less power lead to a shorter ground roll. So don't have a crappy approach and run out of runway.

3) keep in mind that your landing configuration will change depending on situation, and being able to adjust to the situation is very important. 30+ flaps in gusty crosswinds can create more problems than the solve, and tailwind landings with full flaps can be interesting as well.

Source: c172 owner, commercial / instrument rated, skydive pilot (in c182 and other airframes)

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  • $\begingroup$ Re "discover that your engine has stopped", or discover that pushing in the throttle too quickly causes it to stumble and almost stall. (Been there, done that, had to clean the seat afterwards :-)) $\endgroup$ – jamesqf Jul 9 '17 at 18:28

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