That's glider stuff. You tap it instead of allowing engine vibration to do
it.

If the engine is running, you shouldn't need to touch it.

"William W. Plummer" wrote in message
newsTjfc.38063$_K3.163660@attbi_s53...
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.