Originally Posted by
golfmad
The OP is on the AA flight to LHR not the BA flight. AA flights to LHR are more likely to depart from the D gates whereas the BA flights are more likely to depart from the E gates.
Exactly, the AA service to LHR from MIA usually departs somewhere close to the AC/FL near D30. I haven't seen that flight departing from low D or high D gates either. It generally departs from mid D gates.