Weather & Decoding
Use the NOTAM decoder below to translate any raw ICAO Notice to Air Missions (NOTAM) into plain English. The decoder explains every NOTAM field, including the Q-line, Flight Information Region (FIR), NOTAM subject and condition codes, traffic, purpose, scope, validity period, D-line schedule, and E-line text, providing a complete interpretation of operational restrictions, hazards, closures, and other aeronautical information contained in the notice.
Usage Guide
The steps below explain how to use the NOTAM decoder to convert a raw ICAO Notice to Air Missions (NOTAM) into a complete plain-English field-by-field interpretation.
Copy the complete NOTAM from your flight planning application, electronic flight bag (EFB), aviation briefing service, or official Aeronautical Information Service (AIS) source. Include the entire NOTAM from the NOTAM number through to the final field to ensure all information is decoded correctly.
Paste the raw NOTAM into the input field and click Decode NOTAM. The decoder supports standard ICAO NOTAM formatting, including both single-line and multi-line NOTAM layouts. NOTAMN (new), NOTAMR (replacement), and NOTAMC (cancellation) action types are recognised and decoded automatically.
Each NOTAM field is decoded individually, including the NOTAM number, action type, Q-line components (Flight Information Region (FIR), subject and condition codes, traffic, purpose, scope, altitude limits, and coordinates), and lettered fields A through G. Hover over annotated elements to view their ICAO definitions and operational significance.
Review the E-line to identify the restriction, hazard, closure, or operational information contained in the NOTAM. Verify the validity period using the B and C fields, review the D-line if a schedule is specified, and assess the impact on your planned route, departure airport, destination airport, alternate airport, and airspace operations.
Definition
A NOTAM (Notice to Airmen) is a time-limited notice distributed through the international aeronautical information system that contains information essential to personnel concerned with flight operations. NOTAMs communicate changes to the aeronautical information environment that are temporary or short-notice in nature and cannot be published in advance through standard AIP amendments.
NOTAMs can cover a wide range of operationally relevant subjects including runway closures and restrictions, navigation aid outages and degraded service, airspace activations and restrictions, obstacle warnings, approach procedure changes, lighting outages, construction activity near movement areas, laser and parachute activity, and changes to published minima or procedures.
Each NOTAM is encoded in a standardised ICAO format consisting of a serial number, an action code (N, R, or C), a Q-line qualifier with structured fields for automated filtering, and a series of lettered fields (A through G) that define the location, validity, schedule, description, and altitude limits of the notice.
A note on the acronym: NOTAM originally stood for Notice to Airmen. On December 2, 2021, the FAA changed the term to Notice to Air Missions, describing it as more inclusive of all aviators and missions including drone operators. On February 10, 2025, the FAA changed the term back to Notice to Airmen and updated FAA Order 7930.2 accordingly. ICAO and most international authorities use Notice to Airmen or simply NOTAM. Regardless of the expanded form, the acronym NOTAM and the format remain unchanged.
NOTAM Types
NOTAMs are classified into multiple categories based on how they are issued, how they are distributed, and what operational information they contain. These classifications determine how a NOTAM is updated, how it is transmitted, and how it should be interpreted in flight planning and operational decision-making. The sections below explain the main ICAO classification system, including action types, distribution classes, special series NOTAMs, and series identifiers, followed by additional domestic classifications used by the United States FAA.
ICAO action types define whether a NOTAM is new, replaces an existing NOTAM, or cancels a previous notice. There are three ICAO action types:
A NOTAMN is a new NOTAM issued for the first time and is not linked to any previous notice. It must be read and assessed in full as an independent operational message.
A1234/23 NOTAMN — New NOTAM issued with no replacement or cancellation reference.A NOTAMR replaces a previously issued NOTAM and fully supersedes it. The replaced NOTAM number is referenced immediately after the action type, and the previous NOTAM must no longer be used for planning.
B0456/23 NOTAMR B0400/23 — Replaces NOTAM B0400/23.A NOTAMC cancels a previously issued NOTAM and removes it from operational use without replacement. The condition described in the original NOTAM is no longer active.
