NOTAM and airspace terms, in plain words.

Short definitions of the 63 abbreviations and concepts you meet in European NOTAMs, pre-flight bulletins and airspace briefings, with a link to the deeper guide where one exists.

A

Activity range: On NOTAMbriefing.com, the UTC time window the map, the airspace details and your briefing show activation status for. Presets include Until midnight UTC, Until SS+15, Tomorrow and Weekend. More about Activity range
AGLAbove ground level: A height measured from the ground directly below. NOTAM items F) and G) and many obstacle notices give limits in feet or metres AGL.
AICAeronautical Information Circular: A notice with information that qualifies neither for a NOTAM nor for the AIP but relates to flight safety, air navigation, or technical, administrative or legislative matters.
AIPAeronautical Information Publication: A publication issued by or with the authority of a state, containing aeronautical information of a lasting character essential to air navigation. Airspace, aerodromes and national rules are published here.
AIP SUPAIP Supplement: Temporary changes to the information in the AIP, published on special pages. Supplements often cover exercises, events and works that last weeks or months. More about AIP SUP
AIRACAeronautical Information Regulation and Control: The system that publishes significant changes in advance on common effective dates, every 28 days. Airspace structure changes follow the AIRAC cycle; activations do not. More about AIRAC
Airspace class: A letter from A to G that fixes which flights may enter a volume of airspace, which services they receive, and whether they need an ATC clearance and radio contact. More about Airspace class
AMCAirspace Management Cell: A joint civil-military cell responsible for the day-to-day management and temporary allocation of national or sub-regional airspace. AMCs publish the AUP and UUP. More about AMC
AMSLAbove mean sea level: An altitude measured from mean sea level. With the local QNH set, the altimeter reads altitude AMSL.
ASHTAM: A special series NOTAM, in a specific format, about a change in volcanic activity, a volcanic eruption or a volcanic ash cloud that matters to aircraft operations. More about ASHTAM
ASMAirspace management: The planning function that makes the most of available airspace by dynamic time-sharing and, at times, segregation between users based on short-term needs. More about ASM
ATZAerodrome traffic zone: Airspace of defined dimensions established around an aerodrome to protect aerodrome traffic. More about ATZ
AUPAirspace Use Plan: An airspace management message of NOTAM status that notifies an AMC's daily decision on the temporary allocation of airspace, such as TRAs and TSAs, for the next day. More about AUP

C

CBACross-Border Area: An airspace restriction or reservation established over an international border for specific operational requirements. It takes the form of a TRA or a TSA. More about CBA
CDRConditional route: An ATS route, or part of one, that can be planned and used only under specified conditions. Since the single CDR category, the remaining conditional routes are called CDR1. More about CDR
Checklist (NOTAM): A NOTAM listing the valid NOTAMs of one series, normally issued monthly with the code QKKKK. A checklist never cancels a NOTAM; only a NOTAMC does. More about Checklist (NOTAM)
CTAControl area: Controlled airspace that extends upwards from a specified limit above the earth.
CTRControl zone: Controlled airspace that extends upwards from the surface of the earth to a specified upper limit, usually around an aerodrome. More about CTR

D

Danger area (D): Airspace of defined dimensions within which activities dangerous to the flight of aircraft may exist at specified times. More about Danger area (D)
DYNAMDynamic Airspace Mapping: NOTAMbriefing.com's live layer that shows whether a published airspace is active now, by combining NOTAMs, AUP/UUP data and published activation schedules. More about DYNAM

E

EADEuropean AIS Database: EUROCONTROL's central database of aeronautical information, through which European NOTAM offices publish and exchange NOTAMs and other AIS data.
EAUP / EUUPEuropean AUP / European UUP: The Network Manager's consolidation of all national AUPs and UUPs into one European plan, published on the NOP Portal and through NM B2B. More about EAUP / EUUP
ESTEstimated: Added directly after the end time in NOTAM item C) when the end time is uncertain. The NOTAM must be replaced or cancelled before that time. More about EST

