(CNN) - The FAA will close 173 air traffic control towers at small and medium size airports on April 7 because of forced budget cuts.
Federal officials told tower operators Tuesday that 16 other towers will be closed on September 30.
The airports can stay open even when the towers close because many planes can land without the help of air traffic controllers.
Forced spending cuts, known as the sequestration, are also expected to impact FAA staff.
CNN