What is a NOTAM?
There are a few things in aviation that have survived over the years with so little change as the NOTAM, in spite of its numerous, known shortcomings. NOTAM is a quasi-acronym for Notice to Airmen, a system of providing aeronautical information introduced well over 60 years ago.
NOTAMs… we have all seen them, worked with them and think we know them. But do we really?
A NOTAM is a text message, constructed using a code defined by ICAO and distributed via the Aeronautical Fixed Telecommunications Network (AFTN). It informs the recipients of immediate or temporary changes to the air navigation infrastructure, both airport and en-route. As an example, if a runway or part of a runway is temporarily closed, this will be announced in a NOTAM. There are several types of NOTAM but their essence and purpose is the same: provide vital information to airmen in a timely manner. In fact, the NOTAM is the middle part of the layered legacy system of information provision: the AIP (Aeronautical Information Publication) describes the big picture and the permanent situation; NOTAMs bring information about sudden/immediate changes and temporary changes that will exist for a short time only; and the operational radio, including broadcasts like the ATIS (Automatic Terminal Information Service), that announce sudden changes and continue to do so at least until the information is also available in a NOTAM.
The NOTAM offices of the world’s States are a legendary bunch of very independent minded experts, who know very well how important their job is and who tend to be slow with changes, however useful, lest the carefully thought out system fail in its purpose. Frustrating on occasion, it is hard to blame them for being careful.
NOTAM problems
Figuring out which NOTAM is applicable to a given flight is not always easy and it requires a major effort on the part of the pilot or, in the case of airline operations, the experts who put together the route documents for their flights. Missing a NOTAM that is there happens as does the case where a NOTAM that should be there is not there for any number of reasons. Clearly, the legacy NOTAM system, designed for the manual environment that is fast becoming a thing of the past, is ripe for renewal in the course of which the shortcomings can be eliminated.
The move towards increased automation in air navigation and air traffic management requires that all aeronautical information be available in digital form, suitable for automatic processing. The legacy NOTAM messages largely escape the digital processing data chain and as a result the contents of a database, be it on-board, at the airport or in an ATC system, may be ‘superseded by NOTAM’. In the current set-up, the task of remembering which information has been overridden becomes a task for the pilots or controllers, clearly a safety risk.
In order to satisfy end user needs for timely, accurate and complete aeronautical data and the SESAR goal of providing a composite, single picture of the ATM environment, available to all, a Digital NOTAM concept has been developed jointly by EUROCONTROL and the United States Federal Aviation Administration (FAA).
AIXM, the key to digital NOTAM
The key element of the Digital NOTAM concept is the Aeronautical Information Exchange Model (AIXM) version 5. AIXM has been used in Europe since 2001 in the European AIS Database (EAD) and by many national AIS systems provided by industry. The earlier AIXM versions 3.3 and 4.5 are de-facto standards for digital data encoding in the Aeronautical Information Service (AIS).
Since 2003, EUROCONTROL and the FAA have invested significant effort in upgrading AIXM in order to satisfy the needs of the future ATM system. This was finalized with the publication of AIXM version 5.1 in September 2009, including an UML class model, a “temporality” concept, an XML/GML schema and supporting material. AIXM version 5 enables the provision of all the data provided by AIS in a digital form.
Of particular interest is the AIXM 5.1 capability that enables the encoding of NOTAM information into a fully computer readable format. This was achieved by analyzing the information usually published in NOTAMs and extending previous versions of the model with the classes and attributes that are necessary for digital NOTAM encoding.
No more excuse for NOTAMs to flow outside the automated information management environment…
The digital NOTAM concept
The introduction of digital NOTAM removes the historical split between NOTAM and Aeronautical Information Publication (AIP) data, by which static (baseline) information is made available in paper format while last minute updates are distributed as AFTN messages.
This is the all important move from the “product” based approach to aeronautical information to a data-based one.
In the future, all traditional Aeronautical Information Service (AIS) products (AIP, NOTAM, AIP Amendments, charts, pre-flight information bulletins, etc.) will be generated from a coherent data source, which comprises both “static” and “dynamic” information. All the information will be available in the same digital form and from a single source. Users will also be able to define their own packages and create them from the data obtained from this single source.
Digital NOTAM will also support System Wide Information Management (SWIM) one of the most important pillars of the SESAR concept of operations.
Qualitative analysis has shown that, in the short term (2012-2017), Digital NOTAM will provide improved data quality and better data management, which will result in system-wide economies. Input forms will allow originators (such as airports) to pre-encode information, allowing NOTAM operators to focus on non-routine and supervisory roles. This will improve ANSP efficiency and the integrity of the data chain, as required by ICAO and in accordance with the Single European Sky regulations. Low-cost solutions will improve the accessibility of critical information to the VFR community, for example, through the graphical depiction of temporary airspace reservations, reducing the risk of airspace infringements.
The Digital NOTAM concept is applicable to both civil and military information. The provision of data updates in a common digital format will improve the interoperability of civil-military systems and will support flexible airspace usage.
In the medium term (2017-2020), Digital NOTAM will enable enhanced pre-flight briefing (graphical visualization, improved filtering capabilities). More importantly, it will enable the development of new services in which data is merged from different domains (airport, meteo, flow management, etc). This will support the provision of aeronautical information updates in flight. Information will be shared for incorporation into devices such as Electronic Flight Bags (EFB) and advanced navigation displays. These are expected to be standard equipment in the next generation aircraft of most categories. Benefits in terms of safety, ANSP efficiency, flight efficiency (contributing to fuel savings and the environment) and airline operations efficiency are expected as a result.
When will we see digital NOTAM in practice?
An initial Digital NOTAM Trial took place in 2008 with the participation of more than 40 NOTAM offices and system/service providers. The focus was on verifying the AIXM model and on explaining the digital NOTAM concept to NOTAM operators.
Operational Digital NOTAM deployment in Europe will start around 2012, full operational capability being expected by 2018. A similar implementation plan has been developed by the FAA, where the first digital NOTAM submission systems are already being deployed at some pioneer airports. The concept has been proposed for world-wide standardization and it is part of the ICAO AIS to AIM Transition Roadmap.
A live operational trial focused on SNOWTAM is currently taking place. SNOWTAM is a particular NOTAM category, dedicated to providing information about the status of the airport surfaces in winter conditions: contamination with water, snow, ice, etc., friction coefficient, cleared surfaces, etc. In the peak of the winter season in Europe, hundreds of such messages are issued daily.
Between November 2009 and March 2010, all SNOWTAM messages issued world-wide will be converted into AIXM 5 encoding and will be used for providing graphical visualization of the airport conditions (snow contamination, friction coefficient). Digital SNOWTAM data in AIXM 5.1 format will also be made available through a Web interface, applying a REST architecture.
Small steps perhaps but the implications are huge. A vital legacy system is being transformed into a new digital version, ready to be part of the forthcoming SWIM environment.
To obtain more information about the digital NOTAM concept and the trials, check out the xnotam website here or send email here.