The Aircraft Dispatcher shares responsibility for the flight with the Captain, and both are required to sign the Dispatch Release before the flight can legally operate. The dispatcher is responsible for planning the flight, taking into consideration the weather, any maintenance problems on the aircraft, navigational facilities at the appropriate airports, Notices to Airmen (NOTAMS), alternate airports and to exercise flight following while the flight is in progress. The dispatcher maintains communication with his or her flights and is responsible for notifying the Captain of any significant changes that would affect the safety of the flight. It is the responsibility of the dispatcher to delay or cancel a flight when necessary and to make any other operational decisions necessary to ensure the safety of the flight.