Overview of Class D Airspace Regulations

Class D airspace. As stated in the AIM Chapter 3-2-5, generally, Class D airspace extends upward from the surface up to 2,500 feet above the airport elevation, surrounding those airports that have an operational control tower. The configuration of each Class D airspace is individually tailored, and when instrument procedures are published, the airspace will normally be designed to contain these procedures. The important thing to remember with Class D, just as any airspace, is that the shape of each one can be unique and are designed to suit the needs of the particular airport and airspace surrounding it. With that being said, Class D airspace has its own typical default design that is frequently found. The height of the airspace is usually 2500 feet AGL or above ground level. The radius will vary depending on the airport but will often be 5 statute miles, which equals around 4.4 nautical miles when rounding up. Why 5 statute miles? The generic 5 miles is in place to contain the airspace in which the Terminal Area Forecast, or TAF, is valid for. Here is an example of a typical Class D airspace surrounding Purdue University Airport. Class D airports are defined on a sectional chart by a blue segmented line. Here you can see the top of the Class D is designated by two digits and hundreds of feet indicating the ceiling is 3100 feet in MSL altitude. The airport elevation is shown here at 606 feet. 3100 minus 600 gives us the 2500 feet AGL height of the Class D. Remember, sectional chart altitudes are always in MSL or above sea level, but that's a different lesson. Another example of Class D is White Plains, New York. It has the normal height of 2500 feet AGL, which we can see from the 3000 feet MSL ceiling and an airport elevation of 439 feet. 3000 minus 500, which we got from the 439 rounded up, gives us 2500 feet AGL. As we defined from the AIM, Class D airspace may be tailored to contain the airspace when an instrument approach exists at the field. The horizontal boundaries extend beyond the normal circular configuration to the northwest and the southeast of the airport, shown here. Just by looking at the runways depicted on the sectional chart, you can see the primary runway is northwest to southeast. So we can conclude that the extensions are to encompass the instrument approaches at West Chester's primary runway. Now that we understand the basic size, shape, and layout of Class D, Let's see what needs to be done before we can enter. Before entering or operating within a Class D airspace, there are a few pilot, aircraft, and communication requirements. Since Class D airspace is smaller than other controlled airspace surrounding airports with an operating control tower, the requirements are also smaller. Unlike some airspace, to enter Class D, no specific pilot certification is required. Any pilot, including a new student pilot, may operate within Class D. In regards to equipment, unless otherwise authorized by ATC, the aircraft must have an operable two-way radio. That's it. Many people get confused and believe since there is a control tower that a Mode C transponder is also required. Although it is always helpful, an altitude reporting transponder is not needed. And the reason is that not... Not all Class D airports have the luxury of having radar services. Some do have their own radar services. Many receive a feed from an overlying terminal or center radar control area, but some have nothing more than the controller's own eyes and a pair of binoculars. Since a working radio is the only required equipment, it is no surprise that in order to enter, depart, or operate within Class D airspace, two-way radio communication must be established with air traffic control. When approaching a Class D airport or airspace, the pilot should contact the control tower on the published frequency with their position, altitude, destination, and any requests. Here is an example. Lafayette Tower, November 1, 210 miles south, 5500, inbound for landing. Now how do you know that two-way radio communication has been established? The determining factor is when the aircraft's call sign or tail number is read back to the pilot. An example of this would be, Once ATC responds with your tail number, in this case, November 1234, then two-way radio communication has been established. So what if ATC responds with, November 1, it's our standby. Are you allowed to enter? At this point, although no specific instructions were given by the controller, two-way radio communication was established since the tail number was read back, and the pilot is permitted to enter the Class D airspace. However, even if two-way radio communication was established, But ATC instructs you to remain clear of the airspace, then obviously the pilot should stay outside of the Delta until told to do so. On a side note, this required readback of your tail number means that it is important on your initial call that you use your full tail number and not an abbreviated version. Now that we are within the Class D airspace, we have a few other requirements to take into consideration. Unless we are operating under IFR and on an instrument flight plan, we have some weather requirements to keep in mind. Within a Class D airspace, basic VFR requirements are in place. In order for the airport to be considered VFR, there must be at least 3 statute miles visibility and a 1,000 foot ceiling. While operating VFR with this 3 mile visibility or greater, we must also remain 500 feet below 1,000 feet above, and 2,000 feet horizontally from any cloud. We also have a speed restriction while operating close to a Class D airport. The FARs, particularly Part 91.117, states that, unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots. So in other words, we are not permitted to fly faster than 200 knots indicated within Class D, or more specifically within 4 nautical miles under 2,500 feet AGL of that airport. But since we learned that most Class D airspace has a 4.4 nautical mile radius with a ceiling of 2,500 feet AGL, this restriction also falls into the vertical and horizontal dimensions of most Class Ds. In summary, Class Delta airspace is typically 2,500 feet AGL with a 5 statute mile radius. To operate within a Class D, all we need is an operable two-way radio with established two-way radio communication. While operating, we must maintain VFR with 3 statute miles visibility and 500 feet below, 1000 feet above, and 2000 feet horizontally from clouds. We must also maintain a speed restriction of 200 knots or less. Since the size and shape of each Class D is individually tailored, It is important to check all resources including the current airport facility directory and aeronautical charts to determine the dimensions of the airspace at each airport you plan to fly in or out of. Also, not all control towers operate around the clock, so check the current AFD to know when the tower is operating. When the tower is closed, the class delta will revert to either class golf or class echo and that information can also be found in the airport facility directory. When the airspace becomes either Class G or E, then the corresponding equipment, operating and weather requirements for the new airspace take effect.

