As I've said before, NATS have been using SAMOS at LGW now for several years and as far as I'm concerned, this service is entirely adequate for our needs. Furthermore, I would say that Heathrow's needs aren't any more stringent than ours, merely a slightly different emphasis in one or two particulars. For instance, we are more interested in accurate cloud ceiling around the 700'-800' mark for Northern Runway ops; LHR have a greater interest in crosswinds for choice of runways. As far as LVPs are concerned at both airports; IRVR is derived from an entirely different system; cloud ceiling from the ceiliometer, not just human observation.
I think it needs emphasising that it isn't the job of the Assistant to compile the forecast from observations that they make; rather to verify that the automatic observations made are reasonable.
I would say that at our larger airports, where the vast majority of traffic is CAT II-capable and mostly CAT III-capable and where CAT I or 'visual' traffic simply can't get the slots, accurate reporting of weather parameters is less important than at airfields where a/c and pilots with less capable qualifications operate.
I've always had an excellent service from the Aerodrome Forecaster at Bracknell, now Exeter. Personally I always call already armed with the TAF, asking for perhaps some more detail as to timings or whether we're going to get snow or sleet etc. This is usually forthcoming and has been useful in decision-making. I certainly haven't heard anyone say that our TAF is any the less accurate than it used to be because the METAR data that forms a part of the information used to compile it is produced automatically rather than by human observation. There's more to a TAF than 3 METAR in a row, look at the TAFs for 3 airfields within reasonable distance of each other; notice the subtle differences coloured by the overall met. picture.
I'm quite surprised that LHR hadn't changed to SAMOS years ago; what was the reason for that?
Cheers,
The Odd One