Digital NOTAM (Phase 3 P-21)

The aim of the Digital NOTAM project is to provide the standards, the framework, resources and a substantiated proof-of-concept for the full ECAC-wide implementation of the digital NOTAM concept, necessary to all ATM actors in order to support an accurate and always up-to-date common situational awareness of the aeronautical operations environment.

The digital NOTAM concept is an investment in the future, but with immediate practical benefits for the end users. It will bring new value to investments made in recent years, e.g. European AIS database, which delivers static data in digital format. It is a project with finalisation in the AIM domain when it comes to pre-flight briefing. Digital NOTAM can accommodate legacy system and improve the quality of the information provided to legacy NOTAM users.

Definition of traditional NOTAM: "NOTAM - A notice distributed by means of telecommunication containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to personnel concerned with flight operations."

Today, temporary information in the NOTAM system is provided mainly as free text and it is loosely structured. This is incompatible with the increasingly automated aeronautical information management systems, which largely rely on timely, accurate and quality assured aeronautical data. Some of the drawbacks of the current NOTAM system are further discussed on this webpage.

Definition of Digital NOTAM: "Digital Aeronautical Information Update (Digital NOTAM) - a data setmade available through digital services containing information concerning the establishment, condition or change in any aeronautical facility, service, procedure or hazard, the timely knowledge of which is essential to systems and automated equipment used by personnel concerned with flight operations."

The Digital NOTAM encoding is based on the Aeronautical Information Exchange Model (AIXM) version 5, which has been developed in cooperation between EUROCONTROL and the United States Federal Aviation Administration (FAA), with the support of the international AIS community.

Read more about the digital NOTAM concept and its expected benefits in the Digital NOTAM brochure Digital NOTAM BrochureDigital NOTAM Brochure.

Stakeholder consultation

Digital NOTAM and the AIXM 5 development have been constantly presented to and supported by the members of the AI Team of EUROCONTROL and by participants in a broad spectrum on other fora including dedicated workshops and a Digital NOTAM Event Specification Focus Group.

From 2007 to 2010 a total of 6 Digital NOTAM Workshops were organised at EUROCONTROL HQ in Brussels. Attendance going from 50 persons at the first workshop to over 130 participants, with overwhelming support for the project every time. More information on these workshops is availble on OneSky Teams. One of the most important documents resulting from these consultations, and especially from the FG, is the Digital NOTAM Event Specification - Increment 1 (pdf).

Traditional NOTAM

Currently, last minute aeronautical information update means “NOTAM”. Created 60 years ago, it is based on text messages, which are intended to convey to pilots and other “airman” information that is critical for the safety of the flight. Yet today the NOTAM system is increasingly used for information that is not safety critical, but which could affect the efficiency of the flight.

It is clear that the current NOTAM messages and similar text messages, containing safety critical information, cannot satisfy the future ATM system. The NOTAM system is constrained by a number of aspects that are related to its history, as visible in the NOTAM samples included beside.

Human Interpretation required

The ATM system is increasingly relying on automated systems at all levels, which depend on correct and up-to-date information in order to perform their functions. However, the content of a database, be it on-board, at the airport or in an ATC system, may be ‘superseded by NOTAM’. The task of remembering which information is overridden becomes the pilot’s or controller’s burden. There is a risk that safety critical, last minute information remains outside the automated data processing chains and in consequence missed by some or all the actors involved.

The current system is driven by manual processes to ensure NOTAM accuracy and provide a way for humans to correct NOTAM entry errors. The system relies heavily on post-submission quality control.

Although supposed to be human readable, there are frequent complains from pilots, especially from general aviation, that NOTAM text is frequently hard if not impossible to decipher for the non-expert. The recent Airspace Infringement Workshop held in EUROCONTROL refers.

The current concept of issuing safety critical information as free text is also inefficient, as it requires human reading and interpretation before being fed into the automated systems. It’s the same piece of text that is read by many recipients, who all do the same: read it, interpret it and input it in the database. This can significantly slow down the information flow. It can also trigger misunderstandings, as shown by frequent discussions on AIS Agora (the on-line forum for AIS professionals), that ask for clarification with regard to the exact meaning of the words used in NOTAM.

Information overload

Information is becoming more dynamic and the number of NOTAM published is increasing. According to statistical information 2000 and 2006 from the European AIS Database (EAD), the number of NOTAM issued have increased by 70% in Europe and by 65% world-wide, as presented in the table at the right.

Today 20,000 NOTAM (on average) are currently in force world-wide. Many of these are given to flight crews for pre-flight briefing resulting in Pre-flight Information Bulletin (PIB) in the range of 10-50 pages for an internal European flight.

Due to the current limited information filtering capabilities of the text NOTAM format, between 40% and sometimes up to 90% of the information given in PIB has no direct impact on the flight for which it was provided giving rise to the statement:

"...most information given in flight paperwork is user hostile.",
Captain “Rocky” Stone, Chief Technical Pilot, United Airlines, AIM Congress 2007

Yet the probability of pilots not being aware of important and pertinent NOTAM is increasing. Due to the complexity of airspace, databases, and publishing errors, there is a tendency to use the NOTAM system as a correctional medium overwhelming the users with data which actually degrades safety.

