Airspeed Indication and Relative Wind

Scott Lowrey wrote:

If I'm descending slowly with a relatively nose-high attitude - say, in
preparation for a short field landing - does the high angle of the pitot
tube have any effect on indicated airspeed? (I suppose all designs are
different - say this is a 172.)

If your plane has a POH, there should be an airspeed calibration table or
chart in Section 5 "Performance."

My Warrior II's ASI will underread by about 7 kt at a high angle of attack,
and overread by about 7 kt at a very low angle of attack. The ASI in a
Cessna 172P will underread by 6 kt at a low angle of attack (7 kt with full
flaps), or overread by 6 kt at a high angle of attack.

In theory, I think, the ASI could be recalibrated to be more accurate at
high and low settings, but why would the manufacturers bother? The
calibration errors make the plane look like it has a much slower stall speed
and a slightly higher cruise speed than it really does.


All the best,


David