Airspace class

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The world's navigable airspace is divided into three-dimensional segments, each of which is assigned to a specific class. Most nations adhere to the classification specified by the International Civil Aviation Organization (ICAO) and described below, though they might use only some of the classes defined below, and significantly alter the exact rules and requirements. Similarly, individual nations may also designate special use airspace (SUA) with further rules for reasons of national security or safety.

Contents

Abbreviations used in this article

AbbreviationFull nameDescription
ATC Air traffic control A service provided by ground-based controllers who direct aircraft on the ground and through controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots.
ATSAir Traffic ServiceA generic term meaning variously, flight information service, alerting service, air traffic advisory service, air traffic control service (area control service, approach control service or aerodrome control service).
ATZAerodrome traffic zoneCircular zones around an airport with a radius based on the length of the runway
CTA Control area A controlled airspace which extends from a lower limit to an upper limit.
CTR Control Zone A controlled airspace extending upwards from the surface to an upper limit.
FLxxx (or FL xxx) Flight level Defined as a vertical altitude at standard atmospheric pressure, nominally expressed in hundreds of feet. Flight levels are usually designated in writing as FLxxx, where xxx is a two or three-digit number indicating the pressure altitude in units of 100 feet. In radio communications, FL290 (29,000 ft; 8,850 m) would be pronounced as "flight level two nine(r) zero." The phrase "flight level" makes it clear that this refers to the standardized pressure altitude.
ICAO International Civil Aviation Organization A specialized agency of the United Nations. It codifies the principles and techniques of international air navigation and fosters the planning and development of international air transport to ensure safe and orderly growth
IFR Instrument flight rules A set of regulations that concern flying by reference to instruments in the flight deck, and where navigation is accomplished by reference to electronic signals.
MATZ Military aerodrome traffic zone A version of ATZ for military air bases.
SVFR Special visual flight rules A set of aviation regulations under which a pilot may operate an aircraft. It's a special case of operating under visual flight rules (VFR) where a VFR flight is cleared by air traffic control to operate within a control zone in meteorological conditions that are poorer than visual meteorological conditions.
TCA Terminal control area A control area normally established at the confluence of ATS Routes in the vicinity of one or more major aerodromes.
TMA Terminal maneuvering area A designated area of controlled airspace surrounding a major airport where there is a high volume of traffic.
TRSA Terminal radar service area A delimited airspace in which radar and air traffic control services are made available to pilots flying under instrument flight rules or (optionally) visual flight rules for the purposes of maintaining aircraft separation.
VFR Visual flight rules A set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going

ICAO definitions

On March 12, 1990, ICAO adopted the current airspace classification scheme. [1] The classes are fundamentally defined in terms of flight rules and interactions between aircraft and air traffic control (ATC). Generally speaking, the ICAO airspaces allocate the responsibility for avoiding other aircraft, namely either to ATC (if separation is provided) or to the aircraft commander (if not).

Some key concepts are:

ICAO adopted classifications

Note: These are the ICAO definitions. Country-specific adaptations (such as "two-way communications" instead of "clearance" for Class C in the US) are discussed in the sections below.

Special Airspace: these may limit pilot operation in certain areas. These consist of Prohibited areas, Restricted areas, Warning Areas, MOAs (military operation areas), Alert areas and Controlled firing areas (CFAs), all of which can be found on the flight charts.

Classes A–E are referred to as controlled airspace. Classes F and G are uncontrolled airspace.

The table below provides an overview of the above classes, and the specifications for each.

Class Controlled IFR SVFR VFR ATC clearanceSeparationTraffic information
AControlledYesNoNoRequiredProvided for all flightsN/A
BControlledYesYesYesRequiredProvided for all flightsN/A
CControlledYesYesYesRequiredProvided for all IFR/SVFR to IFR/SVFR/VFRProvided for all VFR
DControlledYesYesYesRequiredProvided for IFR/SVFR to other IFR/SVFRProvided for all IFR and VFR
EControlledYesYesYesRequired for IFR and SVFRProvided for IFR/SVFR to other IFR/SVFRProvided for all IFR and VFR flights where possible
FUncontrolledYesNoYesAdvisory onlyProvided for IFR/SVFR to other IFR/SVFR where possibleProvided where possible if requested
GUncontrolledYesNoYesNot providedNot providedProvided where possible if requested

Use of airspace classes

Each national aviation authority determines how it uses the ICAO classifications in its airspace design. In some countries, the rules are modified slightly to fit the airspace rules and air traffic services that existed before the ICAO standardisation.

