C airspace in the USA

[karrank]

FAA AIM 3-2-4. Class C Airspace

a. Definition. 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. Although the configuration of each Class C airspace area is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends no lower than 1,200 feet up to 4,000 feet above the airport elevation.

So it goes up to 4,000FT AGL. Any uninformed minister or other idiot who based decisions or directions regarding airspace established only above 4,500FT AMSL on the US system is not being relevant or helpful.

4. Though not requiring regulatory action, Class C airspace areas have a procedural Outer Area. Normally this area is 20 NM from the primary Class C airspace airport. Its vertical limit extends from the lower limits of radio/radar coverage up to the ceiling of the approach control's delegated airspace, excluding the Class C airspace itself, and other airspace as appropriate.

This is a mysterious one, but seems to imply the C airspace of any unit is not just the tiny bit shown on the map (and slated for here) but also an amorphous mass around it. Maybe the size of tower airspace in YMMM FIR?

e. Aircraft Separation. Separation is provided within the Class C airspace and the outer area after two-way radio communications and radar contact are established. VFR aircraft are separated from IFR aircraft within the Class C airspace by any of the following:

1. Visual separation.

2. 500 feet vertical; except when operating beneath a heavy jet.

3. Target resolution.

NOTE-
1. Separation and sequencing of VFR aircraft will be suspended in the event of a radar outage as this service is dependent on radar. The pilot will be advised that the service is not available and issued wind, runway information and the time or place to contact the tower.

So, if the radar is not working, not installed or the transponders fritzed they get the same service as THE INDUSTRY OPTION!!! Maybe that wasn't the sad bastard of an option as everybody thought and is more closely based on the US model than anything Dick came up with???

And this is the section that makes it plain US ATC is incapable of applying procedural separation to VFR, no such limitation applies here.

Read it yourself at With a nice Vimy picture - FAA AIM

PS. Also note all their documents are on show, with a link from the FAA home page, and you can cut'n'paste and everything...

[Bevan666]

I think the 'Outer Area' is a mode C veil around the class C (or B) airspace. In the US there are a handful (~10) of Class B airspace areas, and about 30 odd class C airspace zones, the rest is *gasp* D and E.

Above class C, you mostly have *gasp* class E (with NO transponder requirement).

I will verify on my copy of the AIM and charts when I get home next.

Bevan..

[halfmoon]

The "mode C veil" is always around class B airspace only(30nm arc). If you don't have a transponder then its a no go.
Class C airspace does not have a mode C veil, you can transit or land at a class c airport with prior notification if you have no transponder. VFR-VFR seperation does not exist in the USA. However, VFR-IFR seperation does exist.
VFR a/c can not fly into class E airpace when below the meteorological mins stated in the FARAIM (similiar to australia meteorological mins). This means that the only time they are in class E airspace is during VMC DAY OR NIGHT.. therefore SEE AND AVOID.

[druglord]

I think there's a lot more than 10 class B's and 20 class C's.