What speed are commercial planes going when they appear to be hanging in the air?

Question

When I've looked at commercial jetliners that are approaching an airport, they often appear to be just hanging in the air, going only a few miles an hour, if any. How slowly are they actually going? What is the slowest a commercial jetliner can go, and stay aloft?

Answer 1

the two answers above are right. but i think a small clarification is in order. an aircraft really don't "know" how fast it is going compared to the ground (where you as the observer are). all it cares about is the airspeed (the speed of air flowing over the wings). therefore, if there is a strong headwind or a gust (these can go up to 50km/h) the air speed will remain the same (because the plane flies against the air) but it will look quite slow on the ground.

also, there's a bit of an optical illusion involved, especially if you're watching it from a car travelling in the same direction as the plane.

Answer 2

All the above are correct but there's one more illusion factor. The aircraft, especially a 747 are quite large and normally at quite distant. From your observation point it appears closer because of it's size appears to be traveling slow.

It's like driving on a freeway. Poles and mile markers zip past you while objects at a distance pass much slower.

We use to day the C-141 took off like an elevator. It had a good climb rate and tat a distance the vertical reference from the horizon was easier to distinguish than the horizontal movement.

Answer 3

The 737-400 stalls (stops generating lift) at around 100 miles per hour depending on airfield elevation, weight, air density etc.

The larger planes, have a little higher stall speed.

It is safe to assume that these planes are approaching the field at 150 miles per hour or more.

Answer 4

about 180mph or there abouts. depends on size etc. !80 for a 747