Originally Posted by
Tchiowa
Is UA going to exact some kind of revenge on you? Probably not. But you are going to inconvenience a lot of people. Check in and not board? They will hold the flight while they figure out what is going on.
Don't do it. See them off before TSA.
For a person who checks-in and no-shows? No. Happens all the time, standby will get the seat, or the plane will just leave with the empty seat.
For a person who checks-in, boards, and then gets off the plane without telling anyone? OK, now we're talking. (Yes, this happened to me on a UA flight recently.)