AMOSSG/4-SN No. 4

26/6/03

AERODROME METEOROLOGICAL OBSERVING SYSTEMS STUDY GROUP (AMOSSG)

FOURTH MEETING

Montreal, 15 to 18 September 2003

Agenda Item	7:	Aerodrome forecast requirements

OVERVIEW OF PAST AND EXPECTED PROGRESS WITH RESPECT TO AERODROME FORECAST REQUIREMENTS

(Presented by the Secretary)

SUMMARY
Two longstanding tasks are presented to the group for consideration.

1.	INTRODUCTION

1.1	This paper summarizes three longstanding tasks where little progress has been made over the last few years and which have now been assigned to the work programme of the group.

2.	DISCUSSION

2.1	Review of the forecast accuracy requirements

2.1.1	The Air Navigation Commission took action on a proposal made by theWorld Meteorological Organization (WMO) that the forecast accuracy requirements currently given in Attachment E to Annex 3 — Meteorological Service for International Air Navigation should be reviewed.

2.1.2	The group may wish to note that Amendment 73 to Annex 3, (still subject to adoption by the ICAO Council), will make minor editorial adjustments to the titles of Attachment E. However, the meteorological content of the Attachment, which will become Attachment B, will remain unchanged through Amendment 73.

2.1.3	It is expected that a proposed change to Attcahment E to Annex 3 will be provided by the users and in particular, by the International Air Transport Association (IATA). The group may wish to consider the updating of this Attachment for those elements relating to aerodrome operations and furthermore to refer those requirements relating to en-route forecasts to the World Area Forecast System Operations Group (WAFSOPSG) for its consideration.

2.2	The operational feasibility and desirability of requiring a greater accuracy in the first three hours of a TAF

2.2.1	The Commission took action on a proposal to study the operational feasibility and desirability of requiring a greater accuracy in the first three hours of a TAF. This matter was referred to the group for consideration with the view that this could be achieved by, inter alia removing the use of the term "PROB" from the forecast during the first three hours or by introducing a more flexible update frequency.

2.2.2	The group may wish to discuss the feasibility and desirability for such an improvement in forecast accuracy bearing in mind the cost implications in terms of the software changes that would be required in order to accommodate such a change. Furthermore, should such a requirement exist, then the group may wish to consider the two proposed solutions given in 2.2.1 and the development, by the Secretary, of a draft amendment to Annex 3 in time for the AMOSSG/5 Meeting.

2.3	Monitoring the development of techniques for forecasting runway visual range (RVR)

2.3.1	A longstanding task of the ICAO Secretariat is to monitor the development of techniques for forecasting RVR which was originally formulated at the COM/MET/82 Divisional Meeting. This issue has been studied more recently by the MET/AOP PT in the EUR Region although it concluded that no satisfactory techniques exist at present and the study has been held in abeyance pending any further progress made by States.

2.3.2	The group may wish to note the progress made and to provide reports as appropriate on any progress made in the development of techniques for forecasting RVR.

3.	ACTION BY THE GROUP

3.1	The group is invited to:

a)	agree that Attachment E to Annex 3 should be updated for those forecasts relating to aerodrome operations based on input from IATA;

b)	agree that proposals for the updating of Attachment E to Annex 3 relating to en-route forecasts should be referred by the Secretary to the WAFSOPSG for consideration, and

c)	assess the operational feasibility and desirability for a greater accuracy in the first three hours of a TAF and, if necessary that the Secretary should prepare a draft amendment to Annex 3 in time for the AMOSSG/5 Meeting.

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