LAW 004

Airspace

Division of airspace

Every part of the world is split into FIRs (Flight Information Regions). The country in charge of each region provides the services there. Airspace over the oceans is covered the same way: each oceanic FIR is assigned to a country. Some regions are divided into an upper and a lower part: the upper part is the UIR (Upper Flight Information Region), and the lower part keeps the name FIR.

The unit of division

FIR

Flight Information Region. An airspace of defined dimensions within which flight information service and alerting service are provided.

Flight Information Region

Controlled airspaceA–E

CTAControl areas

TMATerminal areas

CTRControl zonesNever E

AWYAirway

Uncontrolled airspaceF*–G

FIZFlight information zones

Listed separatelyP-areaR-areaD-areaTRATSA

The FIR splits into controlled and uncontrolled airspace. Special areas are listed separately.

The same airspace seen from the side. The controlled airspace over the aerodrome is one continuous stack: the CTR runs from the surface up to the base of the TMA, and the TMA up to the base of the CTA above it. Only the CTR touches the ground, because a CTA extends upwards from a specified limit above the earth. The FIZ and the ATZ reach the ground as well, but neither is controlled airspace, and the sky outside every drawn volume is uncontrolled.

Bluecontrolled airspace, A–E
Teal and tana zone that is not controlled
Red, orange and golda special area
Open skyuncontrolled airspace, F*–G

Redrawn from the course deck’s own Division of Airspace slide, and not to scale. The geometry agrees with the definitions: ICAO Annex 11 for the CTR and the CTA, Annex 2 for the TMA, and ICAO Doc 8400 for every expansion.

*Class F is not to be used as a permanent classification. Service in Class F airspace cannot be provided by FISOs.

Controlled and uncontrolled airspace

Who carries itControlledA–E

ATC issues the clearances and carries the separation. The pilot-in-command still holds final authority, and VFR traffic is still seeing and avoiding.

Who carries itUncontrolledF*–G

The responsibility is on the pilots.

Flight rules

IFRInstrument Flight RulesNormally flown in controlled airspace.

VFRVisual Flight RulesUsually flown outside controlled airspace, but allowed inside it too.

Meteorological conditions

IMCInstrument Meteorological ConditionsVisibility and distance from cloud below the VMC minima.

VMCVisual Meteorological ConditionsVFR flights have to stay in these.

Controlled airspace types

Reaches the groundCTRA–D, never E

Control Zone. Extends from the ground up to an upper limit.

Never reaches the groundCTAA–E

Control Area. The umbrella term: controlled airspace that does not reach the ground, but extends upwards from a specified limit.

Types of CTA

A TMA is one type of CTA, not the other way round.

TMATerminal Control AreaA–E

Above the CTRs.

OCAOceanic Control AreaA–E

UTAUpper Control AreaA–E

AWYAirwayA–E

A CTA shaped like a corridor. Aircraft have to stay on it. Usually extends 5 NM to either side of the centreline. Slowly being replaced by RNAV routes and free route airspace, and not used in most of the EU.

TMA, AWY, OCA and UTA are all types of CTA.

Zones around aerodromes

FIZFlight Information Zone

Not a controlled zone. Only FIS, not ATC.

FIS only

TIZ / TIATraffic Information Zone / Area

The same airspace under another name. Denmark called it TIZ and TIA until the early 2020s and now says FIZ, as Finland does; Norway and Sweden still say TIZ and TIA. No ICAO or EU rule fixes the name.

Same as a FIZ

ATZAerodrome Traffic Zone

Not a controlled zone. Rarely used, around airfields without a tower. Pilots communicate with each other independently.

Pilots self-inform

Controlled aerodrome

No zone. ATC service is provided, but only to aerodrome traffic.

ATC

Airspace classification

Every area gets a class, so the rules match the type of airspace and the traffic in it.

Each class describes

Level of separation

Permitted flights

Communication required

Services provided

Which classes go where

ABCDEFG No VFR CTR A–DTMA A–EAWY A–ECTA A–EUncontrolled F–G

ControlledUncontrolled

A–E are controlled, F–G are uncontrolled.

Where two classes meet, the level they share follows the least restrictive of the two.

The ruleChanging class

When two airspaces of different classes meet vertically (one on top of the other), flights at the shared level comply with the least restrictive class.

Where each class is used

AClass ANo VFRControlled

The most restrictive class, geared to commercial traffic. Normally only very busy CTRs and TMAs, and high levels where SERA does not allow VFR: above FL 285 in RVSM (Reduced Vertical Separation Minimum) airspace. Also used in the oceanic FIRs: Bodø, Reykjavík and Nuuk.

BClass BControlled

Not used in many countries. Mainly larger TMAs.

CClass CControlled

SERA classifies all airspace above FL 195 as Class C. Below that, each Member State classifies its airspace to suit its own needs. A popular classification for en-route airspace, TMAs and CTRs.

DClass DControlled

Mainly control zones, and sometimes TMAs.

EClass EControlled

Less restrictive than D. Fewer flights are separated or controlled, which gives VFR traffic more freedom.

FClass FUncontrolled

A temporary measure, until another classification can replace it. Only used where the air traffic services on hand cannot provide ATC, and the limited collision-hazard advice from FIS is not enough on its own.

