Question

How will pitot static instruments be affected by the use of the alternate static source

A) Airspeed and Altimeter will read higher
B) Airspeed and Altimeter will read lower
C) Only Airspeed will be affected
D) Only Altimeter will be affected

Answer 1

Using the alternate static source generally results in both the airspeed indicator and altimeter displaying higher readings, due to the lower static pressure in the alternate source.

Step-by-step explanation:

When using the alternate static source, pitot-static instruments such as the airspeed indicator and altimeter may be affected due to differences in the static pressure being measured. The typical effect of using an alternate static source is that the airspeed indicator will generally show a higher airspeed and the altimeter will indicate a higher altitude compared to using the primary static source.

This is because the alternate static source, which may be located inside the pressurized cabin, often has a slightly lower static pressure at altitude compared to the outside atmosphere. This lower static pressure will cause the instruments to register as if they are in a lower pressure environment, thus showing higher airspeed and altitude readings. Therefore, the correct answer is A) Airspeed and Altimeter will read higher when using the alternate static source.