A1234/23 NOTAMC A1100/23 — Cancels NOTAM A1100/23.ICAO distribution classes define how a NOTAM is delivered to users and how quickly it becomes available in operational systems. There are two distribution classes:
Class I NOTAMs are distributed through telecommunications networks such as the Aeronautical Fixed Telecommunication Network (AFTN) and modern aviation data systems. They are delivered in near real time to briefing systems, electronic flight bags (EFBs), and Aeronautical Information Service (AIS) platforms. The vast majority of NOTAMs encountered in preflight planning are Class I.
Class II NOTAMs are distributed through scheduled aeronautical information publications rather than real-time systems. They are used for information known in advance and included in AIS publication cycles such as AIRAC (Aeronautical Information Regulation And Control).
Special series NOTAMs use the standard NOTAM distribution system but apply structured formats for specific operational hazards or phenomena. ICAO defines three special series NOTAMs:
A SNOWTAM reports runway surface conditions caused by snow, ice, slush, or standing water. It uses the Global Reporting Format (GRF) and RWYCC codes (0–6) to describe runway contamination by section. SNOWTAMs are time-limited and based on recent runway observations.
An ASHTAM reports volcanic ash activity that may affect aircraft operations, including location, vertical extent, and movement of ash clouds. It is issued using data from Volcanic Ash Advisory Centres (VAACs) and follows ICAO Annex 15 standards.
A BIRDTAM reports significant bird activity or migration that may create a collision risk to aircraft. It is used in some ICAO regions, but implementation and formatting are not globally standardised.
The NOTAM series identifier is the letter prefix in the NOTAM number — for example A1234/23 or J0987/24. It is an administrative classification used by individual states or FIRs to group NOTAMs by subject area such as aerodromes, en-route airspace, or military operations.
Series identifiers are not globally standardised and do not change how a NOTAM is decoded.
The United States FAA uses additional domestic NOTAM categories alongside ICAO-compliant NOTAMs. These domestic formats are being harmonised under FAA modernisation initiatives but remain operationally relevant. The FAA domestic NOTAM types are:
An FDC NOTAM contains regulatory information that carries the force of law, including instrument procedure amendments, Standard Instrument Departures (SIDs), Standard Terminal Arrival Routes (STARs), and Temporary Flight Restrictions (TFRs). Compliance is mandatory under FAA regulations.
A TFR is a restricted airspace volume issued as an FDC NOTAM. It limits or prohibits flight operations due to security, safety, or special events such as VIP movements, wildfires, or space launches. Check tfr.faa.gov before every departure.
NOTAM (D) is the most common US domestic NOTAM type and covers public-use airports, navigation aids, services, and airspace conditions.
Subtypes include: (U) Unverified NOTAMs awaiting confirmation, and (O) Other operational information not meeting standard NOTAM criteria.
A FICON NOTAM reports runway and taxiway surface conditions such as snow, ice, slush, standing water, and braking action. It uses GRF-based RWYCC codes or descriptive terms such as GOOD, MEDIUM, or POOR.
A GPS NOTAM reports degradation or outages of satellite navigation signals in a defined area and altitude range. It affects GPS-based navigation operations such as Area Navigation (RNAV), Required Navigation Performance (RNP), and Automatic Dependent Surveillance–Broadcast (ADS-B) systems.
A Pointer NOTAM directs users to another NOTAM that contains related operational information under a different identifier, reducing duplication in briefing packages.
A SAA NOTAM reports activation or changes in Special Use Airspace such as Military Operations Areas (MOAs), restricted areas, or warning areas.
A Center Area NOTAM is issued under an Air Route Traffic Control Center (ARTCC) and applies to a wide geographic area rather than a single airport. These NOTAMs often affect en-route operations across multiple airports.
Military NOTAMs are issued by military authorities within the standard NOTAM system and cover military airports, navigation aids, and airspace operations such as MOAs and restricted areas that may affect civil traffic.
Purpose
NOTAMs are used in aviation to communicate time-sensitive operational changes that affect the safety, legality, or practicality of flight operations. They provide up-to-date aeronautical information that is not yet included in published sources such as the Aeronautical Information Publication (AIP) and are a required part of flight planning and operational decision-making.
