AMOFSG/10-SoD
Appendix H
APPENDIX H DRAFT
DRAFT AMENDMENT TO ANNEX 3 —
METEOROLOGICAL SERVICE FOR INTERNATIONAL AIR NAVIGATION
(EIGHTEENTH EDITION — JULY 2013)
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PART II. APPENDICES AND ATTACHMENTS
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APPENDIX 3. TECHNICAL SPECIFICATIONS RELATED TO
METEOROLOGICAL OBSERVATIONS AND REPORTS
(See Chapter 4 of this Annex.)
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4. OBSERVING AND REPORTING OF
METEOROLOGICAL ELEMENTS
Introductory Note.— Selected criteria applicable to meteorological information referred to under
4.1 to 4.8 for inclusion in aerodrome reports are given in tabular form at Attachment C.
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4.5 Clouds
4.5.1 Siting
Recommendation.— When instrumented systems are used for the measurement of the cloud
amount and the height of cloud base, representative observations should be obtained by the use of sensors
appropriately sited. For local routine and special reports, in the case of aerodromes with precision
approach runways, sensors for cloud amount and height of cloud base should be sited to give the best
practicable indications of the cloud amount and height of cloud base and cloud amount at the middle
marker site of the instrument landing system or, at aerodromes where a middle marker beacon is not
used, at a distance of threshold of the runway in use. For that purpose, a sensor should be installed at a
distance of less than 900 to 1 200 m (3 000 to 4 000 ft) from before the landing threshold at the approach
end of the runway.
Note.— Specifications concerning the middle marker site of an instrument landing system are
given in Annex 10,Volume I, Chapter 3 and at Attachment C, Table C-5.
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