Australia

Australia has adopted a civil airspace system based on the United States National Airspace System (NAS):

Transition from GAAP to Class D

Australia used to have a non-standard class of airspace for use at the capital city general aviation airports, called a General Aviation Airport Procedures Zone (GAAP Zone). A control tower provided procedural clearances for all aircraft inside the zone. Additionally, any aircraft operating within 5 nmi (9.3 km; 5.8 mi) of the zone must obtain a clearance. VFR aircraft arrive and depart using standard arrival and departure routes, while instrument arrival and departure procedures are published for IFR operations. During visual meteorological conditions (VMC), IFR aircraft are not provided with full IFR services. During instrument meteorological conditions (IMC), or marginal VMC, VFR operations are restricted in order to facilitate full IFR service for IFR aircraft.

In June 2010, all GAAP aerodromes were changed to Class D aerodromes, and the previous Class D procedures were changed. The new Class D procedures are similar to the FAA Class D procedures. VFR aircraft are no longer required to enter the airspace via set inbound/outbound points, however can be directed there by ATC. VFR and IFR aircraft now require taxi clearance in the "manoeuvring area" of the aerodrome, but can still taxi within set apron areas without a clearance. IFR aircraft now receive slot times and the visibility requirements of Special VFR are reduced from 3000m visibility to 1600m.

Canada

There are seven airspace classes in use in Canada (letters A through G), but the letters do not always correspond with ICAO definitions.

Denmark

Estonia

In Estonia, airspace is divided into only classes C, D and G. [2]

France

In France, Classes B and F are not used at all. Airspace is divided into lower airspace below FL195 (19,500 ft; 5,950 m) and upper airspace above FL195 (19,500 ft; 5,950 m) .

Germany

In Germany, Classes A, B, and F are not used at all. Airspace is divided into lower airspace below FL245 (24,500 ft; 7,450 m) and upper airspace above FL245 (24,500 ft; 7,450 m) .

Iraq

In Iraq, the Flight Information Regions (FIR) is known as Baghdad FIR. It is classified into Class A, D, E and G airspace. Class B, C and F airspace are not used in the Baghdad FIR. Air traffic services are provided in all controlled airspace, by the controlling ATC Unit, based on an ATS Surveillance System (supplemented by procedural non-ATS Surveillance System procedures) or MRU where authorized based on Procedural (non- ATC Surveillance System) procedures and supplemented by ATC Surveillance System where possible.

Ireland

In Ireland, airspace is divided into classes A, C and G only. [3]

Italy

Kenya

Classes A, C, D, G are used in Kenyan airspace, alongside unclassified military operation areas which are defined in Restricted Areas and Prohibited Areas, and are controlled by military air traffic control units.

Lithuania

In Lithuania, Classes A and B are generally not used at all. Classes C and D are used in the following areas of controlled airspace of the Republic of Lithuania:

Mauritius

Classes A, C and G are used in Mauritius. [6]

Netherlands

In the Netherlands, a relatively large part of the country is Class A airspace. Near Amsterdam, the capital of the Netherlands, the airspace is almost completely built up with class A. It starts at 1,500 ft (460 m) MSL, and ends at FL195 (19,500 ft; 5,950 m) . Further away from Amsterdam and its airport Schiphol, Class A starts at a higher altitude. Class B is used a lot as well. Anywhere in the Netherlands, Class A airspace ends at FL195 (19,500 ft; 5,950 m) and changes into Class C. Most of the CTRs are class D, some of them are class C. Class F is the only class that cannot be found in the Dutch airspace. [7]

New Zealand

In New Zealand, Classes B, E and F are not used at all. Class A is used in Oceanic airspace above FL245 (24,500 ft; 7,450 m) whereas Classes C and D are used in domestic airspace as part of the New Zealand FIR. [8]

Norway

In Norway, airspace is divided into classes A, C, D and G. [9]

Russia

Russia adopted a modified version of ICAO airspace classification on November 1, 2010. The division into classes for the airspace of the Russian Federation was introduced for the first time in the history of Russia. [10]

The airspace above the territory of the Russian Federation is divided as follows:

Airspace controlled by Russia outside the territory of Russia has different division into classes and includes redefined Class A and Class G, but no class C airspace. [11]

Specific boundaries of airspaces are determined by the Order of the Ministry of Transport of the Russian Federation #199 of September 15, 2010. [11] [12]

Sweden

In Sweden, airspace is divided into airspace class C and G only with a small E class area stretching over the Danish border into Swedish airspace. [13]

