Originally Posted by Often1

This thread is full of terrible advice. And the conclusions are simply wrong.

The flight was served by a CRJ-200 with 50 passenger seats. DOT IDB rules exempt flights served by aircraft with less than 60 seats. Thus, while OP was likely involuntarily denied boarding, he is due $0 compensation.

OP should nonetheless file a short & sweet complaint with UA noting that he was at the gate with a valid BP at T-21 and that he was denied boarding. Let UA sort it out. UA will explain why the flight is exempt, but will likely toss some miles as a customer service gesture.

The DOT complaint is, of course, a waste, because there was no DOT violation.