Cloud Height - AMSL/AGL References ATIS etc

[blueloo]

Does anyone know the reference for either Jepps or AIP to the cloud height datums for the ATIS, METAR, TTF METAR and TAF.


thanks

[Shitsu_Tonka]

AIP GEN 3.7

[blueloo]

Thanks ****su - that was 1 part I was looking for (Forecast section), but I think from memory there is a section for ATIS cloud Height Datum and METAR/Non-TTF Cloud Height Datum.


Both were found in rather obscure locations......

[Notaclue]

I think the obscure place you are referring to is AIP GEN 3.3 para 2.6.3, but it doesn't give the datum. The only place that I know of is GEN 3.5 para 3.7 as pointed out above. ARFORs are AMSL - all of the aerodrome info is above the AD reference point.

[Shitsu_Tonka]

Yes - I wonder if this has something that has slipped out of the docs? I seem to remember from ATPL/CPL studies (many years and many beers ago) that the references were all in AIP, including the MET section.

[blueloo]

still no luck for me, anyone else found the references yet?

[blueloo]

speaking of which, if anyone knows gary V.(the met instructor) at what used to be called BAFTA adelaide, he would know.......

[Ex Douglas Driver]

I also haven't been able to find anything in AIP, CAOs, CARs etc with specific reference to AMSL or AGL. The editors of AIP may be allowing assumption to be the mother of.....

From the Bureau of Met website:
http://www.bom.gov.au/general/reg/av...lanmetar.shtml

METAR/SPECI Format Explanation

Cloud height is given as a three-figure group in hundreds of feet above the aerodrome elevation, e.g. cloud at 700 feet is shown as 007.

http://www.bom.gov.au/general/reg/av...lanarfor.shtml

AREA FORECAST Format Chart Explanation

Description of cloud follows after the word 'CLOUD',

Using the following criteria.

• any cumulonimbus;
• any cloud at or below 5000 feet above the highest terrain in the area concerned by the forecast;
• any layer of more than 4/8 base at or below 21 000 feet above MSL, and
• any cloud associated with moderate or severe icing, moderate or severe turbulence, or precipitation mentioned in the forecast.
• The term 'LAYERS' is used if ST and/or SC are involved.
• When CU and SC are forecast and expected to be SCT or BKN, they can be combined as CU/SC.
• If subdivisions are used and one or more subdivisions have no cloud associated with it, the format is, A: NIL CLOUD.
• Cloud amount is given as 'SCT' (1-4 oktas), 'BKN' (5-7 oktas) or 'OVC' (8 oktas), except for cumulonimbus.
• Cumulonimbus cloud is mentioned first, then cloud with the lowest base, the next higher base second and then following cloud in ascending cloud base height.
• Cumulonimbus is described using 'ISOL' for individual cumulonimbus, 'OCNL' for well-separated cumulonimbus or 'FRQ' for cumulonimbus with little or no separation. 'EMBD' is added to other abbreviations to indicate cumulonimbus clouds that are embedded in layers of other cloud regardless of whether or not they are protruding from the layer.
• Cloud types are given using the abbreviations CU (Cumulus), SC (Stratocumulus), CB (Cumulonimbus), ST (Stratus), AS (Altostratus), AC (Altocumulus) and NS (Nimbostratus).
• When CU (Cumulus) and SC (Stratocumulus) or AC and AS occur together at similar heights, they may be combined; CUSC or ACAS. The cloud base and top are given in feet above MSL.

A slightly obscure place to find "operational" info.