Yesterday we were flying PWM-JFK-TPA on DL award tickets. The PWM-JFK flight was delayed and we didn't arrive at JFK until 1:25 p.m. As it turns out, there were other people on the flight connecting to the 1:35 p.m. flight to TPA--a total of 9 of us on the DH8! We landed and ran into the terminal at gate 23 and saw that the TPA flight was departing from gate 21, giving us a chance to make our connection. When we arrived at the gate, we saw the door was closed. I looked at my cellphone and it was 1:30 p.m. I told the GA that we and 7 other people coming from PWM were on the flight. Her response was "Flight's closed." I pointed out that it was still 5 minutes to departure time, and she said "When the tower tells us to shut the door, we have to shut the door."

By the scheduled departure time, all 9 of the pax headed to TPA were at the gate. I understand that flights often close before departure time when all confirmed pax are boarded, or if it is clear that missing pax will misconnect. I asked the other GA if he had noticed that 9 of the missing pax were on another DL flight that was on the ground (and only 2 gates away). He used the same line: "When the tower tells us to shut the door, we have to shut the door." The whole time we're having this discussion, the plane was sitting at the gate. The plane did not push back until 10 minutes after all of us arrived at the gate.

All of us had to wait until 8:26 p.m. to take the next DL flight to TPA (that was delayed from 7:55 p.m.), arriving in TPA around midnight, about 7 hours late. The GA said that there were no other DL connecting flights that would get us there sooner that he could confirm us on, and refused to look for connections on other airlines.

I have seen GAs come aboard a plane in the final stages of boarding and close the flight when, in their judgment, it is ready to go. I have also heard the announcement that "We cannot shut the door until all passengers are seated." I also understand that at some airports (like JFK), missing a pushback time by a few minutes minute can delay wheels up time by 15 minutes or more. However, I didn't realize that the tower dictated when a plane shuts its door. The door can't close while people are still boarding or if (according to FA warnings) everyone is not seated. Wouldn't the tower have to know that the door could be closed before giving the order to close it?

Has anyone else ever been told that "When the tower tells us to shut the door, we have to shut the door"?