Plain English Meaning

The rules for the airspace around some airports change depending on whether the tower is open. The same piece of sky might be one type of airspace during the day and a different type at night.

Full Definition

Airspace at certain airports that changes classification depending on the time of day or whether the control tower is operating. For example, the airspace surrounding a tower-controlled airport may be Class D when the tower is open, but revert to Class E or Class G when the tower closes. The effective times and resulting classifications are published on aeronautical charts and in the Chart Supplement.

Context Anchor

Seen in airport information pages, chart notes, and preflight planning when checking what airspace rules apply at the time of the flight.