Exactly What is Class D Airspace?

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Photo: Sarina Houston

Class D airspace is the space that surrounds airports that have an operating air traffic control tower, but don't have radar services (or at least the airport is not required to have radar). The airspace surrounding a Class D airport is only classified as a Class D airport when the air traffic control tower is in operation. When not in operation, the airport reverts to a Class E airport, or a combination of a Class E and Class G airport.

The control tower at a Class D airport provides traffic separation for VFR and IFR traffic and can provide VFR traffic advisories, workload permitting.

How to Define Class D Airspace

The following four factors are considered when defining Class D airspace.

Dimensions: Class D airports can be tailored to fit instrument approach procedures that are available at the airport, which means that one Class D airport might look slightly different from another. Literally, the dimensions depend upon instrument approach procedures into a particular airport. It's worth noting that there are extensions for arrivals and departures factored into the airspace dimensions. Normally, the airspace surrounding a Class D airport extends from the surface up to a designated MSL altitude - usually about 2,500 feet AGL.​

Entry Requirements: To enter Class D airspace, a pilot must contact the control tower and establish two-way radio communication prior to entering the airspace.

 

VFR Visibility and Cloud Clearance Requirements: Pilots flying into Class D airspace must maintain at least three statute miles visibility. In addition, pilots must remain at least 500 feet below clouds, 1,000 feet above clouds and 2,000 feet horizontal distance away from clouds while in Class D airspace.

Chart Depiction: Class D airspace is depicted as a dashed blue line on a VFR sectional chart. You may notice that the airspace extends into the arrival and departure paths for IFR traffic.