Part 4/8:
Upon receiving confirmation of a bomb threat, air traffic control acknowledges the seriousness of the situation. Controllers across the board begin to reassign aircraft, redirecting them to avoid possible conflict with United 93, which is now perceived as a potential threat. Pilots of surrounding flights, including American Airlines and Delta operators, are alerted to pay close attention to developments concerning United 93.
In the air, other pilots express confusion and concern about the unusual transmissions occurring, trying to piece together the nature of the emergency. Some indicate having heard "screaming" over the radio—a phrase that added weight to the terror taking place aboard United 93.