Geographical and temporal inaccuracies

By its nature, aeronautical information is geographically related and even of geometrical expression (airport surfaces, routes, airspace, etc.). The part of the NOTAM message that can today be interpreted automatically is limited to “position and radius of influence”. This seriously undermines the efforts to present the NOTAM information graphically.

Knowing the information filtering limitations and to be on the safe side, the NOTAM originators tend to overestimate the radius of influence, which causes the NOTAM to be included in briefings for flights that are totally outside the really impacted area.

NOTAM can also contain applicability schedules such as TSA active “APR 14 1200-1250 1300-1350 2000-2050, 15 1200-1250 2000-2150, 16 0800-0850 0900-0950 1200-1250…”. Hard to read and sometimes even ambiguous, such schedules require human reading skills which are not within the capabilities of automated systems. Even more, the temporal information is not always presented in the NOTAM D field. Sometimes, supplementary applicability information is provided in the free text description, which makes the interpretation even more difficult.

Way forward

Future ATM relies on advanced data exchange and data sharing services that communicate aeronautical information (infrastructure, route network, aerodrome, terrain, weather, obstacle data…) into the operational activities on the ground and in the air. As a prerequisite, all information has to be digital, which means suitable for automatic processing without human intervention.

In the case of NOTAM and similar messages (SNOWTAM, ASHTAM, etc.), this requires a specific approach, along two main lines of action:

- Data modelling - extend the existing data models for static aeronautical information with the necessary concepts and attributes in order to also model its dynamic/temporary evolution;

- Concept of Operations - develop technical and operational specifications that enable the development and implementation of systems and procedures, which are required for the origination, provision and use of the last minute aeronautical information updates. In particular, the concept of operations shall be applicable world-wide. It should also be backwards compatible, able to support legacy users with classical NOTAM for as long as necessary. Users of the new concept shall be able to get a rapid benefit.

What is ''digital NOTAM"?

A digital NOTAM can be defined as a data set that contains in a structured format, which can be fully interpreted by an automated system without human interpretation, the information currently distributed by text NOTAM messages.

Digital NOTAM is not a simple conversion of the current message into a new, more structured format. It is a radical change, by which the information updates (both temporary and permanent) are merged with the information of longer duration, using the same data structures and distribution channels.

The focus is on correct, complete and up-to-date data and not on a particular message product. Similar to the other products of an AIS, such as AIP, charts, etc. and for as long as necessary, the current NOTAM messages will continue to be issued. But, this will be based on the conversion of the digital aeronautical data, which will become the reference.
Although originally applied to aeronautical information, the concept is also applicable to meteorological information, for messages such as Terminal Area Forecast (TAF), etc.

The characteristics of a digital NOTAM include:

  • Geo-referenced - the information can be automatically plotted on a chart;
  • Temporal - the effective time can be computer interpreted;
  • Linked to static data - the change is cross-referenced to the baseline information;
  • Transformable – the information can be converted into any graphical or textual output, including the existing ICAO NOTAM format;
  • Query Enabled - a computer system can use complex queries to select temporary and last minute updates of interest based on user-specified criteria;
  • Electronically distributable - the information can be directly transmitted and incorporated into other computer systems without manual intervention


SESAR - the common picture 

Digital NOTAM contributes to the Information Management Strategy goal of creating a community of pe ople, devices, information and services interconnected by a communications network to achieve optimal benefit of resources and better synchronization of events and their consequences. This is also known as a 'net-centric' or 'information-centric' system.

This will enable the machines that assist the human actors to provide a common and accurate view of the aeronautical 4D environment, which is central to SESAR. It will support 4D trajectories, common decision making processes and the required safety, efficiency and capacity gains.

Safety, efficiency, capacity

Awareness systems - there are examples of incidents and accidents, which demonstrate that xNOTAM could enable computers to do a much better job in preventing the pilots and air traffic controllers from actions with potentially dangerous consequences. Electronic Flight Bag (EFB) systems are implemented by aircraft manufacturers and by many airlines as a way to better support the pilot with the right information in each particular instance. Digital NOTAM can bring into such systems the actual situation, e.g. closed runways and taxiways, work in progress areas, temporary routes, etc. AIS/MET data link standards are being developed for this goal by EUROCAE/RTCA.

Better pre-flight briefing - with digital information it is possible to structure the Pre-Flight Information Bulletin (PIB) by applying human factor principles that maximise the transfer information in the working memory of the pilot, e.g. group by feature affected; order by the criticality of the information; use images and a structure that facilitate the reading and give more visibility to the pilot to identify a situation affecting the flight

Consistent quality - with digital information, it is possible to put in place exhaustive and cost-efficient data validation and evaluation procedures, e.g. the unavailability of a critical navaid could immediately trigger the unavailability of a certain approach procedure. Obviously, this requires proper change impact procedures to be defined and encoded in the system. But this is a once-only effort, which enables an automatic process to take place in all similar situations.

