Introduction

Because of the limited character set supported by the AFTN network, NOTAM messages are constrained to be transmitted in full uppercase. This section presents an number of discusses issues related to this limitation, in particular from a human factors point of view, and discusses how the digital . It also explains how Digital NOTAM can provide more user friendly text outputs by applying the appropriate mix of uppercase and lowercase text.

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However, information to operational personnel in preparation of a flight is provided throughout the Pre-flight Information Bulletin (PIB) in full upper case format, because this is how NOTAM are received through AFTN. A PIB can be a document of 10 pages or more., written in full upper case!

The American Institute for Research (AIR) performed on behalf of the Federal Aviation Administration (FAA) of the USA studies during 2007-2009

addressing challenges associated with the NOTAM system. The objective was to identify and eliminate human performance barriers and hence to improve safety. The studies were performed by gathering information from commercial airline pilots, commercial airline dispatchers and general aviation pilots’ pilots on their user experience of with NOTAM messages.

The studies identified that the formatting of the NOTAM makes them difficult to read and understand by pilots. It highlighted issues concerning uppercase text and translation of abbreviations and acronyms. These factors were considered making the NOTAM difficult identified as causing difficulties to read NOTAM and process it, increasing the workload and the possibility of error. Amongst Among the items on the pilots’ wish-list for improvement in processes and functionality when using NOTAM data the following were identified:

• To to have digitized NOTAM data to would enable sorting and filtering of messages and translation into multiple formats, e.g. ICAO NOTAM format, plain language and graphical representation.
• To to improve the NOTAM format by e.g. reducing/eliminating the use of contractions (abbreviations and acronyms) and the use of capital letters in the free text.
  

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The use of uppercase in the traditional ICAO NOTAM is due to the character set limitations of the Aeronautical Fixed Telecommunication Network (AFTN). Digital NOTAM are not constrained by this AFTN limitation and a conventional mix of uppercase and lowercase can be used when generating the Event NOTAM text. The distribution of Digital NOTAM can be made through other networks than AFTN and can be used directly for enhanced PIB (ePIB).  For legacy users, the Event Digital NOTAM text can be automatically converted into the ICAO format (all uppercase), thus satisfying the constraints AFTN transmission and for the traditional ICAO Pre-flight Bulletin (PIB) briefing.

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In order to achieve an optimum mix of uppercase and lowercase text in the digital NOTAM output, styling rules for the digital NOTAM decoding templates need to be specified. While sentence case [1] formatting will be used in general, for abbreviations and acronyms the use of upper case can improve the readability of the information.

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The Single European Sky ATM Research and Development programme (SESAR) delivery “Generic SESAR Information Presentation Guide” [2] 

from 2013 provides guidance on how to achieve an effective information presentation for the main actors involved in the ATM field. It provides guidance on presenting information:

• In a clear and unambiguous form.

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• In a format that calls for the attention of the users.

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• In the right location.

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• With the appropriate level of content and in the right format.

Regarding usage of uppercase and lowercase in information the SESAR guidance recommends the normal sentence case. The use of all uppercase should be avoided because it reduces reading speed and renders words indistinguishable.

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Pilots’ ideas on how briefing applications could support identifying abbreviations in the ePIB and display the explanation on less known abbreviations/acronyms were collected. This allowed the digital NOTAM text to be enhanced with mark-up elements, so that briefing tools/applications can identify abbreviations and offer either pop-up explanations or full expansion of less known abbreviations.

2.6          Within the AIS Stakeholders’ working arrangements of EUROCONTROL, the AI Operations Sub-group discussed during 2012 the usage of abbreviations in NOTAM. The Sub-group prepared input to ICAO proposing to indicate in ICAO Document 8400 (Abbreviations and Codes) 

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It was proposed to spell out abbreviations and acronyms which are not common and can be subject to misinterpretation. Also, with the digital NOTAM developments in mind (e.g. no AFTN constraints), words such as “closed”, “available”, “activation”, “active”, “activated” and “unserviceable” were proposed to be spelled out instead of using the abbreviations. However, many abbreviations were recognised to be kept, such as “RWY”, “TWY”, “ILS”, “VOR”, “ATS”, since their meaning is so well known and the abbreviation/acronym is perceived as a word.

