Ski instructors cant, but they will call into mountain safety and give them a description of you. Happened to me at Keystone earlier this year. A lifty saw me jump over a sign at the bottom of the Montezuma Lift. When i got to the top, i started to ski down and was stopped by a yellow jacket half way down the run. He said he had been informed of what i had done. I denied that is was me and since he didnt personally see me do it, he had no basis to pull my pass because i claimed he had the wrong guy. Dude was a total dick and on a huge power trip.