Class D Airspace Overview

Definition and Configuration

• Class D Airspace: Extends from the surface up to 2,500 feet above the airport elevation.
• Surrounds airports with an operational control tower.
• Configuration: Individually tailored to suit the needs of the particular airport and surrounding airspace.

Default Design

• Height: Generally 2500 feet AGL (Above Ground Level).
• Radius: Typically around 5 statute miles (~4.4 nautical miles).
• Designed to contain airspace for the Terminal Area Forecast (TAF).

Examples

• Purdue University Airport: Class D depicted with blue segmented line. Altitude shown in MSL (Mean Sea Level).
• White Plains, NY: Normal height and extensions for instrument approaches.

Entering Class D Airspace

Requirements

• No specific pilot certification required.
• Aircraft must have an operable two-way radio.
• No Mode C transponder required.

Communication

• Establish two-way radio communication with ATC.
• Contact control tower with position, altitude, destination, and requests.
• Radio communication confirmed when ATC reads back the aircraft's tail number.
• Must follow ATC instructions, including staying clear if instructed.

Operating Within Class D Airspace

Weather Requirements

• Basic VFR: Minimum 3 statute miles visibility, 1,000-foot ceiling.
• Must stay 500 feet below, 1,000 feet above, and 2,000 feet horizontally from clouds.

Speed Restrictions

• No more than 200 knots indicated airspeed at or below 2,500 feet AGL within 4 nautical miles of the airport.

Important Considerations

• Resource Check: Determine airspace dimensions using airport facility directory and aeronautical charts.
• Tower Operations: Check if the control tower operates around the clock.
• Tower Closure: Class D airspace may revert to Class G or E when the tower is closed, altering requirements.

Summary

• Class D airspace typically extends 2,500 feet AGL with a 5 statute mile radius.
• Key requirements: operable two-way radio, established communication, VFR conditions, and speed limit.
• Tailored size and shape require checking current charts and directories for each airport.
• Be aware of changes during non-operational tower hours.