F

FIRFlight information region: Airspace of defined dimensions within which flight information service and alerting service are provided. NOTAMs are filed per FIR. More about FIR
FISFlight information service: A service that gives advice and information useful for the safe and efficient conduct of flights. In class F and G airspace, flights receive it on request.
FLFlight level: A surface of constant atmospheric pressure related to the standard pressure datum of 1013.2 hPa, flown with the altimeter set to 1013. FL065 means 6 500 ft on the standard setting.
FRAFree route airspace: Airspace in which users may plan a route freely between defined entry and exit points, without reference to the ATS route network, subject to airspace availability.
FUAFlexible Use of Airspace: The European concept that treats airspace as one continuum shared in time between civil and military users, rather than as purely civil or purely military airspace. Its daily allocations are published in the AUP and UUP; DYNAM combines them with NOTAMs and published schedules. More about FUA

G

Graphical NOTAM: A NOTAM whose effect area can be drawn on a map as a polygon, circle or corridor, so pilots see where it applies instead of plotting coordinates by hand. More about Graphical NOTAM

H

H24: Continuous day and night service. In NOTAM item D), H24 means the whole day, 0000 to 2359 UTC, on the dates given.
HJ: Sunrise to sunset. Used for services and activities that operate in daylight only.
HN: Sunset to sunrise. Used for services and activities that operate at night only.
HO: Service available to meet operational requirements, rather than at fixed hours.
HX: No specific working hours. Check with the unit, or by NOTAM, whether the service or activity is available.

I

IFR / VFRInstrument flight rules / visual flight rules: The two sets of flight rules. VFR flights must stay in visual meteorological conditions (VMC); IFR flights navigate by instruments and may fly in instrument meteorological conditions, with the service the airspace class provides. More about IFR / VFR
Item D): The day and time schedule of a NOTAM, used when the notice applies only at certain periods between its start and end times. More about Item D)

N

NM B2BNetwork Manager business-to-business services: EUROCONTROL Network Manager web services through which systems exchange flight, flow and airspace data, including the European AUP and UUP. More about NM B2B
NOTAM: A notice distributed by telecommunication about the establishment, condition or change of an aeronautical facility, service, procedure or hazard that people involved in flight operations need to know about in time. More about NOTAM
NOTAM series: The letter that begins a NOTAM number, as in A0123/26. Each state allocates its series to subjects or areas and lists them in the AIP, section GEN 3.1. More about NOTAM series
NOTAMN / NOTAMR / NOTAMC: The three NOTAM types: a new NOTAM, a replacement of one earlier NOTAM, and a cancellation of one earlier NOTAM. More about NOTAMN / NOTAMR / NOTAMC

P

PERMPermanent: Used in NOTAM item C) instead of an end time when the information is permanent and will be incorporated in the AIP. More about PERM
PIBPre-flight information bulletin: A presentation of current NOTAM information of operational significance, prepared before flight for a route, an area or an aerodrome. More about PIB
Plan Ahead: Part of the NOTAMbriefing.com Live plan: airspace and NOTAM data, activation status and briefings for any day up to 45 days ahead, not just today. More about Plan Ahead
Prohibited area (P): Airspace of defined dimensions, above the land areas or territorial waters of a state, within which the flight of aircraft is prohibited.

Q

Q-codeNOTAM Code: The five-letter group in a NOTAM Q-line: Q, two letters for the subject and two for its condition, as in QMRLC for runway closed. More about Q-code
Q-lineNOTAM item Q): The qualifier line of a NOTAM: FIR, Q-code, traffic, purpose, scope, lower and upper flight levels, and a centre point with a radius, used to filter NOTAMs into bulletins. More about Q-line
QNH: The altimeter sub-scale setting that makes the altimeter read aerodrome elevation on the ground, and altitude above mean sea level in flight.

