Airspace Classes
The airspace is divided into three dimensional sections, called classes. The purpose of this classification system is to precisely set out
which flight rules apply and what interaction is defined between aircraft and ATC (Air Traffic Control). The Airspace Classes are
defined by the International Civil Aviation Organization (ICAO) and most countries use this system (although some nations have
deviations that are closer to the flight rules that existed before ICAO standardisation). In the following table, you will find an
overview of the Classes and their definitions. Note that in some countries, not all classes are actually used (i.e. have not been
implemented into legislation).
|
Class |
Flight Rules |
Clearance |
Aircraft separation |
|
A |
IFR or SVFR |
ATC Clearance |
Separation by ATC |
|
B |
IFR, SVFR or VFR |
ATC Clearance |
Separation by ATC |
|
C |
IFR, SVFR or VFR |
ATC Clearance |
Aircraft operating under IFR and SVFR are separated from each other and from flights
operating under VFR. Flights operating under VFR are given traffic information about other VFR flights.
|
|
D |
IFR, SVFR or VFR |
ATC Clearance |
Aircraft operating under IFR and SVFR are separated from each other, and are given
traffic information about VFR flights. Flights operating under VFR are given
traffic information in respect of all other flights.
|
|
E |
IFR, SVFR or VFR |
ATC Clearance only for IFR and SVFR |
Aircraft operating under IFR and SVFR are separated from each other. As far as is
practical, traffic information is given to all flights about VFR flights.
|
|
F |
IFR or VFR |
No clearances |
ATC separation for IFR, as far as practical. Traffic information may be given as
about other flights. |
|
G |
IFR or VFR |
No clearances |
No ATC separation. Traffic information may be given as far as practical about other flights. |
Classes A to E are referred to as controlled airspace. Classes F and G are uncontrolled airspace. Note that class F is not used in the United States of America, Germany
and Australia. Furthermore, every country can, and will, have its own deviations, so when
flying you must be familiar with the airspace rules and procedures of the specific
country.
VFR weather minimums
When flying under Visual Flights Rules, there are requirements regarding the distance you should keep from clouds and flight visibility minimums.
These visual minimum conditions are designed so that pilots are able to avoid collisions with other aircraft by acting on the 'see and avoid'
principle. However, to be able to spot an airplane emerging from a cloud and be able to react to it, you must be a minimum distance from it.
Note that aircraft separation under VFR conditions is always the responsibility of the VFR pilot!
|
Class |
Flight visibility (miles) |
Distance from clouds (miles) |
|
A |
Not applicable |
Not applicable |
|
B |
3 |
Clear of clouds |
|
C |
3 |
500 feet below, 1000 feet above, 2000 feet horizontal |
|
D |
3 |
500 feet below, 1000 feet above, 2000 feet horizontal |
|
E |
3 (less than 10,000 feet msl)
5 (at or above 10,000 feet msl) |
500 feet below, 1000 feet above, 2000 feet horizontal
1000 feet below, 1000 feet above, 1 mile horizontal |
|
F |
|
|
|
G |
1 (Day and below 1200 feet agl)
3 (Night and below 1200 feet agl)
1 (Day and above 1200 feet agl and less the 10,000 feet msl)
3 (Night and above 1200 feet agl and less the 10,000 feet msl)
5 (Above 1200 feet agl and above 10,000 feet msl) |
Clear of clouds
500 feet below, 1000 feet above, 2000 feet horizontal
500 feet below, 1000 feet above, 2000 feet horizontal
500 feet below, 1000 feet above, 2000 feet horizontal
1000 feet below, 1000 feet above, 1 mile horizontal |
Note : In Class G Airspace, below 1,200 feet above the surface, a helicopter
may be operated clear of clouds if flying at a speed that allows the pilot adequate
opportunity to see any air traffic or obstruction in time to avoid a collision (FAR).
References
ICAO Annex two (Rules of the Air) and annex 11 (ATC Services). When flying in International
airspace the Annex two (Rules of the Air) is the guiding document.
Every country must publish its ATC system, and deviations from the ICAO standards.
The two manuals used in the USA are the International Flight Information Manual
and the Aeronautical Information Publication.
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