TAF love Technology and humans combine to create those vital pieces of pilot information known as terminal aerodrome forecasts By Captain Chris Leech, Log Board member You have just reported, checked in on your company’s IT system, and accessed the data for the flight(s) you will be doing. One of the first things you will look at are the TAFs for the relevant airports – but have you ever wondered who produces these, and how they got there? Well, if it’s a UK airport, the short answer is the Met Office. The Met Office produces TAFs for 57 airports throughout the country. Twenty years ago, many airports would have had a meteorologist doing this on site, but now the job is done at the Met Office’s HQ in Exeter and in its regional centres at Aberdeen and Belfast. While the process relies much more on automated technology than previously, the Met Office is keen to point out that there is still a large human input into TAFs. It works like this: meteorological data is collected from sources such as radar and satellites, and fed into computers that produce a generalised model of the weather within the UK region. Then, Met Office meteorologists add the human input to take account of local circumstances. Take London airports, for example: while they are geographically close – and so likely to be experiencing the same general weather pattern – Heathrow is in an urban environment, while Gatwick is surrounded on three sides by the River Mole, so has a greater degree of moisture in its vicinity. Luton, on the other hand, sits on top of a low escarpment, subjecting it to the localised orographic effects. Work to produce TAFs is done at seven ‘forecast benches’ located at the Met Office centres. Each has a qualified meteorologist, is staffed 24 hours a day in 12-hour shifts, and takes responsibility for 10 to 15 airports in a geographical area – for example, south-east England, Scotland, northern England, and so on. Frequent updates Many TAFs are produced every six hours, but the length of validity of a TAF depends on the type of traffic an airport receives. A Heathrow TAF will cover 30 hours (updated six hourly) to cater for long-haul traffic, but a regional airport – such as Exeter – will get a nine-hour TAF, updated every three hours. MANY TAFS ARE PRODUCED EVERY SIX HOURS, BUT THE LENGTH OF VALIDITY DEPENDS ON THE TYPE OF TRAFFIC AN AIRPORT RECEIVES All TAFs are reviewed constantly by the meteorologists and are subject to amendment if the forecast detail is expected to change markedly. Apart from the production of TAFs, the meteorologists are responsible for many other aviation forecasts, including SIGMETs, and can take a view on the accuracy of the general model. Away from the Met Office’s centres, onsite forecast capability is maintained at Heathrow and Swanwick, the latter to support safe and efficient en route flying and enhance collaborative decision-making. METARs, on the other hand, are produced locally – and, as we all know from the robot voices on the ATIS, are increasingly automated. Once the TAFs and other forecasts are produced, they are distributed to NATS Data Services for inclusion in global bulletins and onward transmission to third-party flight- planning providers used by our airlines. The Met Office also makes them available to the general aviation community via a web portal. WEATHER