What happens to Class D airspace when the control tower ceases operation for the day?

When the control tower at an airport classified as Class D airspace ceases operation, the airspace classification changes to Class G uncontrolled airspace. Class D airspace is designated for areas around airports with an operating control tower, which provides air traffic control services and instructions to pilots operating in that airspace. When the tower is not operational, those services are no longer available, leading to a transition to Class G airspace.

In Class G airspace, there are fewer restrictions and regulations, giving pilots more freedom to operate without the oversight of air traffic control. This transition also affects the communication requirements between pilots and other aircraft since there is no longer a control tower to provide separation and instructions.

The other options do not accurately reflect the changes that occur when the control tower is not operating. Class D airspace cannot remain classified as such in the absence of the control tower, and it certainly does not become Class A airspace, which is a higher altitude controlled airspace requiring specific IFR flight rules and clearances. The suggestion that it could be temporarily closed is also misleading, as the airspace remains open for use by pilots operating under visual flight rules (VFR) in an uncontrolled environment.