Duration: Stated in the Member State’s AIP, and should not be longer than 3 years.
Daily change: A CTR may switch class on a daily schedule, for example Class A from 06:00 to 20:00 and Class F overnight. Also for no longer than 3 years.

GClass GUncontrolled

Uncontrolled airspace: FIS aerodromes and en-route airspace without ATC.

Class explorer

From SERA Appendix 4. Pick flight rules and a class.

SERA Appendix 4

Class C, VFRControlled

Separation: VFR ↔ IFR
Service: ATC for separation. Traffic information for VFR/VFR. Avoidance advice on request.
Speed limit: 250 kt below 10 000 ft
Radio equipment: Required
Continuous 2-way radio: Required
ATC clearance: Required

Radio and clearance at a glance

SERA Appendix 4

	A	B	C	D	E	F	G
VFR
Radio equipment	–	Required	Required	Required	Not required	Not required	Not required
Continuous 2-way	–	Required	Required	Required	Not required	Not required	Not required
Clearance	–	Required	Required	Required	Not required	Not required	Not required
IFR
Radio equipment	Required	Required	Required	Required	Required	Required	Required
Continuous 2-way	Required	Required	Required	Required	Required	Not required	Not required
Clearance	Required	Required	Required	Required	Required	Not required	Not required

– = VFR not allowed in Class A.

Speed limit in full: 250 kt IAS below 3 050 m (10 000 ft) AMSL. Where the transition altitude is lower than that, FL 100 is used instead of 10 000 ft. (SERA Appendix 4)

VMC minima

Applies in airspace classes B–G.

How far from clouds you must stay, and how far you must be able to see.

1 000 ftabove and below clouds

1 500 mhorizontally away from clouds

8 kmvisibility at and above FL 100 (10 000 ft)

5 kmvisibility below FL 100 (10 000 ft)

Why FL 100: SERA puts the break at 3 050 m (10 000 ft) AMSL, and FL 100 is used instead wherever the transition altitude is lower than that, because up there, above the transition level, levels are flight levels. Denmark’s is 3 000 or 5 000 ft, so in Denmark the break is FL 100. The transition altitude is in ATM 005. (SERA Table S5-1)

Class F and G, at and below 3 000 ft AMSL, or 1 000 ft above the terrain, whichever is the higher. The cloud distances do not apply there. Instead: stay clear of cloud, keep the surface in sight, and 5 km visibility. (Taught in LAW 005.)

Special areas

For all of these: dimensions are defined, and hours of activity are in the AIP and NOTAM.

P Prohibited areaP-area

An airspace of defined dimensions above the land areas or territorial waters of a State, within which the flight of aircraft is prohibited. Can be temporary or permanent.

Fly-through

Prohibited.

ExamplesChemical plant, military activity, etc.

R Restricted areaR-area

An airspace of defined dimensions within which flight is restricted in line with specified conditions. Not banned outright, unlike a P-area.

Fly-through

With permission from the appropriate ATS unit. Prohibited when stated in the AIP.

ExamplesBird sanctuary (e.g. during nesting season), parachute dropping zone, military activity, etc.

D Danger areaD-area

Marks an area where something dangerous to aircraft may be going on.

Fly-through

Avoid, but it’s the pilot’s responsibility. Prohibited when stated in the AIP.

ExamplesMilitary activity: bombing, firing, training sector, etc.

TRA Temporary reserved airspace

Can be in controlled or uncontrolled airspace. Reserved for one user for a set period, usually the military, and open to everyone else the rest of the time.

Fly-through

With clearance from the appropriate ATS unit. Prohibited when stated in the AIP.

ExamplesMilitary activity, military training zones, etc.

TSA Temporary Segregated Area

The same as a TRA, apart from transit: a TSA is segregated, so non-participating aircraft cannot fly through it at all.

Fly-through

Not accessible to non-participating aircraft.

ExamplesMilitary activity, military training zones, etc.

Variant of TRA and TSA

CBA Cross Border Area

A TSA or TRA that covers two or more states.

Can you fly through? R-areas and TRAs need permission, P-areas and TSAs are closed, and a D-area is left to the pilot.

Mandatory and identification zones

ADIZAir Defence Identification Zone

Requires prior notification.

Identification

TMZTransponder Mandatory Zone

Used in Class E, F and G airspace.

Transponder

RMZRadio Mandatory Zone

Used in Class E, F and G airspace.

Radio

ATS routes

Used to channel the flow of air traffic.

Airways

Controlled routes. An AWY is a control area shaped like a corridor, as above.

CDRsConditional Routes

Used for planning by pilots and aircraft operators (AOs).

RNAV routesArea Navigation

The aircraft flies its own path instead of tracking from navaid to navaid. It can do that on satellite navigation, on self-contained aids such as inertial, or on the ground-based aids themselves.

FRAFree Route Airspace

A SESAR project: fly freely between entry and exit points.

ADRsAdvisory Routes

Only in uncontrolled airspace (Class F), and only for IFR flights. A temporary measure, lasting up to 3 years, until the state decides between FIS and ATC. ATC is the fuller service of the two; ADVS sits below it.