1. Federal Airspace Classifications
LCDR Hutchinson
17 February 2006
This is not intended to supersede FARs or AIM, this is merely one pilots attempt to make this stuff easy to remember. Good luck!

2. Airspace Diagram
As depicted in the official publications… Clear as mud?

3. Airspace Overview Types Requirements for Designation.
Alpha, Bravo, Charlie, Delta, Echo, and Golf.
Prohibited, Restricted, MOA, Alert, and Warning areas.
Land based ADIZ, Controlled Firing Area, TRSA, National Security Areas, and Wildlife refuges.
Requirements for Designation.
Requirements for Operating within each.
Chart Depictions
When you think about airspace, think about three things: 1) why is it there? 2) what are the requirements to operate within it, and 3) what does it look like on a chart?

4. Class “D” Airspace
2500 ft AGL
To follow the “crawl, walk, run” mentality, lets start with the most basic airfield airspace.

5. Class “D” Airspace
What is required to designate an airport with Class “D” airspace?
“Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower.” – AIM 3-2-5
What are the normal dimensions?
“The configuration of each Class D airspace area is individually tailored…” - AIM 3-2-5
What airspace is effective when the Tower closes?
Is the airport closed?
What is required to operate in Delta Airspace?
“Two-way radio communication must be established with the ATC facility… prior to entry and thereafter maintain those communications while in Class D airspace.” - AIM 3-2-5
“…if the controller responds to the initial radio call without using the aircraft identification, radio communications have not been established …”
Point 1: Key is “operational control tower.” When the tower is closed, the airfield no longer meets the requirements for establishing a Class D airspace.
Point 2: Used to be 5 nm around a field, then 4.2, now its individually tailored. Pay attention to the chart, don’t let yourself get a flight violation for being careless!
Point 3: Point here is just because the tower is closed, the airport may not be. The airfield may revert to a CTAF frequency after hours, which means you can still land and take off from it.
Point 4: Key is comm’s established, no “clearance” required, per se.

6. Class “D” Depiction

7. Class “D” Bonus Question
What is the significance of the [-20] symbol over Chambers Field????
“A minus ceiling value indicates surface up to but not including that value.”

8. Class “C” Airspace
4000 ft AGL
5 nm
1200 ft AGL

9. Class “C” Airspace
What is required to designate an airport with Class “C” airspace?
“Generally, that airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements.” - AIM 3-2-4
What are the normal dimensions??
“…Each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area… and a 10 NM radius shelf area that extends from 1200 to 4000 feet above the airport elevation…” – AIM 3-2-4
What airspace is effective when the Tower closes?
Is the airport closed?
Point 1: Two requirements: Operational Control Tower AND a servicing Radar approach control. FAR/AIM talk about a “certain amount of IFR traffic, emplanements/deplanements, etc.” What is a “certain amount?” Bottom line is all of that gets you the Radar approach control.
Point 2: Key is 4000 ft AGL, not MSL. Read the chart and ask yourself what that would say if it were over Denver. There is a 20 nm radar service area, but that is voluntary. Becomes a little less voluntary if the Class C airfield is your destination, however, still voluntary.
Point 3: As with Delta, the airspace goes away when the tower closes. However, just because the airspace goes away, the airport may or may not be open for CTAF traffic. For example: PNS tower closes, Delta goes away, but the airfield remains open in a Class E status. Whiting Field tower closes, Charlie goes away, but the airport REMAINS CLOSED. Emergency traffic only.

10. Class “C” Depiction
Note the cut-out and effective Charlie airspace for Ferguson Field NW of NAS Pensacola.

11. Class “C” Requirements
What is required to operate in Class “C” Airspace?
“Two-way radio communication must be established with the ATC facility… prior to entry and thereafter maintain those communications while in Class C airspace.” - AIM 3-2-4
“…if the controller responds to the initial radio call without using the aircraft identification, radio communications have not been established …”
What is required to fly under it?
“G” airspace, no additional voice or transponder requirements.
Point 1: Again, communications established. No clearance required.
Point 2: NO transponder requirements for flying UNDER Charlie airspace, however it is required to fly over the top.

