[DFLG] Do planes have to speed up to land?

[OWC Jamie]

engine speed is not necessarily an indication of air speed

[pdq]

Buzz wrote:
Generally speaking, the throttle is goosed just prior to the wheels touching down to help smooth out the touch down.

This matches my experience (as a passenger) and makes sense. Prior to touchdown, the airplane is losing altitude. Ideally, at the instant you touch down, if your vertical velocity (and/or acceleration) is near zero, it seems like it will be smoother.

[Black]

Much of the above does not jibe with the studying I did.
The reason for the "goose" just before landing is to bring the nose up so the main wheels touch down first.
I am not comparing the speed of a plane going by my window to the speed just before touching down- I'm comparing it to the speed at similar altitude but on final approach.

[Carnos Jax]

For the vast majority of airplanes, the nose should already be up during the entire final approach. The way most airplanes arrest their vertical descent just prior to touch down is by pulling up on the nose further (which increases the angle of the wing with respect to the airflow, thereby increasing lift). This technique is called a flare. Goosing the throttles increases thrust, which increases speed, which increases lift, which thereby slows the vertical descent also. But this is only done if the pilot feels they're going too slow to begin with (and therefore feels any further attempts to pull up on the nose will risk a stall or tail strike, or that pulling up on the nose will increase drag and make the airplane dangerously slow).

Black wrote: I am not comparing the speed of a plane going by my window to the speed just before touching down- I'm comparing it to the speed at similar altitude but on final approach.

I'm glad you clarified this. But I would still guess that the plane is slower at the beginning of final approach than where you are seeing it. During the portion of a flight where the plane is descending from cruising altitude to landing, it is generally slowing down. As it gets closer to the airport and continues to slow down, there will come a point that the wing can not generate enough lift, and so an airplane must start extending its flaps. Generally speaking , as it gets closer to landing, the airplane slows down more and more, and so the flaps are extended further and further. However, there can be exceptions, depending on traffic loads and patterns for any particular airport, on any given day. This may necessitate that the plane speedup or slow down uncharacteristically during certain portions of the terminal phase of flight, as dictated by air traffic control.

[Black]

Carnos Jax wrote:
For the vast majority of airplanes, the nose should already be up during the entire final approach. The way most airplanes arrest their vertical descent just prior to touch down is by pulling up on the nose further (which increases the angle of the wing with respect to the airflow, thereby increasing lift). This technique is called a flare. Goosing the throttles increases thrust, which increases speed, which increases lift, which thereby slows the vertical descent also. But this is only done if the pilot feels they're going too slow to begin with (and therefore feels any further attempts to pull up on the nose will risk a stall or tail strike, or that pulling up on the nose will increase drag and make the airplane dangerously slow).


[quote=Black]I am not comparing the speed of a plane going by my window to the speed just before touching down- I'm comparing it to the speed at similar altitude but on final approach.

I'm glad you clarified this. But I would still guess that the plane is slower at the beginning of final approach than where you are seeing it. During the portion of a flight where the plane is descending from cruising altitude to landing, it is generally slowing down. As it gets closer to the airport and continues to slow down, there will come a point that the wing can not generate enough lift, and so an airplane must start extending its flaps. Generally speaking , as it gets closer to landing, the airplane slows down more and more, and so the flaps are extended further and further. However, there can be exceptions, depending on traffic loads and patterns for any particular airport, on any given day. This may necessitate that the plane speedup or slow down uncharacteristically during certain portions of the terminal phase of flight, as dictated by air traffic control. OK, I can buy that, thanks.

[nwyaker]

Raise your hand if you're a pilot please.

[flareslow]

Retired pilot

[NewtonMP2100]

......pilot inspektor here....

[flareslow]

And the answer to the initial question is normally, no.

[testcase]

NO, on final approach an aircraft's speed ideally is constant (usually at about 1.3 x its' stall speed). At the proper time, the pilot "flares" the aircraft (pulls the nose up) which reduces the aircraft's speed to the point where the aircraft stalls and falls out of the sky. When done properly, said "fall out of the sky" is done at (or very close) to the ground. The pilot will keep the nose up as long as there is enough speed (energy) to do so. When said energy dissipates, the nose wheel lands. The aircraft now "drives" (taxis) off the runway (with the pilot always in full control).