The current Notice to Airmen (NOTAM) is a text message, which includes some structured 'NOTAM qualifier' fields. NOTAM are distributed through basic teletype networks such as the Aeronautical Fixed Telecommunication Network (AFTN). The NOTAM content is intended to be read by pilots, controllers and other operational personnel involved in flight operations. There are increasing complaints about the usability of the NOTAM system due to aspects such as:
- NOTAM proliferation - the number of international NOTAM messages has tripled in the last 10 years, approaching 1 million per year;
- use of only upper case (an AFTN character set limitation) - which makes the NOTAM difficult to read, especially when compiled in long pre-flight information bulletins
- the free text nature of the NOTAM, which makes any parsing and automatic processing almost impossible.
Therefore, a Digital NOTAM concept has been proposed, by which the NOTAM information will be provided as fully structured data set through digital data services. AIXM version 5.1 and further versions support the provision of truly Digital NOTAM. These can be used, for example, in order to present an updated airport diagram to the pilot or to the air traffic controller, containing graphical depictions of the work in progress areas, closed taxiways or runways, temporary obstacles, etc. Digital NOTAM enable the provision of pre-flight pilot briefings in normal sentence case, which should significantly improve their readability and the visual comfort for the user. The processing of a Digital NOTAM might also trigger automated actions, such as determine procedures impacted by the unavailability of a navaid.
Digital NOTAM Specification
In addition to the AIXM model itself, a number of rules and guidelines are necessary in order to harmonise the encoding of the different categories of NOTAM events. For this purpose, a Digital NOTAM Specification is being developed.
A first version of the Digital NOTAM Event Specification was published in 2011, providing rules for harmonised encoding of the most common NOTAM events (runway closure, airspace reservation, new obstacle, etc.).
This document is intended primarily to system developers, as most of these rules will have to be translated into computer code that results in database structures, human-machine interfaces, data validation rules, etc. However, the document is developed with significant input from operational experts, in order to capture all the rules and requirements that will guarantee safe, efficient and reliable Digital NOTAM operations.
A second version of this document is being developed, including support for more scenarios and also clarifications/corrections to the scenarios from the first version.
The US Federal Aviation Administration (FAA) has deployed a Digital NOTAM system at more than 300 US airports. This system enables airport managers to directly encode the data concerning a wide range of airport events. For this purpose, many more airport specific scenarios have been documented by FAA, which are considered in the development of the second version of the Digital NOTAM Event Specification. More information about the FAA Digital NOTAM is available from the FAA NOTAM System web site:
In Europe, the EUROCONTROL Centralised Services project plans to deliver a Digital NOTAM encoding capability through the European ATM Information Management Service (EAIMS).