United Kingdom

  • Class A:
    • Most airways up to FL195 (19,500 ft; 5,950 m) with the exception of airways lying within the Belfast CTR/TMA and around Scotland.
    • The Terminal Control Areas (TMAs) around London Heathrow Airport, Birmingham and Manchester.
    • The Channel Island Zone is Class A above FL080 (8,000 ft; 2,450 m) .
    • The CTAs of Daventry, Clacton, Cotswold and Worthing.
    Airways typically start at FL070 (7,000 ft; 2,150 m) and routing options become more attractive above FL140 (14,000 ft; 4,250 m) .
  • Class B: Not currently used in the UK.
  • Class C: All UK airspace between FL195 (19,500 ft; 5,950 m) and FL660 (66,000 ft; 20,100 m) . (The Upper Flight Information Region (UIR) boundary begins at FL245 (24,500 ft; 7,450 m) .)

    Some airways and CTAs may have sections of Class C.

  • Class D: The CTRs and CTAs around the busier airports such as Stansted, Gatwick, Glasgow, Birmingham, Jersey, Manchester and Heathrow. A few airways in less busy areas are class D, allowing mid-level military VFR flights.
  • Class E: Parts of the Belfast TMA and ATS routes in Scotland. A clearance is not required for VFR flights within Class E airspace, however pilots are strongly advised to contact the appropriate ATS.
  • Class F: Not currently used in the UK. All remaining Class F airspace was removed or converted to Class E or G in November 2014.
  • Class G: All remaining airspace, comprising by far the largest part of the airspace below FL195 (19,500 ft; 5,950 m) . The UK is unusual in that it has not adopted a widespread class E system of airways for most airspace lower than FL070 (7,000 ft; 2,150 m) . Therefore, for light aircraft, IFR flight in Class G airspace is relatively common. Use of a radio or transponder is not required, even in IMC. [15] ATC units may provide an "as far as practical" form of separation between some such flights, but participation in the service is voluntary. [16]

In addition the UK has a couple of special classes of airspace that do not fall within the ICAO classes:

United States

Airspace classes in the United States Airspace classes (United States).png
Airspace classes in the United States

The U.S. adopted a slightly modified version of the ICAO system on September 16, 1993, when regions of airspace designated according to older classifications were converted entirely. The exceptions are some terminal radar service areas (TRSA), which have special rules and still exist in a few places.

Airspace classes and Visual Flight Rules

Authorities use the ICAO definitions to derive additional rules for Visual Flight Rules (VFR) cloud clearance, visibility, and equipment requirements.

For example, consider Class E airspace. It is possible that an aircraft operating under VFR is not in communication with ATC, so it is imperative that its pilot be able to see and avoid other aircraft (and vice versa). That includes IFR flights emerging from a cloud, so the VFR flight must keep a designated distance from the edges of clouds above, below, and laterally, and must maintain at least a designated visibility, to give the two aircraft time to observe and avoid each other. The low-level speed limit of 250 knots (460 km/h; 290 mph) does not apply above 10,000 feet (3,000 m), so the visibility requirements are higher.

On the other hand, in Class B and Class C airspaces, separation is provided by ATC to all aircraft. In these situations the VFR pilot only needs to see where his/her own aircraft is going, so visibility requirements are less stringent, and there is no designated minimum distance from clouds.

Similar considerations determine whether a VFR aircraft must use a two-way radio and/or a transponder.

Special use airspace

Each national authority designates areas of special use airspace (SUA), primarily for reasons of national security. This is not a separate classification from the ATC-based classes; each piece of SUA is contained in one or more zones of letter-classed airspace.

SUAs range in restrictiveness, from areas where flight is always prohibited except to authorized aircraft, to areas that are not charted but are used by military for potentially hazardous operations (in this case, the onus is on the military personnel to avoid conflict). Refer to the external links for more specific details.

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<span class="mw-page-title-main">Instrument flight rules</span> Civil aviation regulations for flight on instruments

In aviation, instrument flight rules (IFR) is one of two sets of regulations governing all aspects of civil aviation aircraft operations; the other is visual flight rules (VFR).

In aviation, visual flight rules (VFR) are a set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minima, i.e., in visual meteorological conditions (VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate the aircraft with visual reference to the ground, and by visually avoiding obstructions and other aircraft.

<span class="mw-page-title-main">Air traffic control</span> Public service provided for the purpose of maintaining the safe and orderly flow of air traffic

Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airspace. The primary purpose of ATC worldwide is to prevent collisions, organize and expedite the flow of air traffic, and provide information and other support for pilots.

