AMOSSG/5-SN No. 14

16/3/05

AERODROME METEOROLOGICAL OBSERVING SYSTEMS STUDY GROUP (AMOSSG)

FIFTH MEETING

Montreal, 11 to 14 April 2005

Agenda Item	6:	Aerodrome forecast requirements

CRITERIA FOR TREND FORECAST REQUIREMENT

(Presented by W. Woveris)

SUMMARY
This paper outlines the user's views that TREND Forecast should only be required when justified and that global criteria should be developed.

1.	INTRODUCTION

1.1	The recent update of the EUR Regional Air Navigation Plan FASID Tables introduces TREND forecast requirements for many European aerodromes, in locations where no user requirement was perceived. TREND forecast are expensive and should be based on global, well-defined criteria. The following discussion highlights the IATA views.

2.	DISCUSSION

2.1	TREND Forecast

2.1.1	IATA noted with concern in the updated EUR FASID table MET-1A the numerous new requirements for TREND-type forecasts in some States. As an example, and using the EUR FASID table MET-1A, TREND forecasts in the UK are produced for only a handful of aerodromes (4), compared with 38 aerodromes in France and all international aerodromes in some States!

2.1.2	The requirement for TREND has so far been based on the frequency of the traffic and climatological conditions at the aerodrome concerned. Actually, the amendment to the BASIC OPERATIONAL REQUIREMENTS AND PLANNING CRITERIA (BORPC) section of the EUR ANP will include provisions (para 86) already implemented in the CARSAM ANP BORPC: "The determination of the aerodromes at which landing forecasts are required should take into consideration relevant operational and climatological factors, including the weekly number of flights requiring those forecasts and the incidence of adverse weather conditions." IATA strongly supports this provision.

2.1.3	Accordingly, criteria for defining when an aerodrome METAR should have a TREND forecast should be developed and, by being included in Annex 3, globally applicable.

2.1.4	IATA cannot support any requirement for TRENDs to be included in table MET 1-A unless they are based on the international requirement quoted in paragraph 2.1.2. This is not only a cost related issue, but also an issue of limited benefit of TRENDs to most international airline operators, for which sector length and pre-flight preparation time exceed two hours. TREND mainly has value for domestic operations with short sectors, but this should not be covered by Annex 3 nor charged to international flights.

2.2	TREND forecast cost

2.2.1	TREND forecasts include significant work for forecasters, equivalent to a TAF, and need to be produced at shorter intervals (30 to 60 minutes) than TAF, thus increasing the total cost. Estimates of TREND forecast costs vary depending on the individual States. However the following data illustrates the costs involved:

a)	UK: costs of around 16,000 UK £ per aerodrome per year, as reported by the Met Office.

b)	Helsinki aerodrome: estimated 140,000 per year, as reported by an operator.

3.	ACTION BY THE AMOSSG

3.1	The AMOSSG is invited to:

a)	note the content of this working paper; and

b)	develop global criteria for TREND requirements, to be included in Annex 3.

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