The RAF had a long history of providing data for the Met Office, stretching back to February 1918 and the formation of the first Meteorological Flight at Berck in NE France (it was a RFC unit until 1 April 1918). This was disbanded in 1919, but two more Met Flights were formed in early 1920, one at Baldonnel, near Dublin, and the other at Upavon.
For various reasons these two were not a success (mainly because other units kept ‘borrowing’ their aircraft) but in November 1924 a truely independent Met Flight was formed at Eastchurch, but this soon moved – to Duxford in Jan 1925. The Met Flight moved to Mildenhall in Nov 1936, and two months later a second Met Flight was formed, this one at Aldergrove. It was with the first operational ascent by the Aldergrove Met Flight that the term THUM first appeared. It derives from Temperature and HUMidity, the two most important elements obtained during a meteorological ascent.
Despite this the units continued to be known as Meteorological Flights, and by the end of WW2 there were some 24 Met Flights operating in all the major war theatres. With the end of the war the need for the Met Flights soon disappeared as other means of gathering upper air data were developed.
However, in June 1946 Fighter Command started providing supplementary upper air data with a new THUM Flight. In fact it was not a single unit but a confederation of squadrons based at Coltishall and West Malling. The daily THUM flight (as it was now called) was flown in rotation by one of the three squadrons based at each airfield, 23, 141 and 264 at Coltishall, and 25, 29 and 85 at West Malling – all flying Mosquitoes. Each squadron had the task for about a month.
By 1950 the piston-engined Mosquitoes were being replaced by jets, which were unsuitable for the task, and the last RAF THUM flight was made from West Malling on 30 April 1951.
The following day a newly formed civilian THUM Flight, operated by Short Brothers and Harland, under the control of RAF Home Command, flew its first sortie from RAF Hooton Park. Flying RAF Spitfires the unit soon moved to RAF Woodvale where it remained for the next 7 years. The THUM Flight made its ascents over Worcester, and most were made at 1500 GMT. There were two fatalities during this time; Mr G Hargreaves died when his Spitfire crashed at Woodvale returning from a flight test on 4 May 1952. Mr T Heyes died on 4 March 1954 when his Spitfire crashed at Church Pulvernack in Shropshire whilst returning from a THUM sortie.
The last Spitfire sortie was flown on 10 June 1957. Flying Mosquitoes the THUM Flight remained in existence for a few more months, but the curtain came down with the final sortie on 1 May 1959.
Brian
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