In preflight planning, NOTAMs are checked for the departure airport, destination airport, alternate airports, and any airspace along the planned route. A NOTAM may indicate runway closures, navigation aid outages (such as ILS or VOR failures), airspace restrictions, obstacle hazards, or procedural changes that directly affect route planning, approach availability, and operational minima.
Flight operations personnel, including dispatchers and airline operations centers, use NOTAMs for route optimisation, fuel planning, and regulatory compliance. Under ICAO and FAA requirements, NOTAM review is a mandatory part of IFR preflight briefing, and certain NOTAMs — particularly those involving instrument procedures, airspace restrictions, or Temporary Flight Restrictions (TFRs) — carry direct regulatory and operational consequences for flight legality.
Under 14 CFR §91.103, the pilot in command must, before beginning a flight, become familiar with all available information concerning that flight. NOTAMs are explicitly included within this required preflight information.
Failure to review NOTAMs before departure can result in regulatory enforcement action, particularly if the flight operates into conditions affected by a published Temporary Flight Restriction (TFR), runway closure, or other active NOTAM. Such violations may lead to certificate action by the FAA.
In enforcement precedent, the National Transportation Safety Board (NTSB) has found pilot error where a pilot operating with significant experience failed to review NOTAMs and landed on a closed runway, resulting in an accident and aircraft damage. The pilot’s experience level did not mitigate responsibility.
Under ICAO Annex 2, the pilot in command is responsible for the safe operation of the flight and is required to be familiar with all available aeronautical information relevant to the intended flight, including NOTAMs, prior to departure.
This requirement is implemented through national aviation regulations in all ICAO member states, meaning that preflight NOTAM review is a universal operational obligation, even though the legal wording may vary by jurisdiction.
Origin
NOTAM data originates from aerodrome operators, air navigation service providers, national civil aviation authorities, and military authorities who report operational changes affecting aviation safety and procedures.
NOTAMs exist because permanent aeronautical information is updated on a fixed 28-day AIRAC (Aeronautical Information Regulation And Control) cycle. Changes that occur outside this cycle — such as runway closures, navigation aid outages, temporary airspace restrictions, or obstacle hazards — are reported through NOTAMs to ensure immediate distribution of time-sensitive operational information.
Each originating authority submits NOTAM data to its national Aeronautical Information Service (AIS), where it is validated, encoded in ICAO standard format, and distributed through international aviation data networks.
In the United States, NOTAMs are processed and distributed through the FAA NOTAM System. Internationally, NOTAM distribution is managed through the ICAO Aeronautical Fixed Telecommunication Network (AFTN) and modern digital aviation data exchange systems. NOTAMs are then made available through official AIS portals, flight planning systems, electronic flight bags (EFBs), and aeronautical information services.
Modern NOTAM distribution is transitioning toward ICAO Digital NOTAM standards, which use structured data formats (including XML-based encoding) to improve machine readability, filtering, and automated processing compared to traditional free-text NOTAM formats.
Official NOTAM sources vary by state but are published through national Aeronautical Information Services (AIS):
notams.faa.gov)Third-party platforms such as flight planning applications and electronic flight bags may visualise NOTAMs, but the official AIS publication remains the authoritative source in most jurisdictions. Pilots should always perform a final NOTAM check immediately before departure using the official system.
Infrastructure
NOTAM infrastructure is critical to global aviation safety because it delivers time-sensitive operational information, and system failures can directly disrupt national and international air traffic.
In January 2023, a database corruption during routine FAA maintenance caused a failure of the US NOTAM system, resulting in a nationwide ground stop that paused all domestic departures — the first since September 11, 2001. More than 11,000 flights were delayed or cancelled. The FAA later determined that a contractor had unintentionally deleted files during a system synchronisation and that backup redundancy did not activate correctly.
The incident exposed the operational dependence of modern aviation on NOTAM distribution systems and led to legislative and technical responses, including the NOTAM Improvement Act of 2023 (H.R. 346) and the development of the FAA Notice to Airmen Modernization Service (NMS), which reached initial operational capability in September 2025.
Context
NOTAMs are difficult to read because they use compressed legacy encoding, dense abbreviations, structured code fields, and high information volume that are not immediately human-readable without decoding knowledge.
