Gen. Esperanza: Freedom.
[John McClane appears and punches him in the face.]
John McClane: Not yet.
In circling over Washington Dulles, a plane would fly over several airports that they could land at with perfect communication, including Richmond, Baltimore, Andrews AFB, etc. Also, there is no communication from the airport to the plane but the plane would be in range of no fewer than 15 transmitting stations that could have relayed messages.
The film is based on a book called "58 Minutes" by Walter Wager. In the book, it is the hero's young daughter, not his wife, that is on one of the planes.