12. Class “C” Bonus Question
What is required to fly over it?
“In general, [aircraft are required] to be equipped with Mode C transponders when operating…within and above all Class C airspace, up to 10,000 feet MSL.” – AIM (F) or FAR (b)(1) and (b)(5)(i)
“Unless otherwise authorized…no person may operate an aircraft unless [it] is equipped with an operable coded radar beacon… in all airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL…” - FAR (b)(5)(i)

13. Class “B” Airspace

14. Class “B” Airspace
What is required to designate an airport with Class “B” airspace?
“Generally, that airspace from the surface to 10,000 feet MSL surrounding the nation’s busiest airports in terms of IFR operations or passenger enplanements.” - AIM 3-2-3
What is the normal size?
“The configuration of each Class B airspace area is individually tailored and consists of a surface area and two or more layers, and is designed to contain all published instrument procedures once an aircraft enters the airspace.” – AIM 3-2-3
Point 1: All others talk about tower/approach requirements. Bravo is merely “established.” It exists because somebody said so.
Point 2: The only given about the shape of Bravo airspace is that it has a surface area and two or more layers. STUDY THE CHART!!!

15. Class “B” Airspace
What are the requirements to enter “B” airspace? (FAR )
Two-way radio communications.
ATC Clearance.
Private Pilot certificate (student pilot caveat except for 12 airfields).
Operable Transponder with altitude reporting capability.
“ATC may immediately authorize a deviation from the altitude reporting equipment requirement; however, a request for a deviation from the 4096 transponder equipment requirement must be submitted to the controlling ATC facility at least one hour before the proposed operation.” - AIM
Appropriate navigation aid for IFR operations.
What is the Mode C Veil?
“The airspace within 30 nautical miles of an airport [with B airspace], from the surface upward to 10,000 feet MSL.”
“Unless otherwise authorized by ATC, aircraft operating within this airspace must be equipped with automatic pressure altitude reporting equipment having Mode C capability.”
Point 1: Note the requirements. DO NOT ENTER WITHOUT SPECIFIC CLEARANCE!!!!!! Clearance is assumed when on an IFR flight plan. Also note the exception for fields that DO NOT ALLOW student certificates.
Point 2: The Mode C veil is ALWAYS active. Transponder is ALWAYS required when within that circle. There are exceptions and requirements to exercise those exceptions.

16. Class “B” Depiction

17. VFR Corridors Definition “E” airspace.
“Airspace through Class B airspace, with defined vertical and lateral boundaries, in which aircraft may operate without an ATC clearance or communication with air traffic control.” – AIM 3-5-7
“E” airspace.
Transit “B” airspace directly over primary airfield.
Typically, no ATC reporting requirements.
“Because of the heavy traffic volume and the procedures necessary to efficiently manage the flow of traffic, it has not been possible to incorporate VFR corridors in the development or modifications of Class B airspace in recent years.”
Point 1: Fewer and fewer of these exist, all the more reason to ensure you understand them.
Point 2: Echo airspace, no entry requirements, per se. Specific airport (i.e. New Orleans) may require clearance. Typically follows a CTAF-type voice-call format.
Point 3: The corridor ALWAYS passes directly over the primary airfield.

18. VFR Corridor Depiction

19. Class “G” Airspace Definition:
“Class G airspace (uncontrolled) is that portion of the airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.”
Exists from the Surface to 1200 feet AGL unless designated otherwise.
Clear of Clouds and 1 SM visibility
“A helicopter may be operated clear of clouds if operated at a speed that allows the pilot adequate opportunity to see any air traffic or obstruction in time to avoid a collision.” FAR (b)
“For the purpose of this section, an aircraft operating at the base altitude of a Class E Airspace area is considered to be within the airspace directly below that area.” FAR (e)
Point 1: Uncontrolled airspace. Surface to 1200 AGL, unless something heavier sits on it.
Point 1b: Basic VFR weather minimums apply, however there is an exception for Helicopters.
Point 1c: Just in case you wanted to split hairs…

20. Class “E” Airspace
I don’t care how many instructors ask, there are not “7 types of Class E airspace.” There is ONE TYPE, PERIOD. It is depicted in 4 different ways, and exists for varying reasons (coincidence? There are 7 basic reasons for it to exist…). Ok, so the AIM has a sentence that says “7 types of Echo airspace are:” Ignore it!
Top: Blue Zipper line: Depicts the change in the floor of Echo airspace.
Second: Magenta dashed: Depicts Echo surface area. Why?
Bottom left: Magenta shaded: Depicts Echo floor at 700 ft AGL. Why?
Bottom Right: Blue shaded: Depicts Echo floor at 1200 ft AGL. Why?