The six factors below explain the specific challenges that make raw NOTAM interpretation difficult without systematic decoding:
NOTAMs use dense ICAO abbreviations defined in ICAO Doc 8400 — terms like CLSD, U/S, BTN, WI, UFN, and HJ require either memorisation or a reference table to interpret accurately. A single E-line may contain a dozen abbreviations, each with a precise operational meaning.
The Q-line packs eight distinct fields — FIR, subject code, condition code, traffic, purpose, scope, altitude limits, and coordinates — into a single forward-slash-separated string that is not human-readable at a glance. Correctly interpreting QMRLC or QIGCO requires knowing the full subject and condition code system.
Start and end times use the YYMMDDHHmm format without separators — for example, 2301270600 must be parsed as 0600 UTC on 27 January 2023. Errors in time interpretation are one of the most common causes of NOTAM misapplication, particularly when converting between local time and UTC.
A typical long-haul IFR briefing may contain 100 to 300 or more individual NOTAMs across departure, enroute FIRs, destination, and alternates. Reading each one individually and correctly assessing its operational impact is a significant workload task that scales with route complexity.
The majority of NOTAMs in any given briefing have no operational impact on a specific flight — administrative notices, lighting inspections, and procedure changes that do not affect the planned route. Identifying the operationally critical NOTAMs from among hundreds of non-relevant notices requires both experience and a systematic triage approach.
A raw NOTAM provides coordinates and a radius but no map. Assessing whether a restricted area or obstacle affects a planned departure or arrival path requires mentally translating geographic coordinates into a spatial picture — a non-trivial task, particularly for pilot students and for operations at unfamiliar airports.
In July 2017, Air Canada Flight 759 came within 100 feet of landing on a taxiway at San Francisco International Airport with four other aircraft on it. The adjacent runway was closed, but the closure NOTAM was buried in a dense briefing package in a format that made it easy to miss. The National Transportation Safety Board investigation concluded that the NOTAM system as designed was so difficult to use that operationally critical information was routinely overlooked. NTSB chairman Robert Sumwalt described NOTAMs as “a bunch of garbage that nobody pays any attention to.” The incident directly triggered ICAO’s initiative to reform the NOTAM system and was a primary driver of the FAA’s subsequent NOTAM Improvement Act of 2023 and the move to structured Digital NOTAM format.
Validity
NOTAM validity and expiry refer to the time period during which a NOTAM is operationally active, how its start and end times are defined, and how it is updated, replaced, or cancelled during its lifecycle. Proper interpretation of validity information is essential to determine whether a NOTAM applies to a planned operation at a given time.
The sections below explain the validity structure, scheduling logic, and update mechanisms used in NOTAMs.
Every NOTAM includes a start time (B-field) and an end time (C-field), expressed in UTC using the format YYMMDDHHmm. The NOTAM is only operationally active within this time window.
A C) PERM entry indicates a permanent change to aeronautical information, while C) EST indicates that the end time is estimated and may be extended. In such cases, pilots must monitor for subsequent amendments or replacements.
The optional D-line defines specific time periods within the B–C validity window during which the NOTAM is active.
Only the periods specified in the D-line are affected by the NOTAM. For example, a schedule of D) 0600-1400 MON-FRI means the restriction applies only during those hours on weekdays and does not apply outside the stated times.
The D-line must always be checked to determine whether a NOTAM is operationally relevant to the planned flight time.
NOTAMs are updated through replacement or cancellation using NOTAMR (replace) and NOTAMC (cancel) action types.
A NOTAMR supersedes a previous NOTAM and replaces it entirely, while a NOTAMC cancels the original NOTAM without replacement. When either is issued for a NOTAM included in a briefing, the original NOTAM is no longer valid and must not be used for operational planning.
Comparison
A NOTAM is a general-purpose aviation notice used to distribute any time-sensitive operational aeronautical information, while a SNOWTAM is a specialised type of NOTAM used exclusively to report runway surface conditions caused by snow, ice, slush, or standing water at an aerodrome.
A SNOWTAM is a subtype of NOTAM, meaning all SNOWTAMs are NOTAMs, but not all NOTAMs are SNOWTAMs.
