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Remark: At present, assessment of runway visual range using forward scatter meters is not
approved for use at United Kingdom aerodromes. Costs of installation of transmissometers for the
measurement of instrumented runway visual range are considered prohibitive for most aerodromes
offering CAT I operations. However, the United Kingdom expects to introduce assessment of
runway visual range using forward scatter meters in the near future.
Half-hourly METAR is issued for flight planning and local special reports for arriving and
departing aircraft. SPECI reports are not issued.
Remark: The requirement to produce SPECI has significant cost implications for United Kingdom
aerodromes, with little perceived benefit. Detailed analysis of the cost versus benefit will be
carried out. If this is a justified cost, this could be introduced in 2007.
WAFC London will continue to issue amendments to forecasts of significant weather using
abbreviated plain language messages but will not issue amended BUFR files.
Remark: Introduction and use of amended BUFR files is not yet at a sufficiently mature stage to
warrant operational usage. Further consideration of requirements for significant weather forecast
amendments will be given by the WAFS Operations Group.
* Recommended Practice
2 UNITED KINGDOM SUPPLEMENT TO ANNEX 3 (FIFTEENTH EDITION)
APPENDIX 3
2.3.1 c) Requirements for the issuance of local special reports will include criteria for increases in air
temperature from 6 October 2005.
Additional visibility thresholds of 2 000 m, 5 000 m (irrespective of numbers of VFR flights) and
10 km are used. Additional visibility thresholds of 150, 350 and 600 m will be used where an
RVR is not available, by local arrangement at each aerodrome.
Remark: Criteria exceed ICAO SARPs.
Special reports for RVR will only be prepared by local arrangement at each aerodrome.
Remark: To reduce the number of updates to the ATIS that would be required in fluctuating
visibilities, special reports for RVR are not carried out routinely; however, they are provided at
individual aerodromes as agreed between the United Kingdom MET Authority, the ATS unit and
the aerodrome operators.
Additional cloud base thresholds of 300, 700, 1 500 ft (irrespective of numbers of VFR flights)
and 2 000 ft for cloud layers of BKN or OVC extent are used.
Remark: Criteria exceed ICAO SARPs.
Observations of vertical visibility are not made.
Remark: There is no operational requirement in the United Kingdom for observations of vertical
visibility.
Variations from the mean wind direction during the past 10 minutes are reported in: b) 1) when the
wind speed is more than 3 kt and in b) 2) when the wind speed is 3 kt or less.
Remark: High costs to make change with little perceived benefit.
In local routine and special reports, the visibility reported is the prevailing visibility, supplemented
by runway visual range measurements, where appropriate.
Remark: Visibility reported in the METAR is the same in local and special reports for consistency.
Runway visual range on some runways intended for Category I instrument approach and landing
operations may be assessed by human observer. Further information is given in the United
Kingdom AIP GEN 3.5.
Remark: Not all aerodromes with CAT I operations have instrumented RVR installed.
RVR trends and significant variations are not reported.
Remark: There is no operational requirement for RVR tendency to be included in the METAR
report.
* Recommended Practice
15/6/05
4.9.1.5*
Table A3-2
APPENDIX 5
1.3.1* b)
Sensors to determine cloud amount and height of base cloud for local routine and special reports
are sited to give suitable indications of the height of cloud base and cloud amount at the threshold.
Remark: Sensors are typically located on the aerodrome.
Observations of vertical visibility are not made.
The reporting of clouds in the METAR of operational significance will be introduced on
6 October 2005. From this date, the abbreviation NSC (no significant cloud) will be used if there
are no clouds of operational significance, no TCU or CB; the abbreviations CAVOK and SKC are
not appropriate.
Remark: There is no operational requirement for observations of vertical visibility.
Information on wind shear is not added to METAR reports.
Remark: Consultation on the requirement for information on wind shear in METAR reports will
be carried out. If required, this could be introduced in 2007.
Ten-minute automated reports from equipment located on some off-shore structures contain
information onthe state of the sea (specifically mean wave height, maximum wave height and
wave period). This information is available in the associated meteorological forecast office.
　
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