R

Restricted area (R): Airspace of defined dimensions, above the land areas or territorial waters of a state, within which the flight of aircraft is restricted in accordance with specified conditions. More about Restricted area (R)
RMZRadio mandatory zone: Airspace of defined dimensions in which carrying and operating radio equipment is mandatory. Pilots make an initial call before entry and keep a listening watch. More about RMZ

S

SERAStandardised European Rules of the Air: The common rules of the air in Regulation (EU) No 923/2012, including the airspace classes, VMC minima and RMZ/TMZ requirements. More about SERA
SNOWTAM: A special series NOTAM in a standard format that reports hazardous conditions due to snow, ice, slush, frost or standing water on an aerodrome's movement area. More about SNOWTAM
Special VFR: A VFR flight cleared by air traffic control to operate within a control zone in meteorological conditions below VMC. More about Special VFR
SR / SSSunrise / sunset: Used in NOTAM item D) schedules, sometimes with an offset, as in SR MINUS30-SS PLUS30 for 30 minutes before sunrise to 30 minutes after sunset. More about SR / SS

T

TMATerminal control area: A control area normally established at the confluence of ATS routes in the vicinity of one or more major aerodromes. Some states label similar terminal airspace TCA. More about TMA
TMZTransponder mandatory zone: Airspace of defined dimensions in which carrying and operating a pressure-altitude reporting transponder (Mode A and C, or Mode S) is mandatory. More about TMZ
TRATemporary Reserved Area: Airspace temporarily reserved for the specific use of another aviation authority, through which other traffic may be allowed to transit under ATC clearance. More about TRA
Transition altitude and level: The transition altitude is the altitude at or below which vertical position is flown by reference to altitude (QNH); the transition level is the lowest flight level available above it. Both vary between European states.
Trigger NOTAM: A NOTAM that announces an AIRAC AIP amendment or supplement. Its Q-code ends in TT and its text starts with TRIGGER NOTAM. More about Trigger NOTAM
TSATemporary Segregated Area: Airspace temporarily segregated for the exclusive use of another aviation authority, through which other traffic is not allowed to transit while it is active. More about TSA

U

UIRUpper flight information region: A flight information region covering upper airspace, where a state defines one above its FIRs. Under OPADD, the NOTAM Q-line names the FIR, never the overlying UIR. More about UIR
UTCCoordinated Universal Time: The time reference for all NOTAM, AUP and UUP times. Central European Time is UTC+1 and Central European Summer Time UTC+2. More about UTC
UUPUpdated Airspace Use Plan: An airspace management message of NOTAM status that updates and supersedes the AUP or an earlier UUP during the day. More about UUP

V

VMCVisual meteorological conditions: Visibility, distance from cloud and ceiling equal to or better than the minima for VFR flight. In the EU the minima are in SERA.5001. More about VMC

Reference guides

How to Read a NOTAM: Q-Line and Items A–G Explained

Every European NOTAM follows the same ICAO layout. Learn the header, the Q-line and items A to G once, and any NOTAM becomes a quick read.

NOTAM Q-Codes Explained: Subjects, Conditions, Examples

QMRLC, QRTCA, QWPLW: the five-letter code in every NOTAM Q-line tells you the subject and its condition before you read a word of the text.

Airspace Classes A–G in Europe: SERA Rules and VMC Minima

One letter decides whether you need a clearance, a radio call or 8 km of visibility. Here is what each class means under the Standardised European Rules of the Air.

TRA, TSA, CBA and Flexible Use of Airspace Explained

Much of Europe's military airspace is only reserved when someone needs it. The Flexible Use of Airspace concept decides when, and the AUP and UUP tell you.

TMZ and RMZ Explained: What VFR Pilots Must Do

An RMZ means you talk before you enter; a TMZ means ATC and other aircraft must be able to see you. Neither needs a clearance, and both are easy to get wrong.

Definitions follow ICAO Annex 15, Docs 8400 and 8126, the EUROCONTROL OPADD guidelines and ERNIP Part 3, and the Standardised European Rules of the Air (SERA). Always brief from the current national AIP and NOTAMs.