When is airspace classified as Class D at an airport with a part-time control tower?

Airspace is classified as Class D at an airport with a part-time control tower when the associated control tower is in operation. In Class D airspace, the operational status of the control tower is the determining factor for the classification of that airspace. When the control tower is open, the airspace is considered Class D, regardless of the time of day or traffic volume.

In this scenario, the presence of a part-time control tower means that the classification can change based on whether the tower is operational at that time. This system allows for controlled traffic management during hours of operation, while at other times, the airspace can revert to uncontrolled airspace, often classified as Class E or G depending on the specifics of the airport and local regulations.

Understanding the operational hours of the tower is crucial for pilots, as it affects their communication requirements and airspace rules during those times. This is why recognizing the operational status of the control tower is key to determining the applicable airspace classification.