B6 1090 is the last DCA BOS of the night with a posted boarding time of 20:29 and a departure time of 20:59. Last night, Mon 8/29, they annoucned a "final boarding call," at about 20:25, which is 4 minutes before the posted boarding time.

From ExpertFlyer:
Comments:
DCA 859P B 30
BOS 1029P
4DCA/OUT 2041 OFF 2102 *2002*HDQFTP
2BOS/ON 2203 IN 2209 *2109*HDQFTP

I notice a lot of the time when they have these early close outs, they don't get a much faster "off time."

I just thought it was really interesting they announced the final boarding call at 20:25.

I guess they would be obligated to wait to close the door until 20:44, with there 15 minute rule, if they had missing pax that were checked in to the flight.

Also BTW the flight was pretty light with only about 48 passengers.

It also got me to thinking lets say they closed the door at 20:35, and there were in fact checked in pax that missed the flight, and again that door close would be earlier than what they publish as the door close time; would such a pax be entitled to involuntary denied boarding compensation? Typically IDB comes up re oversales, but I wonder if it can be invoked with this kind of scenario? I know also AA has been documented to try to close flights really early, and they actually post a 10 minute door close time.