21. Class “E” Airspace All other airspace went UP.
Think of Echo as moving DOWNWARD.
From the AIM:
“Except for 18,000 MSL, Class E airspace has no defined vertical limit but rather it extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace.”
“Unless designated at a lower altitude, Class E airspace begins at 14,500 feet MSL to, but not including, 18,000 feet MSL overlying the 48 contiguous States including the waters within 12 miles from the coast of the 48 contiguous States.”
Or, more simply put:
“Class E airspace exists from 18,000 feet MSL down to 14,500 feet MSL, unless depicted lower, not to include that airspace below 1200 feet AGL.”
Echo airspace flows DOWN. If you think of it this way, it will make everything clear. Compare point 3 and point 4.

22. Class “E” Airspace
A review of the first slide. Compare with the previous official verbiage. Does it make sense now? If not, read the next slide.

23. Class “E” Airspace How is Class “E” Airspace depicted?
Magenta dashed lines
Magenta shaded lines
Blue shaded lines
Blue “zipper” lines
There is ONLY one type of “E” Airspace!!!
Surface area
Surface area extension
Transition areas
En Route Domestic areas
Federal Airways
Offshore Airspace Areas
Otherwise Designated…
Point 1: Already discussed.
Point 2: ONE TYPE of Echo airspace, PERIOD!! Here is why it exists…

24. Class “E” Depicted
Why are there no Blue shaded rings east of the Mississippi? Because the FLOOR of Echo airspace is already down to Out west, the floor is still at 14,500, hence the need for a blue shaded line/circle to bring it down when required.

25. Class “E” Depicted
Note the 5500 MSL depicted in the middle of the chart. What is the floor of Echo airspace to the left of the Zipper line? (1200 AGL)

26. Class “E” Airspace
What are the requirements to operate in Class “E” Airspace?
“No specific certification required.”
“No specific equipment required by the airspace.”
“No specific requirements [for entry or through-flight].”
So why go to the trouble of designating it?
Who why bother?

27. Class “E” Bonus Question
Why do we have all these magenta circles and lines??? Why waste the ink, time, effort?

28. Cloud Clearance Requirements
CLOUD CLEARANCE REQUIREMENTS!!!!!!!!!!!! Typically, 700 ft rings indicate the presence of an IFR approach to that field. Imagine popping out on an IFR approach at 1200 feet, only to find VFR traffic right under your gear? That traffic cannot operate above 700 feet unless it meets the appropriate cloud clearance requirements, which will keep it clear of any IFR traffic dropping out of the clouds. Got it?

29. Normal-Use Airspace Summary
Class B, Class C, Class D, and Class G all go UP. “From the Surface To.”
Class E goes DOWN. “From 18,000 feet MSL down to 14,500 ft MSL, unless depicted lower…”
Each airspace is Individually Tailored.
Don’t forget about Cloud Clearance Requirements!

30. Special Use Airspace HILL MOA Military Operating Area
AIM: “MOA’s consist of airspace of defined vertical and lateral limits established for the purpose of separating certain military training activities from IFR traffic.”
AP/1A: “A MOA is airspace established outside Class A airspace to separate… certain military activities from IFR traffic and to identify for VFR traffic where these activities are conducted.”
AIM: “…Pilots should contact any FSS within 100 miles to obtain accurate real-time information concerning the MOA hours of operation…”
AIM: “Prior to entering an active MOA, pilots should contact the controlling agency for traffic advisories.”
AIM: “Pilots operating under VFR should exercise extreme caution while flying within a MOA when military activity is being conducted…”
Point: Voluntary. In your best interest, though not specifically required.