In aviation, uncontrolled airspace is airspace in which an Air Traffic Control (ATC) service is not deemed necessary or cannot be provided for practical reasons. It is the opposite of controlled airspace. It is that portion of the airspace that has not been designated as Control Area, Control Zone, Terminal Control Area or Transition Area.

<span class="mw-page-title-main">Controlled airspace</span> Areas served by air traffic control

Controlled airspace is airspace of defined dimensions within which air traffic control (ATC) services are provided. The level of control varies with different classes of airspace. Controlled airspace usually imposes higher weather minimums than are applicable in uncontrolled airspace. It is the opposite of uncontrolled airspace.

Airspace is the portion of the atmosphere controlled by a country above its territory, including its territorial waters or, more generally, any specific three-dimensional portion of the atmosphere. It is not the same as outer space which is the expanse or space outside the Earth and aerospace which is the general term for Earth's atmosphere and the outer space within the planet's vicinity. History:

<span class="mw-page-title-main">Visual meteorological conditions</span> Flight category allowing pilots to fly using vision as well as instruments

In aviation, visual meteorological conditions (VMC) is an aviation flight category in which visual flight rules (VFR) flight is permitted—that is, conditions in which pilots have sufficient visibility to fly the aircraft maintaining visual separation from terrain and other aircraft. They are the opposite of instrument meteorological conditions (IMC). The boundary criteria between IMC and VMC are known as the VMC minima and are defined by: visibility, cloud ceilings, and cloud clearances.

<span class="mw-page-title-main">Flight plan</span> Document filed by a pilot or flight dispatcher indicating the aircrafts flight path

Flight plans are documents filed by a pilot or flight dispatcher with the local Air Navigation Service Provider prior to departure which indicate the plane's planned route or flight path. Flight plan format is specified in ICAO Doc 4444. They generally include basic information such as departure and arrival points, estimated time en route, alternate airports in case of bad weather, type of flight, the pilot's information, number of people on board, and information about the aircraft itself. In most countries, flight plans are required for flights under IFR, but may be optional for flying VFR unless crossing international borders. Flight plans are highly recommended, especially when flying over inhospitable areas such as water, as they provide a way of alerting rescuers if the flight is overdue. In the United States and Canada, when an aircraft is crossing the Air Defense Identification Zone (ADIZ), either an IFR or a special type of VFR flight plan called a DVFR flight plan must be filed. For IFR flights, flight plans are used by air traffic control to initiate tracking and routing services. For VFR flights, their only purpose is to provide needed information should search and rescue operations be required, or for use by air traffic control when flying in a "Special Flight Rules Area."

<span class="mw-page-title-main">Canadian airspace</span>

Canadian airspace is the region of airspace above the surface of the Earth within which Canada has jurisdiction. It falls within a region roughly defined as either the Canadian land mass, the Canadian Arctic or the Canadian archipelago, and areas of the high seas. Airspace is managed by Transport Canada and detailed information regarding exact dimensions and classification is available in the Designated Airspace Handbook which is published every fifty-six days by Nav Canada.

Special visual flight rules are a set of aviation regulations under which a pilot may operate an aircraft. It is a special case of operating under visual flight rules (VFR).

A flight information service (FIS) is a form of air traffic service which is available to any aircraft within a flight information region (FIR), as agreed internationally by ICAO.

<span class="mw-page-title-main">Allegheny Airlines Flight 853</span> 1969 mid-air collision

Allegheny Airlines Flight 853 was a regularly scheduled Allegheny Airlines flight from Boston, Massachusetts, to St. Louis, Missouri, with stops in Baltimore, Maryland, Cincinnati, Ohio, and Indianapolis, Indiana. On September 9, 1969, the aircraft serving the flight, a McDonnell Douglas DC-9, collided in mid-air with a Piper PA-28 light aircraft near Fairland, Indiana. The DC-9 was carrying 78 passengers and 4 crew members, and the Piper was leased to a student pilot on a solo cross-country flight. All 83 occupants of both aircraft were killed in the accident and both aircraft were destroyed.

In aviation, a control zone (CTR) is a volume of controlled airspace, usually situated below a control area, normally around an airport, which extends from the surface to a specified upper limit, established to protect air traffic operating to and from that airport. Because CTRs are, by definition, controlled airspace, aircraft can only fly in it after receiving a specific clearance from air traffic control. This means that air traffic control at the airport know exactly which aircraft are in that airspace, and can take steps to ensure aircraft are aware of each other, either using separation or by passing traffic information.

