flight instrumentsFAA-published sample question (IRH, Aug 2021)
If you need to use an alternate static source during level flight, you can expect to see
A
a higher indication on the altimeter.✓ Correct Answer
B
a momentary descent on the VSI.
C
a lower indicated airspeed.
Explanation
The alternate static source usually vents to the cabin, where pressure is slightly lower than outside, so PHAK Chapter 8 says the altimeter reads higher, the airspeed indicator reads greater, and the VSI shows a momentary climb. A lower airspeed or a momentary descent is the opposite of what occurs.
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