ACP-WGM18/WP- International Civil Aviation Organization
WORKING PAPER
AERONAUTICAL COMMUNICATIONS PANEL (ACP)
15th MEETING OF WORKING GROUP M (Maintenance)
Bangkok, Thailand 31 January – 1 February 2011
Agenda Item :
Review of the Attachments to Annex 10 Volume V
(Presented by John Mettrop, UK)
SUMMARY This paper reviews the content of the Attachments to Annex 10 Volume V and raises a number of issues where the information contained is unclear with respect to the assumptions made and how the calculations are performed. The paper therefore suggests that a number of sections are reviewed with a view to introducing greater clarity as to how the calculations have been made and the assumptions made. ACTION The working group is invited to:- Note the Paper To forward to Working Group F for action with respect to re-writing the attachments to Annex 10 Volume V to clarify the assumptions and calculation methodology used in the calculations contained in the attachments
(3 pages) 0000ecaa45fb4acae154e425abdc282c.doc 2 ACP-WGM14/WP-05
1. INTRODUCTION
1.1 In March this year ICAO carried out an audit of the UK Civil Aviation Authority. In preparation for that audit the CAA carried out a complete review of compliance with the various Annexes of the Convention on International Civil Aviation.
1.2 Whilst undertaking that review a number of anomalies were discovered as well as areas where the text might be improved to aid clarity when reading the documents. For Annex 10 volumes I, III, IV & V, where surveillance and spectrum management have an interest, it was agreed that these anomalies should be brought to the attention of ICAO through input contributions to the appropriate Working Group.
1.3 In November 2009 at WG-M I submitted Working Paper 5 that addressed a number of proposed changes to the white pages of Annex 10, volume V. That paper whilst noting that there were some inconsistencies and a lack of clarity that need to be addressed in the attachments to Annex 10 volume V but did not propose solutions to these issues.
1.4 This paper identifies those inconsistencies and the areas where greater clarity is required with respect to assumptions made or the calculations performed within the attachments to Annex 10 volume V.
2. DISCUSSION
2.1 The Attachments to Annex 10 Volume V provides guidance on the deployment of VHF communications systems and LF/MF navigation systems and the protection from harmful interference. This material is used as the basis for planning rules used throughout the world for these systems. With the growth in aviation, the number of systems has increased and hence the pressure to ensure that planning criteria are optimal has also increased.
2.2 The calculations contained in the current attachments appear to make a number of assumptions/apparent inconsistencies in the input parameters and calculation methodology that are not clear in the document but are crucial to understanding how those criteria might be able to be improved. A number of examples based on attachment A section 2 are provided below:-
Attachment A, Paragraph 2.4, 1st bullet: There is a reference to the ITU-R curves for 100 MHz vertical polarization over land but do not provide the recommendation that is being used as a reference. A related issue is that the curves provided in figures A8 - A-15 are for 127 MHz.
Attachment A, Paragraph 2.4, 2nd bullet: The minimum field strength at limit of functional service range of 45 dB above 1 microvolt. However Annex 10, Volume III, Part 2, paragraph 2.2.1.2 recommends that on a high percentage of occasions the effective radiated power should be such as to provide a field strength of at least 75 microvolts per metre (37.5 dB above 1 microvolt) within the defined operational coverage of the facility. These two figures appear to be in contradiction which I assume is to take into account the statement about on a high percentage of occasions but nothing is stated. 3 ACP-WGM/WP-
Attachment A, Paragraph 2.4, Associated note: It is quoted that to meet this requirement, a station radiating 100 W should be no more than 185 km from the limit of it’s service range. How is this calculated and what assumptions have been made.
Attachment A, Paragraph 2.4, 3rd Bullet: There are two assumptions about the power radiated dependent on the service provided but this does not take account of ATIS/Volmet services. Should these be assumptions based on the service volume.
Attachment A, Paragraph 2.4, 5th bullet: What is the improvement factor that has been assumed between the signal at the receiver input and the receiver output?
Attachment A, Paragraph 2.5, 2 bullet: A number of adjacent channel rejections are quoted here but it would be useful to show how these are calculated.
Etc.
2.3 For improved clarity it is proposed that Working Group F of the Aeronautical Communications Panel be requested to, in conjunction as necessary with the Spectrum Sub-Group of the Navigation Systems Panel, to review and update the text contained in the Attachments to Annex 10 Volume 5 to improve clarity and transparency of the calculations.
3. RECOMMENDATION
3.1 That Working Group F of the Aeronautical Communications Panel be requested to, in conjunction as necessary with the Spectrum Sub-Group of the Navigation Systems Panel, review and update the text contained in the Attachments to Annex 10 Volume 5 to improve clarity and transparency of the calculations.
4. ACTION BY THE MEETING
Note the Paper To forward to Working Group F for action with respect to re-writing the attachments to Annex 10 Volume V to clarify the assumptions and calculation methodology used in the calculations contained in the attachments