Aeronautical Information Notice (NOTAM)

Notice to Airmen (NOTAM) is a formal type of notification issued to personnel involved in flight operations, containing critical information that may affect aviation activities. A NOTAM is an advisory publication designed to timely inform flight operations personnel about the presence, condition, or change of any aviation facility, service, procedure, or hazard. In this regard, NOTAM serves as a communication channel for temporary or urgent information that directly influences operational decision-making during flight planning and execution.^【1】

Under international civil aviation regulations, the text of a NOTAM is prepared according to a specific systematic structure and standard. NOTAMs published in accordance with the format and abbreviation system established by the International Civil Aviation Organization (ICAO) may cover changes related to navigation aids, airspace regulations, airport operations, communication services, and similar elements.

Legal and International Standard Framework

The NOTAM system is based on legal and technical standards established under international civil aviation regulations. The foundational standards are set forth in regulatory documents published by the International Civil Aviation Organization (ICAO). The format, language, numbering, location indicators, and dissemination method of NOTAMs are governed by specific rules to ensure international compatibility and operational consistency. Within this framework, Annex 15, Doc 8126, and Doc 7910 stand out as primary reference documents.^【2】

ICAO Annex 15 NOTAM Format

ICAO Annex 15 is the primary international document regulating procedures and principles for aviation information services (AIS). The preparation and issuance of NOTAMs are carried out in accordance with the systematic structure outlined in Annex 15. A NOTAM is a notification issued to flight operations personnel to timely inform them of the presence, condition, or change of any aviation facility, service, procedure, or hazard, and its format must comply with the provisions of Annex 15.

ICAO Doc 8126 System Format

ICAO Doc 8126, known as the Aeronautical Information Services Manual, is a technical document that outlines the application principles for preparing aviation information products including NOTAMs. The text of a NOTAM must include all required information in the sequence specified in the ICAO system NOTAM format.

This system format prescribes that specific data fields—such as subject, location, time, activity type, and affected area—be presented in a defined code and structure. Thus, a NOTAM becomes a structured information message rather than a free-form descriptive text, incorporating standardized codes and regulatory indicators. This structure ensures compatibility with both manual evaluation and electronic data processing systems.

ICAO Abbreviations and Code System

The text of a NOTAM consists exclusively of standardized abbreviations and phrases assigned by ICAO. These abbreviations enable the standardized expression of technical terms commonly used in aviation terminology. ICAO NOTAM codes are completed with identifiers, indicators, call signs, frequencies, numbers, and, when necessary, explicit statements.

The purpose of the code system is to ensure that messages are as brief and concise as possible while maintaining clear and unambiguous meaning. It is stipulated that NOTAMs must be as brief and concise as possible and must fully convey their purpose without reference to another document. This approach requires a balance between communication efficiency and clarity.

The use of standardized abbreviations is critical, particularly for NOTAMs subject to international distribution. For users with different native languages to interpret the same message correctly, terminology must be fixed and pre-defined. Therefore, the language of NOTAMs has a technical and coded structure distinct from everyday written language.

General Characteristics and Publication Principles

The NOTAM system is subject to specific rules not only in terms of the nature of the information it contains, but also regarding its formal structure, dissemination method, numbering system, and correction mechanisms. These rules ensure that NOTAMs operate as consistent, traceable, and reliable information products at both national and international levels. Formal standards and content principles are applied together in the preparation and issuance of NOTAMs, with error and correction processes conducted according to predefined methods.

Formal Rules

The formal structure of a NOTAM is based on a systematic numbering system using series, number, and year. Each NOTAM begins with a series code indicated by a letter that identifies its category or distribution group. The series letter is followed by a four-digit number indicating the calendar year. Numbers within the same series follow sequentially and are reset each year. This facilitates chronological tracking and archiving of NOTAMs. The year code is represented by two digits and is used after the series and number. Thus, each NOTAM is completed by a combination of series letter, four-digit sequence number, and two-digit year code.

Content Rules

Single Subject Principle

Each NOTAM must relate to only one subject and one condition of that subject. This principle prevents a single NOTAM from containing multiple independent operational changes. The aim is to avoid information confusion and ensure users can clearly identify the affected element.

Requirement for Brevity and Conciseness

NOTAMs must be as brief and concise as possible. A NOTAM must fully convey its purpose without referencing another document. Standardized ICAO abbreviations and code systems serve this purpose. The coded format prevents unnecessary length while preserving meaning within aviation terminology.

