Update: removed Le Bourget.
ICAO Class A (“class alfa”) airspace is the strictest of all, allowing only IFR operations (without special permission). In the U.S. and southern Canada, most airspace between FL180 and FL600 is class A (the floor is higher as you get further north in Canada).
Even the busiest airports rarely designate their control zones as class A: the U.S., for example, contains 15 of the world’s 30 busiest airports by passenger traffic, but they are designated only Class B (“class bravo”), so routine controlled VFR operations are still permitted (I’ve flown my warrior into some of them, IFR and VFR).
Around the world, however, there exists a tiny handful of Class A airports. Here are the Class A airports I know about so far:
- Ben Gurion International Airport, Tel Aviv, Israel
- Charles de Gaulle International Airport, Paris, France
- El Dorado International Airport, Bogatá, Columbia
- Gibraltar Airport, Gibraltar
- Heathrow Airport, London, UK
Le Bourget Airport, Paris, France
- Orly Airport, Paris, France
There appears to be no single reason for the designation — it’s certainly not due to traffic alone. Tel Aviv is probably Class A for security reasons, being so near hostile soil, and Bogatá’s designation may have something to do with drug smuggling. Heathrow is busy (though not as busy as some U.S. airports), but it also operates in very confined airspace. Gibraltar has about three scheduled flights a day — go figure. (It’s near the Spanish border, but many major airports operate very close to international borders; many busy airports also operate near high terrain).
Le Bourget has no scheduled flights at all, but Parisians are Parisians, and zut alors! if London has one Class A airport, Paris will show them by having three .
Reagan National Airport in Washington DC has additional restrictions that make it similar to Class A, but is still designated Class B. Does anyone know of any other Class A airports that I’ve missed?