I had a similar encounter over the Adirondacks transitting Vermont. My VSI
started indicating a 100-200 ft/min descent and I subsequently pulled up.
Soon I found myself with full power, 80 kts indicated and a sorry-looking
groundspeed. ATC asked about my indicated airspeed and I asked for lower.
Once cleared, (you guessed it) I hit the other side of the wave and my
airspeed went into the yellow arc while maintaining level flight--forcing me
to reduce power. All this in a Warrior at about 6000 feet MSL.

Asked a couple of people about this and the ones who experienced it all
agreed it was freaky at first and all of our initial reactions were to scan
the panel for a problem.

Marco

"Michael 182" wrote in message
news:Bwq0d.166098$Fg5.68105@attbi_s53...
Hit a mountain wave today near Pikes Peak at FL190 in my TR-182. First I
couldn't maintain FL190 (I only have 300-400 fpm climb at that altitude
anyway) as my indicated airspeed descended to 80 K. Called ATC, got a
block altitude, FL 180 - 200. About a minute later I needed the upside.
Shot to over 2000 fpm climb (VSI was pegged) and with the nose pointed
way down leveled off at FL 195 and ground speed of 190 knots. Fun stuff.

Michael