The important thing to remember with Class D, just as any airspace, is that the shape of each one can be unique and are designed to suit the needs of the particular airport and airspace surrounding it. With that being said, Class D airspace has its own typical default design that is frequently found. The height of the airspace is usually 2500 feet AGL or above ground level.

The radius will vary depending on the airport but will often be 5 statute miles, which equals around 4.4 nautical miles when rounding up. Why 5 statute miles? The generic 5 miles is in place to contain the airspace in which the Terminal Area Forecast, or TAF, is valid for. Here is an example of a typical Class D airspace surrounding Purdue University Airport. Class D airports are defined on a sectional chart by a blue segmented line.

Here you can see the top of the Class D is designated by two digits and hundreds of feet indicating the ceiling is 3100 feet in MSL altitude. The airport elevation is shown here at 606 feet. 3100 minus 600 gives us the 2500 feet AGL height of the Class D. Remember, sectional chart altitudes are always in MSL or above sea level, but that's a different lesson.

Another example of Class D is White Plains, New York. It has the normal height of 2500 feet AGL, which we can see from the 3000 feet MSL ceiling and an airport elevation of 439 feet. 3000 minus 500, which we got from the 439 rounded up, gives us 2500 feet AGL.

As we defined from the AIM, Class D airspace may be tailored to contain the airspace when an instrument approach exists at the field. The horizontal boundaries extend beyond the normal circular configuration to the northwest and the southeast of the airport, shown here. Just by looking at the runways depicted on the sectional chart, you can see the primary runway is northwest to southeast.

So we can conclude that the extensions are to encompass the instrument approaches at West Chester's primary runway. Now that we understand the basic size, shape, and layout of Class D, Let's see what needs to be done before we can enter. Before entering or operating within a Class D airspace, there are a few pilot, aircraft, and communication requirements. Since Class D airspace is smaller than other controlled airspace surrounding airports with an operating control tower, the requirements are also smaller.

Unlike some airspace, to enter Class D, no specific pilot certification is required. Any pilot, including a new student pilot, may operate within Class D. In regards to equipment, unless otherwise authorized by ATC, the aircraft must have an operable two-way radio. That's it. Many people get confused and believe since there is a control tower that a Mode C transponder is also required. Although it is always helpful, an altitude reporting transponder is not needed.

And the reason is that not... Not all Class D airports have the luxury of having radar services. Some do have their own radar services.

Many receive a feed from an overlying terminal or center radar control area, but some have nothing more than the controller's own eyes and a pair of binoculars. Since a working radio is the only required equipment, it is no surprise that in order to enter, depart, or operate within Class D airspace, two-way radio communication must be established with air traffic control. When approaching a Class D airport or airspace, the pilot should contact the control tower on the published frequency with their position, altitude, destination, and any requests.

Here is an example. Lafayette Tower, November 1, 210 miles south, 5500, inbound for landing. Now how do you know that two-way radio communication has been established? The determining factor is when the aircraft's call sign or tail number is read back to the pilot.

An example of this would be, Once ATC responds with your tail number, in this case, November 1234, then two-way radio communication has been established. So what if ATC responds with, November 1, it's our standby. Are you allowed to enter?

At this point, although no specific instructions were given by the controller, two-way radio communication was established since the tail number was read back, and the pilot is permitted to enter the Class D airspace. However, even if two-way radio communication was established, But ATC instructs you to remain clear of the airspace, then obviously the pilot should stay outside of the Delta until told to do so. On a side note, this required readback of your tail number means that it is important on your initial call that you use your full tail number and not an abbreviated version. Now that we are within the Class D airspace, we have a few other requirements to take into consideration.

Unless we are operating under IFR and on an instrument flight plan, we have some weather requirements to keep in mind. Within a Class D airspace, basic VFR requirements are in place. In order for the airport to be considered VFR, there must be at least 3 statute miles visibility and a 1,000 foot ceiling.

While operating VFR with this 3 mile visibility or greater, we must also remain 500 feet below 1,000 feet above, and 2,000 feet horizontally from any cloud. We also have a speed restriction while operating close to a Class D airport. The FARs, particularly Part 91.117, states that, unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots.

So in other words, we are not permitted to fly faster than 200 knots indicated within Class D, or more specifically within 4 nautical miles under 2,500 feet AGL of that airport. But since we learned that most Class D airspace has a 4.4 nautical mile radius with a ceiling of 2,500 feet AGL, this restriction also falls into the vertical and horizontal dimensions of most Class Ds. In summary, Class Delta airspace is typically 2,500 feet AGL with a 5 statute mile radius. To operate within a Class D, all we need is an operable two-way radio with established two-way radio communication. While operating, we must maintain VFR with 3 statute miles visibility and 500 feet below, 1000 feet above, and 2000 feet horizontally from clouds.

We must also maintain a speed restriction of 200 knots or less. Since the size and shape of each Class D is individually tailored, It is important to check all resources including the current airport facility directory and aeronautical charts to determine the dimensions of the airspace at each airport you plan to fly in or out of. Also, not all control towers operate around the clock, so check the current AFD to know when the tower is operating.

When the tower is closed, the class delta will revert to either class golf or class echo and that information can also be found in the airport facility directory. When the airspace becomes either Class G or E, then the corresponding equipment, operating and weather requirements for the new airspace take effect.

Transcript for:Overview of Class D Airspace Regulations

Transcript for:
Overview of Class D Airspace Regulations