The flight is considered "departed" from a time-tracking perspective when the boarding doors are closed. If your flight is scheduled at 2pm and they close the d

The flight is considered "departed" from a time-tracking perspective when the boarding doors are closed. If your flight is scheduled at 2pm and they close the doors at 2pm, even if it takes you until 8pm to get in the air, your flight "left on time". This is a perfect example of "be careful what you measure". Customers don't care when they leave, they care when they arrive, but, since the FAA measures[1] on-time departures, that is what has been optimized for, to the detriment of customers. 1. I would be willing to bet the FAA measures this at the request of the airlines. Measuring arrival time has many variables they can't control, whereas departure, as defined, is mostly controlled by the airlines.