The table below summarises the key operational differences between NOTAM and SNOWTAM.
NOTAMs cover a wide range of operational subjects including runway closures, navigation aid outages (such as ILS or VOR), airspace restrictions, obstacle hazards, and procedure changes. SNOWTAMs are limited exclusively to runway surface contamination reporting and use the Global Reporting Format (GRF) to standardise friction and contamination assessment.
Both NOTAMs and SNOWTAMs are distributed through the same ICAO NOTAM network and accessed via the same flight briefing systems, electronic flight bags (EFBs), and Aeronautical Information Service (AIS) portals.
Decoding Guide
A NOTAM is read from top to bottom, starting with the NOTAM identifier and action type, followed by the structured Q-line metadata fields, and ending with the lettered operational description fields (A–G) that define location, timing, and detailed restrictions.
The breakdown below follows the standard ICAO NOTAM structure in reading order.
The NOTAM number uniquely identifies the notice in the format Annnn/YY, where A is the series letter assigned by the issuing authority, nnnn is a sequential four-digit number, and YY is the two-digit year of issuance. For example, A1234/23 is NOTAM number 1234 issued in 2023 in the A series. The NOTAM number is used for tracking, replacement, or cancellation — NOTAMR and NOTAMC will reference this number when superseding or withdrawing a notice.
The action code defines the NOTAM lifecycle state:
NOTAMN — new NOTAMNOTAMR — replaces an existing NOTAM (reference number included)NOTAMC — cancels a previous NOTAM (reference number included)This field determines whether the NOTAM introduces new information or modifies an existing notice.
The FIR identifies the airspace region responsible for the NOTAM (e.g. EGTT = London FIR). This determines the controlling authority and geographic scope of distribution.
The NOTAM code is a five-letter ICAO code starting with “Q”:
Example: QMRLC = runway closed.
These fields define who the NOTAM applies to and how it should be used:
Defines vertical and geographic applicability:
Lists ICAO identifiers of the aerodromes or locations affected by the NOTAM.
Defines when the NOTAM becomes active using UTC in YYMMDDHHmm format. The NOTAM is not valid before this time.
Defines when the NOTAM ends:
PERM — permanent changeEST — estimated end time (subject to extension)This field determines operational validity for flight planning.
Defines specific time windows within the B–C period when the NOTAM applies. If no D-line is present, the NOTAM is continuous throughout the validity period.
The E-line contains the full operational description using ICAO abbreviations. This is the most operationally important field and defines the actual restriction, hazard, or condition in plain-coded format.
Define vertical limits for airspace or obstacle-related NOTAMs:
SFC = surfaceUNL = unlimitedHere is a NOTAM example:
A1234/23 NOTAMN
Q) EGTT/QMRLC/IV/NBO/A/000/999/5130N00028W005
A) EGLL B) 2301270600 C) 2301270900
E) RWY 09L/27R CLSD FOR SNOW CLEARING OPS. ALTERNATIVE RWY 23L/05R AVBL.
Here is how to read the NOTAM, field by field:
A1234/23
NOTAM number 1234 issued in 2023. The A prefix indicates the aerodrome series used in this FIR. The serial number is used to track, replace, or cancel the NOTAM.
NOTAMN
This is a new NOTAM — no previous notice is superseded. NOTAMR would reference a replaced NOTAM number; NOTAMC would reference a cancelled one without new conditions.
Q) EGTT/QMRLC/IV/NBO/A/000/999/5130N00028W005
A) EGLL
EGLL is London Heathrow Airport. This NOTAM applies specifically to EGLL.
B) 2301270600 C) 2301270900
B = 2301270600: year 23, month 01, day 27, 0600 UTC. C = 2301270900: 0900 UTC same day. Active for a 3-hour window. Any planned arrival between 0600 and 0900 UTC must account for this runway closure.
E) RWY 09L/27R CLSD FOR SNOW CLEARING OPS. ALTERNATIVE RWY 23L/05R AVBL.
Runway 09L/27R is closed for snow clearing. Alternative runway 23L/05R is available. This is the operationally critical field — it confirms which runways are affected and what alternatives exist. Always read the E-line in full.