2.7          The EUROCONTROL Pre-digital NOTAM Templates document 

  applies to a certain extent the principle of spelled out text in item E on words such as “closed”, “available”, “activation”, “active”, “activated” and “unserviceable”, and on acronyms that are not commonly known.

Proposed approach

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1.2          Uppercase characters shall always be used for:

The first letter in a sentence.

Each first letter of a name (such as 'Brussels South')

Each first letter of certain acronyms that are spelled out

Note: To be discussed to which acronyms this rule shall apply to avoid uppercase text such as “Climb To And Maintain”, “Feet Per Minute”, “TouchDown Zone”.

Note: acronyms to which this rule does not apply: airspace types (such as TRA - will be written "temporary restricted area"), etc.

Acronyms that are not spelled out (such as VOR, SID, NOTAM, AIP, etc.).

Location indicators.

Designators (such as five-letter ICAO designators for waypoint, navigation aid designators, route/SID/STAR designators, airspace designators, etc.).

Specified abbreviations (see paragraph 5.5).

1.3          Lowercase characters shall always be used for:

·         Consecutive text after the first letter in a sentence.

·         Abbreviations[PE3] , except those specifically mentioned as to be written otherwise.

·         Spelled out abbreviations and acronyms.

1.4          Mix of uppercase and lowercase

·         Unit of measurements shall be spelled in accordance with SI units.

1.5          Specific rules for abbreviations[1]

·         The abbreviation and uppercase shall always be used for:

o   RWY, TWY, THR, AWY, ATS, ARP and the different air traffic services types (e.g. AIS, FIS, AFIS, TWR, ACC, APP).

o   Area types CTA, UTA, TMA, CTR, FIR and UIR.

o   Days and months (MON, TUE, WED, THU, FRI, SAT, SUN, JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC).

·         Abbreviations that shall be spelled out:

o   Single words such as “closed”, “unavailable”, “activated”, “between” with the exception of “AD”.

o   Colours.

o   Cardinal points and their combination.[PE4] 

o   Abbreviations/acronyms that are not commonly used, not included in ICAO Doc 8400  and/or may be subject to misunderstanding (e.g. use ‘area chart’ instead of “ARC”).

1.6          Digital NOTAM text examples with these applied rules:

·         ILS/DME RWY 19 unserviceable.

·          RWY 01 closed.

·         Temporary Reserved Airspace ESTS310 activated. 

·         THR RWY 19 displaced 400m. Declared distances changed: TORA 2450m, TODA 2450m, ASDA 2450m, LDA 2050m.

·         Trigger NOTAM – perm AIRAC amendment 02/14 WEF 20 FEB 2014: new ATS route M123 established.

·         VOR DKB resumed normal operations.

·         Danger Area HED9 activated.

·         ATS operating hours changed as follows: 01 03 05 1000-1600 02 04 06-31 0800-2200.

·         EGNOS is not available for LPV.

·         AWY G5 closed between WIL and FRI.

·         RNAV route N850 closed between GERSA and ODINA.

·         Temporary Restricted Area Narnia established.

·         Temporary restricted area Narnia established.

·         Crane position 500545N 0141556E erected 190m south of RWY 13/31 axis, 1300m behind THR RWY 31, elevation 390.3m height 20.7m AGL.

·         ILS RWY 25R unserviceable.

·         TWY A east of RWY 10/28 closed.

·         Minimum Sector Altitude southwest sector raised to 1700ft AMSL.

Discussion in the Focus Group:

-       Doubts about ATC, they might not like the change from Upper case to sentence case. Therefore a warning could be added in the specification that the presentation of the NOTAM text to specific groups of users should be verified first. For pilots there is no doubt, they prefer sentence case (see ePIB). For users that prefer upper case only, the conversion in straight-forward.

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OTHER Aspects

-       NOTAM reason for closure or similar, are they really necessary in a NOTAM?

-       Use of NOTAM for NIL digital data set notifications

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Reference documents

[1]Sentence case: the standard capitalisation of a sentence with the first letter uppercase and subsequent letter lowercase with exceptions such as proper nouns or acronyms.

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