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Version 2.0 - WORK IN PROGRESS!

Only the parts of the future version 2.0 that are considered sufficiently stable are provided here, for public review.

Digital NOTAM concept

The current Notice to Airmen (NOTAM) is a text note, which can be distributed by basic teletype networks such as the Aeronautical Fixed Telecommunication Network (AFTN). The NOTAM is intended to be read by pilots, controllers and other operational personnel involved in flight operations.

By contrast, a Digital NOTAM is a small data set, made available through more advanced communication networks (such as AMHS, TypeX, etc.). It is intended to be read and processed by automated systems, which in turn will convert it into text and graphical formats for presentation to humans. Digital NOTAMs 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. A Digital NOTAM might also trigger automated actions, such as determine procedures impacted by the unavailability of a navaid.

In order to encode the NOTAM digitally, all the information currently exchanged by NOTAM needs to be modelled and specified in a logical information exchange model. This was achieved with the Aeronautical Information Exchange Model (AIXM) version 5. In addition to the model, a number of rules and guidelines are necessary in order to harmonise the encoding of the different categories of NOTAM events.

A situation that affects one or more aeronautical features, by altering their properties, either temporarily or permanently and which requires specific encoding, decoding and verification rules in AIXM is described in this document as an “event scenario”.

For many years, Digital NOTAMs will be issued in parallel with the legacy text NOTAM. For this reason, the automatic generation of the legacy text NOTAM is also in the scope of this specification. Therefore, the text NOTAM generation rules are described for each particular scenario. This should avoid the manual creation on a different system and the risk of inconsistencies that could otherwise exist between the NOTAM text and the digital encoding.

Digital NOTAM will most likely be implemented incrementally: the most common types of NOTAM will be supported first, in order to match the gradual implementation by the end-user of their capabilities for digital NOTAM processing. Therefore, the Digital NOTAM Specification document will also be developed incrementally.

Purpose of this document

The Digital NOTAM Specification defines the rules for harmonised encoding of NOTAM information as digital AIXM data sets (version 5.1 or later). This document is intended primarily for system developers, as most of these rules will have to be translated into computer code that results in database structures, human-machine interfaces (HMI), 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.

The main goal of the document is to enable the interoperability of the different systems that produce, transform, transmit and consume Digital NOTAM data, as part of the digital aeronautical information in general. The application of common rules is also expected to reduce the cost of the implementation because it minimises the need for mapping and adaptation of the data coming from different sources.

The rules specified for different events (scenarios) describe the minimal information necessary to be provided on short notice. In certain situations, this might be supplemented later with more detailed information in order to provide all the detail necessary for recording a permanent change of the aeronautical feature concerned and which is not available for the initial notification.

The Digital NOTAM Specification is likely to evolve in future towards covering all the data necessary for aeronautical information updates, including changes of lasting duration to aeronautical "static" data.

Status of this document

This document shall be considered as guidance material, not as a normative specification. It provides a common baseline for developers of both Digital NOTAM production systems and digital data user systems. After sufficient experience is gained with practical implementations, the Digital NOTAM event scenarios might evolve towards a normative specification status.

While the final objective is to have an exhaustive description of all possible event scenarios and situations, it must be recognised that this cannot be achieved from the first step. Therefore, the initial editions of this document focus on describing the encoding rules for the most common NOTAM situations and which also have high potential for digital use. For this purpose, the document is organised in “increments”, with the first increment containing some very common events (airport closure, new obstacle, navaid unserviceable, etc.).

Implementers might be confronted with the requirement to support event scenarios that slightly deviate or that are not fully described in this document. The Digital NOTAM encoding event scenarios might need to be adapted and extended in order to match the local needs. However, if these deviations and extensions follow the common encoding rules provided in this document, the interoperability between different systems will be preserved. The data encoding rules for each scenario for Increment 1 scenarios are considered stable and unlikely to change significantly in future.

The data encoding rules for Increment 2 still need to be validated by implementation and therefore are likely to suffer amendments in future editions. For both increments, the text NOTAM production rules might still change, as a consequence of the “NOTAM Templates” work currently done by OPADD Focus Group of Eurocontrol. Once that is finalised, the Digital NOTAM Specification will be updated in order to support the latest version of the NOTAM Templates.

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