The United States has historically used a domestic NOTAM format that differs significantly from the ICAO standard. The domestic format is more concise but less structured, designed for human readers rather than automated systems. The FAA is transitioning to full ICAO format compliance; during the transition, both formats may appear in US briefing materials.
Here is the same runway closure at Chicago O'Hare expressed in both formats:
!ORD 06/001 ORD RWY 04L/22R CLSD 2106231700-2106232300
B0667/21 NOTAMN
Q) KZAU/QMRLC/IV/NBO/A/000/999/4159N08754W005
A) KORD B) 2106231700 C) 2106232300
E) RWY 04L/22R CLSD
The ICAO format is more verbose but fully structured and machine-readable. The FAA's Notice to Airmen Modernization Service (NMS) completed its first phase in September 2025, moving the US system toward full ICAO format compliance. Canada completed its own transition from domestic to ICAO format in 2019.
Q-Code Reference
The NOTAM Q-code is a five-letter ICAO code used to identify the subject and condition of a NOTAM for automated filtering, classification, and briefing system processing. Understanding the Q-code allows pilots and dispatchers to quickly determine what a NOTAM concerns before reading the full E-line description.
The annotated example and reference table below explain how the Q-code is structured and decoded:
The second and third letters of a NOTAM Q-code identify the subject. The tables below cover all ICAO-defined subject categories.
The fourth and fifth letters of a NOTAM Q-code describe the status or condition of the subject. The tables below cover all ICAO-defined condition categories.
Reference
The examples below show complete real-world NOTAM strings broken down field by field, with each element decoded and explained in plain language.
B0456/23 NOTAMR B0400/23
Q) KJZZ/QILCO/IV/BO/A/000/999/4038N07346W005
A) KJFK B) 2302010000 C) 2302282359
D) 0600-2200
E) ILS RWY 04L GLIDEPATH UNSERVICEABLE. LOC ONLY APPROACH AUTHORISED. CAT I MINIMA APPLY.
C0789/23 NOTAMN
Q) YMMM/QOBCE/IV/NBO/AE/000/005/3352S15112E001
A) YSSY B) 2306010000 C) 2309302359
F) SFC G) 500FT AMSL
E) CRANE ERECTED 750M NE THR 34L. HEIGHT 350FT AGL. OBST LGT INSTALLED.
Format Evolution
The ICAO Digital NOTAM format is a structured, XML-based NOTAM standard that replaces the traditional free-text NOTAM format to enable machine-readable distribution and automated processing of aeronautical information. Mandatory transition to this format was required from November 2023 under ICAO Annex 15, marking a significant shift in how aeronautical notices are encoded and distributed globally.
The traditional ICAO NOTAM format encoded most operational information in free-text form within the E-line, which required manual interpretation.
The ICAO Digital NOTAM format replaces this with structured XML-based data fields, allowing automated systems to parse, filter, and display NOTAM information more consistently and accurately across digital aviation platforms. Mandatory implementation was required from November 2023 under ICAO Annex 15.
For end users such as pilots, dispatchers, and air traffic personnel, Digital NOTAMs are typically converted by electronic flight bags (EFBs) and briefing systems into a human-readable format that closely resembles the traditional NOTAM layout.
The core ICAO NOTAM structure remains unchanged. Both traditional and Digital NOTAM formats include:
The underlying operational meaning and decoding process remain consistent across both formats.
The E-line description must always be read in full regardless of whether the NOTAM is displayed in traditional or Digital format, as it contains the operationally relevant information required for flight planning and safety assessment.
Operational Knowledge
Using NOTAMs for preflight briefing means identifying which notices affect the safety, legality, and feasibility of a planned flight, and determining how those notices impact routes, procedures, airports, navigation aids, and operational minima.
The best-practice guidelines below highlight common NOTAM review errors and the situations where NOTAMs have the greatest operational impact.
The D-line determines when a NOTAM is active within its overall validity period. A runway closure with D) 0600-1400 MON-FRI does not apply on weekends or outside those hours. Always verify that the D-line overlaps your planned operations window before concluding that a NOTAM affects your flight.
An ILS NOTAM can change the legal minima for an instrument approach. For example, a glidepath outage may downgrade an ILS approach to a localiser-only approach, resulting in higher minimums. Always review the applicable approach chart and determine whether revised minima affect destination or alternate planning.