<span class="mw-page-title-main">Non-towered airport</span> Airport without an air traffic control tower

In aviation, a non-towered airport is an airport without a control tower, or air traffic control (ATC) unit. The vast majority of the world's airports are non-towered. In the United States, there are close to 20,000 non-towered airports compared to approximately 500 airports with control towers. Airports with a control tower without 24/7 ATC service follow non-towered airport procedures when the tower is closed but the airport remains open, for example at night.

In aviation, a terminal control area, is a designated area of controlled airspace surrounding a major airport where there is a high volume of traffic. TMA airspace is normally designed in a circular configuration centered on the airport, and differs from a control area in that it includes several levels of increasingly larger areas, creating an "upside-down wedding cake" shape.

<span class="mw-page-title-main">Airspace class (United States)</span> U.S. airspace system classification scheme

The United States airspace system's classification scheme is intended to maximize pilot flexibility within acceptable levels of risk appropriate to the type of operation and traffic density within that class of airspace – in particular to provide separation and active control in areas of dense or high-speed flight operations.

The National Airspace System (NAS) is the airspace, navigation facilities and airports of the United States along with their associated information, services, rules, regulations, policies, procedures, personnel and equipment. It includes components shared jointly with the military. It is one of the most complex aviation systems in the world, and services air travel in the United States and over large portions of the world's oceans.

Montreal Area Control Centre is one of 7 Area Control Centres in Canada operated by Nav Canada. Montreal ACC is located in a building on the outskirts of Montréal–Pierre Elliott Trudeau International Airport.

<span class="mw-page-title-main">London Area Control Centre</span> Air traffic control facility

The London Area Control Centre (LACC) is an air traffic control centre based at Swanwick near Fareham in Hampshire, southern England. It is operated by National Air Traffic Services (NATS), starting operations on 27 January 2002, and handles aircraft over much of England and Wales. The Swanwick facility replaces that of the former site at West Drayton.

Toronto Area Control Center is one of seven area control centers in Canada operated by Nav Canada. The Toronto Area Control Centre is based near Toronto Pearson International Airport in Mississauga, Ontario.

References

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  2. "eAIS Estonia, Part 2, ENR 1.4", eaip.eans.ee, 8 June 2017, archived from the original on 8 July 2017, retrieved 14 July 2017
  3. "Guide to IAA ATM Operations" (PDF), www.iaa.ie, 22 October 2014, retrieved 12 April 2020
  4. 1 2 "ENR 2.2 - OTHER REGULATED AIRSPACE" (PDF). Irish Aviation Authority. 2022-10-06. Retrieved 15 February 2024.
  5. Airfield Guide Lithuania, 29 SEP 2005, ENR 1.1-1 Archived 2006-10-14 at the Wayback Machine
  6. AIP Mauritius
  7. "AIS-publicaties". Air Traffic Control Netherlands. Retrieved 2022-05-02.
  8. "New Zealand Airspace" (PDF). Civil Aviation Authority of New Zealand.
  9. IPPC AIP, AIP.
  10. The Official Site of the Prime Minister of the Russian Federation, March 11, 2010.
  11. 1 2 3 4 5 Appendix to the Resolution of the Government of The Russian Federation #138 of March 11, 2010. Archived July 24, 2011, at the Wayback Machine (in Russian)
  12. Order of the Ministry of Transport of the Russian Federation #199 of September 15, 2010. (in Russian)
  13. "ATS airspace classes – services provided and flight requirements". aro.lfv.se. Archived from the original on 2022-04-07.
  14. "Area Chart - Malmö". Archived from the original on 2020-10-20. Retrieved 2020-10-15.
  15. "UK ATS Airspace Classifications" (PDF). Archived from the original (PDF) on 2011-06-06. Retrieved 2010-01-22.
  16. "New Air Traffic Services Outside Controlled Airspace (ATSOCAS) interactive guide now available". Air Space Safety. Airspace & Safety Initiative (ASI). 20 June 2008. Archived from the original on January 3, 2010.
  17. Godwin, Peter (1987–2004). The Air Pilot's Manual: Aviation Law And Meteorology. Cranfield, England: Air Pilot Publishing Ltd.
  18. 1 2 FAA Order 7400.11, Subpart E, Para. 6001
  19. "Pilot2Pilot – For Pilots by Pilot: Class B Airspace". Pilot2pilotblog.blogspot.com. Retrieved 2014-03-04.