31. MOA Depicted

32. AND FIXED WING TRAINING
Special Use Airspace
Alert Area
“Alert areas are depicted on aeronautical charts to inform nonparticipating pilots of areas that may contain a high volume of pilot training or an unusual type of aerial activity.”
“…pilots of participating aircraft as well as pilots transiting the area shall be equally responsible for collision avoidance.” – AIM and GP
Again, voluntary.
A-292
CAUTION
HIGH VOLUME OF ROTARY
AND FIXED WING TRAINING
SURFACE TO 17,500

33. Alert Area Depicted

34. Special Use Airspace Warning Area WARNING W-50B
“A warning area is airspace of defined dimensions, extending from three nautical miles outward from the coast of the U. S., that contains activity that may be hazardous to nonparticipating aircraft… A warning area may be located over domestic or international waters or both.”
An off-shore restricted area…
WARNING
W-50B

35. Warning Area Depicted

36. Special Use Airspace Restricted Area RESTRICTED R-6609
“Restricted areas contain airspace identified by an area on the surface of the earth within which the flight of aircraft, while not wholly prohibited, is subject to restriction.”
“Restricted areas denote the existence of unusual, often invisible, hazards to aircraft such as artillery firing, aerial gunnery, or guided missiles.”
“Restricted.” Can operate within, given proper clearance. Clearance can usually be obtained in the air.
“Penetration of restricted areas without authorization from the using or controlling agency may be extremely hazardous to the aircraft and its occupants.”
RESTRICTED
R-6609

37. Restricted Area Depicted

38. Special Use Airspace Prohibited Area Controlling Agency P-56A
Prohibited areas contain airspace of defined dimensions identified by an area on the surface of the earth within which the flight of aircraft is prohibited.”
“Such areas are established for security or other reasons associated with the national welfare.”
Controlling Agency
“NO A/G”
Entry must be coordinated before take-off.
“Prohibited.” Operation is subject to severe scrutiny, though permission may be obtained to operate within. That permission CAN NOT be obtained in the air.
P-56A

39. Prohibited Area Depicted

40. Miscellaneous Airspace
Land-based ADIZ (Washington DC Metropolitan ADIZ)
“Land-based ADIZ are activated and de-activated over U. S. metropolitan areas as needed, with dimensions, activation dates and other relevant information disseminated via NOTAM.”
“In addition to requirements outlined in subparagraphs c1 through c3, pilots operating within a land-based ADIZ must report landing or leaving the land-based ADIZ if flying too low for radar coverage.”
Subparagraph C1
IFR or DVFR flight plan requirement if entering an ADIZ.
Subparagraph C2
Two-way radio requirement
Subparagraph C3
Transponder with Mode C required to be on and set to reply on assigned code.
Don’t get caught busting an ADIZ, HC-2 received several phone calls and attempted flight violations on pilots not aware of the requirements.
- A flight violation received while piloting a military aircraft will not be reported to your civilian flight record.

41. Miscellaneous Airspace
Controlled Firing Areas
Not charted, self-policing. Hazardous activity stops when participating elements detect a non-participating aircraft.
Terminal Radar Service Area (TRSA)
Originally part of the Terminal Radar Program.
Never controlled airspace from regulatory standpoint because it was never subject to the rulemaking process.
Primary airport is Class D airspace. Remaining airspace is Class E as depicted.
AIM: “Pilots operating under VFR are encouraged to contact the radar approach control and avail themselves of the TRSA Services. However, participation is voluntary on the part of the pilot.”

42. TRSA Depiction

43. Miscellaneous Airspace
National Security Areas
“National Security Areas consist of airspace of defined vertical and lateral dimensions established at locations where there is a requirement for increased security and safety of ground facilities.”
“Pilots are requested to voluntarily avoid flying through the depicted NSA.”
Where is this box located? NW of Norfolk, can you find it? What’s there?
NOTICE
FOR REASONS OF NATIONAL
WELFARE, PILOTS ARE REQUESTED
TO AVOID FLIGHT BELOW
2400’ MSL IN THIS AREA

44. National Security Areas

45. Miscellaneous Airspace
Wilderness Areas:
AIM: “Pilots are requested to maintain a minimum altitude of 2,000 feet above the surface of the following: National Parks, Monuments, Seashores, Lakeshores, Recreation areas and Scenic River-ways… Wildlife Refuges, Big Game Refuges, Game Ranges, Wildlife Ranges, and Wilderness and Primitive areas. ” – AIM 7-4-6
3710 (Ch 5.5): “[Noise Sensitive and Wilderness Areas] shall be avoided when at altitudes of less than 3,000 feet AGL except when in compliance with an approved:
Traffic or approach pattern
VR or IR route
Special use airspace.”
Note the difference between FAR/AIM and OPNAV 3710.

46. Wilderness Area

47. Conclusion
Questions?