Class D Airspace
Class D airspace is generally pretty quiet but has the capacity and infrastructure to handle large volumes of traffic.
Class D airspace is charted on a VFR Sectional by a blue segmented line.
The lateral dimensions of Class D airspace are individually tailored to facilitate IFR arrives and departures. The airspace begins at the surface and extends to 2,500 ft AGL. The MSL altitude of the ceiling is displayed as a two digit number within a dashed box. Some Class D airports have extensions protruding from the main airspace. These extensions are used for instrument approaches. If an extension is 2 NM or less, it is Class D airspace. If there is more than one extension and anyone of the extensions is greater than 2 NM, then all extensions are designated as Class E airspace.
Prior to entering Class D airspace, radio contact must be established with ATC. If ATC responds with, "(Your aircraft call sign), standby," then contact has been established. If ATC does not use your call sign, contact has not been established.
Class D airspace is only in effect when the tower is operational. When the tower is closed the airspace reverts to Class E and no clearance is required to enter. During these hours CTAF calls are over tower’s frequency.
A transponder is not required to operate within Class D airspace.
VFR traffic must remain 500 ft below, 1000 ft above, and 2000 ft laterally from clouds with 3 miles of visibility while operating within Class D airspace.