Requirement for Clear Reference

If a NOTAM cancels or modifies a previous NOTAM, it must clearly state the series and number of the canceled or modified NOTAM. Additionally, the series, location indicator, and subject of both NOTAMs must be identical. If an error is detected in a NOTAM, a new NOTAM with a new number is issued to replace the erroneous one, or the erroneous NOTAM is canceled and a new NOTAM is issued. Clarity and uniqueness are essential in this process; only one NOTAM may be canceled or replaced at a time.

AIP/SUP Reference Requirement

A NOTAM containing permanent or long-term temporary information must include a reference to the Aeronautical Information Publication (AIP) or Supplement (SUP). NOTAMs are primarily designed as tools for temporary and short-term information. Permanent or long-term changes must be incorporated into the relevant aviation information products within a specified period. After a permanent NOTAM (PERM) is issued, it must be incorporated into the relevant aviation information products within three months. A long-term temporary NOTAM must also be incorporated into the AIP SUP within three months. This practice preserves the temporary nature of NOTAMs while ensuring permanent information appears in official publications.

NOTAM Types by Content

NOTAMs are classified into different series based on their scope of issuance and content nature. This classification determines both the target audience and the subject area of the notification. Content-based series division can be grouped into three main categories: NOTAMs intended for international users, NOTAMs distributed nationally, and NOTAMs issued for areas with special status.

International NOTAM Series

International NOTAM series consist of four main series designated by the letters A, B, C, and D, as well as SNOWTAM, which is issued in a special format. These series are distributed to international users via the European AIS Database (EAD) system and are categorized according to their content.

Series A

Series A NOTAMs contain the broadest and highest-level operational information. They are issued for changes to general rules, en-route navigation and communication facilities, airspace restrictions and activities at or above FL245, information on obstacles, and details regarding airports open to international traffic.

They are particularly important for high-altitude airspace regulations and elements affecting international traffic. The issuance of airspace restrictions at or above FL245 under Series A is linked to the operational needs of IFR traffic operating at high altitudes. Changes related to airports open to international traffic are also announced under Series A.

Series B

Series B NOTAMs cover airspace restrictions and activities below FL245. Additionally, information related to IFR flights and airports open to national traffic within the Ankara and Istanbul FIRs is issued under this series.

Series B targets activities occurring in medium and low-altitude airspace and changes affecting IFR operations. Thus, unlike Series A, it provides information specific to lower airspace levels and certain national airports.

Series C

Series C NOTAMs are directed toward more limited and specialized operational areas. They include information on heliports, airports or landing areas open only to VFR flights, and civil unmanned aircraft system (UAS) flights at or above 400 ft AGL.

This series is particularly important for visual flight rules (VFR) operations and special landing areas. Additionally, civil UAS activities above specific altitude thresholds are also covered under Series C.

Series D

Series D NOTAMs are issued for information regarding military airfields. Although included in the international series, they specifically cover military airfields and associated operational changes. This series enables the notification of conditions at military facilities that may affect international flight operations.

SNOWTAM

SNOWTAM is a specialized type of NOTAM that reports the presence or removal of hazardous conditions caused by snow, slush, ice, or associated water accumulations on operational surfaces. It is published using a format distinct from the standard NOTAM format.

SNOWTAMs are numbered separately for each airport and are initiated on 1 January of each year at 00:00 UTC with the number SWLT0001. This unique numbering system reflects the critical importance of runway surface conditions for flight safety. Distribution of SNOWTAMs follows the principles specified in the relevant section of the Türkiye AIP.

National NOTAM Series (Türkiye)

National NOTAM series are published in Turkish and are intended exclusively for users within Türkiye. These series consist of four distinct groups designated by the letters G, H, L, and M. National NOTAMs are also created and distributed via the EAD system according to their content.

Series G

Series G NOTAMs cover information related to all airports in Türkiye. In addition, information on en-route and navigation facilities, airspace restrictions, and alert or warning-related changes is issued under this series. Series G has a broad national distribution scope and includes operational changes across the entire country.

Series H

Series H NOTAMs cover temporary information related to airports and navigation facilities within the Istanbul FIR. This series is geographically limited to the boundaries of the Istanbul FIR and is primarily used for announcing temporary changes.

Series L

Series L NOTAMs contain information related to unmanned aircraft systems. With the increasing number of UAS operations, a separate series was established to communicate the potential impacts of these activities on airspace users.

Series M

Series M NOTAMs cover information related to military airfields and navigation facilities of interest to military authorities. This series is numbered starting from M5001 on 1 January of each year at 00:00 UTC. Series M is distributed nationally and has a distinct numbering sequence from other series.

NOTAM Types by Function / Publication Type

NOTAMs are also classified according to their function and purpose of issuance, not only by content or distribution scope. This classification indicates whether a NOTAM contains new information, updates an existing notice, or cancels a previously issued notice. The functional classification ensures the orderly tracking of the information chain in accordance with the dynamic nature of the NOTAM system. This framework includes three primary publication types: NOTAMN (New), NOTAMR (Replace), and NOTAMC (Cancel).