A NOTAMR (replace) or NOTAMC (cancel) immediately changes the validity of a previous NOTAM. Before relying on any NOTAM, confirm that it has not been superseded, replaced, or cancelled by a newer notice.
The E-line contains the operational details of the NOTAM and must always be read in full. The Q-code identifies the subject and condition category, but only the E-line explains the specific restriction, outage, exception, location, or operational impact.
A Pre-Flight Information Bulletin (PIB) consolidates NOTAMs relevant to a specific flight, including departure, destination, alternate airports, and en-route airspace. A fresh PIB should always be obtained close to departure because new NOTAMs may have been issued since the previous briefing.
A Q-code containing XX indicates that the subject does not fit a standard ICAO NOTAM code. In these cases, the E-line is the only source of operational information and must be reviewed carefully.
Some NOTAMs act as trigger NOTAMs and direct users to a more detailed document, such as an AIP Supplement or Aeronautical Information Circular (AIC). When a NOTAM references another document, the referenced publication must also be reviewed before assessing operational impact.
Navigation aid outages may affect route planning, instrument procedures, or alternate airport suitability even when they are not associated with a departure or destination airport. Route-wide NAVAID NOTAMs should be reviewed as part of every IFR briefing.
For ETOPS operations, NOTAMs affecting designated en-route alternates can invalidate alternate suitability. Runway closures, navigation aid outages, reduced airport services, or changes to available approach procedures may require alternate selection changes or route revisions before dispatch.
Common Pitfalls
The most common NOTAM planning mistakes are misinterpreting validity times, skipping the E-line description, misunderstanding the area of effect, overlooking trigger NOTAMs, and relying on outdated briefings. Any of these errors can result in an incorrect assessment of a NOTAM’s operational impact and may affect flight safety, legality, or feasibility.
The examples below explain each mistake and how to avoid it.
All NOTAM times are published in UTC. Comparing a NOTAM validity period against local departure or arrival times without converting to UTC can result in a NOTAM being incorrectly assessed as active or inactive.
The Q-code identifies the category of a NOTAM, but the E-line contains the operational details. Assessing a NOTAM from the Q-code alone can result in critical information being missed, including affected runways, restrictions, schedules, exceptions, or operating conditions.
The Q-line contains geographic coordinates and a radius that define the area affected by a NOTAM. Assuming a NOTAM is irrelevant because the aerodrome or airspace identifier is unfamiliar can result in nearby restrictions or hazards being overlooked.
A trigger NOTAM exists to direct users to a separate document, such as an AIP Supplement or Aeronautical Information Circular (AIC), that contains the full operational details. Ignoring the referenced document means the NOTAM has not been fully assessed.
A NOTAM briefing is only accurate at the time it is generated. New NOTAMs may be issued, existing NOTAMs may be replaced, or active NOTAMs may be cancelled after the briefing is obtained.
Common Questions
A NOTAM communicates time-sensitive operational information such as runway closures, navigation aid outages, airspace restrictions, and procedure changes, while a SIGMET communicates significant meteorological hazards affecting aircraft in flight, such as severe turbulence, severe icing, volcanic ash, tropical cyclones, and widespread dust or sandstorms. NOTAMs are issued through the aeronautical information system under ICAO Annex 15. SIGMETs are issued by Meteorological Watch Offices (MWOs) under ICAO Annex 3. Both must be reviewed as part of a complete preflight briefing because operational and weather hazards are reported through separate systems.
Yes. NOTAM review is required for both VFR and IFR flights because pilots must become familiar with all available information relevant to the flight before departure. Under 14 CFR §91.103, this obligation applies to all flights in the United States. ICAO member states impose equivalent requirements through their national regulations. NOTAMs affecting VFR operations commonly include Temporary Flight Restrictions (TFRs), airspace restrictions, parachute activity, laser activity, obstacle notices, and aerodrome closures.
Yes. An active NOTAM at the destination does not automatically prevent departure; its operational impact must be assessed against the planned arrival time and the type of operation being conducted. For example, a runway closure that ends before arrival may have no impact, while an active aerodrome closure during the arrival window may require a delay, diversion, or alternative destination. The validity period, D-line schedule, and operational details in the E-line should always be compared against the planned arrival time before making a dispatch decision.