Increased efficiency - through Digital NOTAM, the information is encoded only once, at the point of origin. At the end user side, Digital NOTAM will enable radical improvement in the information filtering capabilities. This will stop the information overload and the time spent on analysing irrelevant information.

Increased capacity - aeronautical information cannot directly increase capacity. However, poor information quality (in its broadest sense) often results in the extension of protection volumes and surfaces, with the consequent loss of capacity. Digital NOTAM is a pre-requisite for the construction and timely maintenance of the information pool necessary to support the capacity increase foreseen by concepts such as 4D trajectories, time based separation, reduced RNP, etc. and especially common decision making (CDM).

Airspace users benefits

Two radical improvements that are requested by all airspace users will be directly delivered by the Digital NOTAM project: graphical visualisation instead of simple text; and improved information filtering capabilities. This will enable the airspace users to exploit routing possibilities that today remain hidden, because it is practically impossible to manually process the incoming text messages in order to identify the real useful information.

Read the Digital NOTAM Preliminary Business Case


Digital NOTAM Trial

A large scale Digital NOTAM Trial has been organised by EUROCONTROL from 2008 onwards to validate the AIXM capability to provide digital NOTAM.

The initial part of the Trial already demonstrated that the AIXM 5.0 model is sufficiently mature to support the Digital NOTAM concept. The Trial also identified some modelling deficiencies, which were corrected. The result of the AIXM 5.0 testing and validation phase was issued under a new version number (AIXM 5.1) in 2009. This is the version that was proposed for the initial operational implementation of Digital NOTAM.

The Trial has demonstrated that with a relatively small investment (200 k€) it is possible to develop a basic HMI that can be successfully be used by today’s NOTAM operators to provide the desired Digital NOTAM output.

More technical details about this trial are available on this website.

Digital SNOWTAM Pre-Operational Trial

Airlines and other airport users need accurate and easy to understand information about the status of runway contamination with snow and ice, in winter operating conditions. To address this need, EUROCONTROL developer the trial Digital SNOWTAM application. It made SNOWTAM information available in the form of an Airport Overview map, providing the contamination status of airports in a geographical area (Europe). The application used the AIXM 5.1 surface contamination model which provides this data in a format that enables fast graphical visualisation and enhanced services through the use of AIXM 5.1 capable data input interfaces.

The Digital SNOWTAM Application trial ran between 2009 and 2016 and was discontinued this year. A new Digital SNOWTAM application is being developed which will focus primarily on providing SNOWTAM data (in AIXM 5.1 format) through a SWIM compliant web feature service (WFS). This way the application can

  • Be used by third party applications and
  • Provide additional views, by combining the surface contamination information with other airport information such as capacity, runway usage, other local events impacting operations and diversion capability.

This new version is expected to be rolled-out in the first part of 2017.


Elements of the future Digital NOTAM concept of operations were discussed during the Digital NOTAM Workshop #2 of November 2007. This activity will now be continued and expanded by EUROCONTROL and FAA, to cover all aspects of the digital NOTAM process, from information origination to the end user. The aim is to develop a concept that is applicable worldwide, taking into consideration constraints such as the slow adoption of digital NOTAMs for certain regions of the world.

It shall be noted that Digital NOTAM is not an attempt to centralise the NOTAM creation in Europe. On the contrary, the creation of digital NOTAM has to take place as close as possible to the source of the event (Airport Manager, ATC Unit, civil-military cell, etc).

The availability of a PENS-like ground network in Europe is a pre-requisite for Digital NOTAM. The usability of the ICAO AMHS will also be investigated, especially for world-wide implementation, but this could result in some service limitations.

There is little doubt that digital NOTAM are needed. The real challenge is how to implement it in order to minimise the cost and maximise the benefit for the stakeholders. To answer this challenge, the Digital NOTAM Project intends to work along the following lines:

  • incremental approach, with focus on quick-wins;
  • re-use of existing and near-term investments (EAD, PENS, etc.);
  • development of open source software modules in partnership with industry;
  • strong cooperation with FAA, to share conceptual and specification development costs.

Incremental approach

An incremental approach is to be considered, focused on those information categories where there is an immediate benefit and where the end users are capable in the short term to exploit the digital NOTAM information. Initial candidates are airport surface NOTAM that could be embedded in Electronic Flight Bags and airspace/route restriction/availability NOTAM that could benefit to civil and military airspace users. Digital NOTAM in Europe is expected to become available with the new ATM Information Management System (EAIMS) around 2020.


It is estimated that more than 50% of the implementation cost will be re-training of NOTAM operators. It is a challenge to move from text to structured information.
To reduce the cost and to ensure harmonisation, an initial digital NOTAM training module could be developed centrally by EUROCONTROL and made available to the national training centres. The application already developed for the Digital NOTAM Trial could be used as a baseline for this.