NOTAMN (NOTAM NEW)

NOTAMN is an abbreviation for “New” and refers to a NOTAM issued for the first time. It is used to announce a new situation or change without any previously issued NOTAM on the same subject.

NOTAMN may be issued for situations such as the temporary closure of a runway, the unavailability of a navigation aid, the implementation of a new airspace restriction, or the emergence of an unexpected hazard. This type of NOTAM has an independent notification status and is assigned its own series and number within the system. The key characteristic of NOTAMN is that it neither modifies nor cancels any existing notice.

NOTAMR (NOTAM REPLACE)

NOTAMR is an abbreviation for “Replace” and is used when the content of a previously issued NOTAM needs to be modified. The replace operation cancels the previous NOTAM and issues a new NOTAM with updated content. When issuing a NOTAMR, the series and number of the replaced NOTAM must be clearly stated. This practice enables users to clearly identify which notice is currently valid.

The replaced NOTAM is no longer considered valid; the NOTAMR replacing it is accepted as effective. The replace method is used in cases such as extension or reduction of duration, modification of geographic area, narrowing or expanding the affected scope, or correction of errors or omissions in content. The replace concept ensures information continuity while removing incorrect or incomplete information from the system.

NOTAMC (NOTAM CANCEL)

NOTAMC is an abbreviation for “Cancel” and is used to indicate that a previously issued NOTAM has been fully revoked. The cancel operation signifies that the situation described is no longer valid and the notice has expired. For example, a NOTAMC may be issued when a temporarily closed runway is reopened or when a specific airspace restriction is lifted. The original NOTAM is considered removed from the system and loses all operational binding effect. Unlike the replace operation, the cancel operation does not introduce new content; it only announces the cancellation of an existing notice. Replace, in contrast, simultaneously cancels the previous notice and activates the updated content.

Operational Content Scope

The NOTAM system aims to timely notify of changes that may directly or indirectly affect flight safety. Therefore, the primary subjects of NOTAMs are broadly defined to encompass aviation infrastructure, services, airspace regulations, and various types of hazards.

Airport and Runway Changes

Significant changes related to airports, heliports, and runways are subject to NOTAM issuance. This includes the establishment of a new airport or runway, the closure of an existing airport or runway, the temporary decommissioning of runways, the emergence of significant hazards in maneuvering areas, and the erection, removal, or modification of obstacles affecting flight paths in runway extensions or approach areas. Such changes have operational significance as they directly impact takeoff and landing performance, alternate airport planning, and approach procedures.

ATS/CNS/MET/SAR Changes

The establishment, removal, or significant operational changes to aviation services require the issuance of a NOTAM. These services include ATS (Air Traffic Services), CNS (Communication, Navigation, and Surveillance systems), MET (Meteorological Services), and SAR (Search and Rescue Services).

Within this framework, NOTAMs must be issued when a service is interrupted or restored, when frequencies change, when service hours are modified, when call signs or identifiers are altered, when guidance aids undergo changes, when locations are moved, when power levels increase or decrease, when broadcast programs or content are modified, or when service irregularities or unreliability occur. Additionally, when backup or secondary systems become inaccessible, or when air traffic services are partially or fully interrupted, short-term contingency measures must also be announced via NOTAM.

Airspace Restrictions

Airspace regulations constitute one of the core content areas of the NOTAM system. Within this scope, temporary airspace restrictions, newly established areas, cancellation or suspension of existing areas, and level-dependent restrictions are published via NOTAM.

The creation, activation, or cancellation of prohibited, restricted, and danger areas are also included in this scope. For activities requiring temporary airspace restrictions other than emergency operations, notification must be provided at least seven days in advance.

Prohibited, Restricted, and Danger Areas

Airspace areas completely closed or restricted due to specific activities are subject to NOTAM issuance. These areas are typically established due to military operations, security reasons, or special events. The activation process, geographic boundaries, and affected flight levels of prohibited, restricted, and danger areas are clearly specified in NOTAMs.

Obstacles

The erection, removal, or modification of obstacles that may affect flight navigation requires the issuance of a NOTAM. Obstacles located in climb, approach, and overflight areas, as well as runway extensions, are of critical importance for flight safety. Additionally, the installation, removal, or reactivation of hazard lights marking these obstacles is also reported via NOTAM.

Military Exercises

Military exercises may cause temporary changes or restrictions in airspace usage. Information regarding the dates, times, and affected areas of such activities is published via NOTAM. Changes related to military airfields and military airspace are also addressed within this scope.