UFN means Until Further Notice and indicates that no specific end date or time has been established for the NOTAM condition. A NOTAM containing UFN remains active until it is cancelled or replaced by a subsequent NOTAM. UFN is commonly used for long-term construction projects, equipment outages awaiting repair, and temporary operational changes that do not yet have a confirmed completion date.
A NOTAM publishes temporary or short-notice operational information, while the AIP (Aeronautical Information Publication) contains permanent aeronautical information and operational procedures. The AIP is updated through the AIRAC cycle and serves as the authoritative reference for aerodrome, airspace, navigation, and procedural information. NOTAMs are used when information must be distributed immediately and cannot wait for the next AIRAC update. Permanent changes initially published by NOTAM are normally incorporated into the AIP at a later date.
A NOTAM can be issued days, weeks, or even months before it becomes active, provided the event or condition is known in advance. Common examples include scheduled runway maintenance, construction projects, air displays, and temporary airspace restrictions. A NOTAM becomes operationally active at the start time specified in the B-field, regardless of when it was issued. Receiving a NOTAM before its start time does not mean the restriction is currently in effect.
ICAO Doc 8400 — ICAO Abbreviations and Codes is the official reference document that defines the abbreviations used in NOTAMs. The document standardises abbreviations used throughout international aviation communications, including NOTAMs, METARs, TAFs, and aeronautical publications. Examples include CLSD (closed), U/S (unserviceable), BTN (between), WI (within), RWY (runway), TWY (taxiway), THR (threshold), and UFN (until further notice).
Some UAV and drone operations require a NOTAM, depending on the country, airspace, altitude, and type of operation being conducted. NOTAM requirements commonly apply to Beyond Visual Line of Sight (BVLOS) operations, operations in controlled airspace, large-scale drone activities, and other operations specified by national aviation authorities. When drone activity is published by NOTAM, pilots should assess the location, altitude limits, and operating times against their planned route and altitude to determine operational impact.
A NOTAM communicates time-sensitive operational information in a concise format, while an AIP Supplement (AIP SUP) publishes temporary operational information that is too detailed, extensive, or long-term to be conveyed effectively in a NOTAM. NOTAMs typically describe a specific restriction, outage, or operational change using a short coded message. AIP Supplements often include charts, diagrams, procedures, schedules, and detailed operational instructions. When a temporary change requires extensive supporting information, a trigger NOTAM is usually issued directing pilots to the relevant AIP Supplement.
A NOTAM distributes temporary or short-notice operational information immediately, while an AIRAC update publishes planned permanent or long-term aeronautical information on a scheduled 28-day cycle. NOTAMs are used for events such as runway closures, navigation aid outages, temporary airspace restrictions, and construction activity that cannot wait for the next publication cycle. AIRAC updates are used to publish permanent changes to aerodromes, airspace structures, instrument procedures, navigation aids, and charts. Information initially distributed by NOTAM may later be incorporated into an AIRAC publication if the change becomes permanent.
A NOTAM communicates operational information that may remain valid for hours, days, weeks, or months, while an ATIS (Automatic Terminal Information Service) provides a continuously updated broadcast of current aerodrome information and weather conditions. NOTAMs are part of the aeronautical information system and cover subjects such as runway closures, navigation aid outages, lighting failures, and airspace restrictions. ATIS broadcasts typically include the current runway in use, active instrument approaches, weather observations, altimeter setting, and other operational information relevant to arriving and departing aircraft. Pilots should review NOTAMs during preflight planning and obtain the current ATIS before arrival or departure.
A Temporary Flight Restriction (TFR) is a specific type of airspace restriction, while a NOTAM is the communication system used to distribute aeronautical information. In the United States, TFRs are typically issued as FDC NOTAMs and temporarily restrict aircraft operations within a defined area for reasons such as VIP movements, disaster response, security events, airshows, or space operations. Every TFR is communicated through a NOTAM, but most NOTAMs are not TFRs. Pilots must review NOTAMs to identify any TFRs that may affect their planned route of flight.