My ASES instructor had a habit of tapping on the altimeter from time to
time. He said you had to do that in the old days to get an accurate
reading.

"Wyatt Emmerich" wrote in message
...
I had a my two-year transponder/static system check while visiting my
mother
in San Antonio. When I departed, I noticed the airspeed didn't come up
like
it should. I attributed this to shifting winds and assumed I had a slight
tailwind. Then in cruise, I did my normal operating performance check. My
IAS was about 30 knots low, but my groundspeed was normal. I tapped on the
airspeed indicator and it gained six knots. Question #1: How would a
transponder/static check screw up my airspeed? Was this just coincidence?
Question #2: How do you check accuracy of an airspeed indicator? Question
#3: How long should you go before replacing an airspeed indicator?