Meteorological Reconnaissance A Brief Introduction (Part 2)
202 (Meteorological Reconnaissance) Squadron
By 1945 some 30 long range meteorological reconnaissance flights a day were being made the by the RAF in the Eastern Atlantic in addition to those being made by the American air forces. There were now some 100 Meteorological Air Observers at work. But, up to this point, 202 Squadron had played rather a small part
When peace broke out there was immediately a reduction in the requirement for meteorological reconnaissance flying: the need for accurate weather forecasts was less acute and civilian ships were once again able to report positions and weather in real time.
The Atlantic, however, remained the source of most of Britain's weather and the weather forecasting techniques of that era required the analysis by hand of charts plotted by hand with as much detailed weather data as possible. Professionally made weather observations from an area chosen by the forecasters were invaluable and the answer was still Meteorological Reconnaissance.
At the time 202 Squadron was performing anti-submarine duties at Castle Archdale. In 1946 they were disbanded for a short time before designated as a meteorological reconnaissance squadron up the road at Aldergrove with Halifaxes'.The Halifax lasted until 1950 when the Squadron re-equipped with the Hastings C Met Mk 1.The establishment was five aircraft on the Squadron and three in the hanger or at the MU.
The crew for a reconnaissance flight was 2 Pilots (one being Captain), Navigator, Engineer, 2 Signalers and 2 Air Meteorological Observers as they were now known. The "on duty" AMO occupied the right hand pilot seat.
AMOs were selected from experienced airfield observers of the Met Office and had perhaps unique conditions of service: they were signed on for two and a half years with an extension for a further two. This was a cunning Air Ministry ploy to ensure that no one qualified for any terminal grants or similar. It was not too unfair, however, as return to a job in the Met Office was guaranteed.
During the period of flying the Halifax the Squadron lost 32 aircrew in accidents; an enormous number for what may have seemed to many to be a cushy peacetime job. No further lives were lost in the following fifteen years of Hastings operation though one was written off and two were very seriously damaged in crashes.
The myriad of reconnaissance tracks being flown by several squadrons round the UK was rationalized into three: EPICURE from St Eval, NOCTURNAL from Gibraltar and BISMUTH from Aldergrove. By 1950, 202 Squadron flying BISMUTH from Aldergrove was the only one left. The Code name "BISMUTH",was formerly one single triangular track flown from Tiree by 518 Squadron, was adopted for the whole system with fifteen individual tracks being lettered from A to O. Normally only one track, chosen by the Meteorological Office's Chief Forecaster, was flown in daylight each day, but occasionally during exercises and alerts two or more, including a night one, were flown. Tracks fell into two main types: triangles and probes.
Triangles (A to G) were similar to the wartime ones but with the distance between observation positions increased from 50 to 60NM. The introduction of a radar altimeter (SCR 718) meant that the low level legs could now be flown at a fixed height of 1500 feet above sea level allowing the measurement of surface pressure at every observation point instead of only at the "sea level" ones as previously.
As an observation position was approached, the AMO, in the right hand front seat, would set his pressure altimeter accurately to 1500 feet and the pilot would copy this to his and fly at a precise height and steady airspeed until all measurements had been made. Steady airspeed was very important because, with dynamic heating and other factors varying with at least the square of the airspeed, small fluctuations in IAS meant a few minutes for the thermometers to settle down.
High level legs were still flown at the standard pressure level of 500 MB, just above FL180, but the advent of the SCR 718 meant that this height above sea level could be measured - a very valuable meteorological parameter. In fact the height was calculated from the temperature profile at the climb and descent positions and the radar altimeter was used to measure changes from that.
Remember that this was the infancy of civil trans-Atlantic flying creating a great need for upper air data and there were only nine ocean weather ships to provide it in the whole Atlantic. The high level observations from BISMUTH and its American cousins FALCON and GULL were invaluable.
The procedure for the soundings had been developed over years of experience and required a high standard of flying and crew co-operation. At the climb position the AMO made the routine 1500 feet observation and then the aircraft was taken down to 200 feet with heights being called out by the AMO from the radar altimeter until it went off scale around 700 feet when the second pilot standing between the pilot and the AMO took over giving heights from the radio altimeter, which was much more precise at low levels. Not wishing to hang about too long at that height, the AMO rapidly read his instruments and the climb began. This part of the trip was more comfortable than the estimated 50 feet of earlier years, but it was still not easy for the pilots to hold a precise height this close to the wintry North Atlantic Sea; I recall one occasion, with a very senior, but out of practice pilot, when the trailing aerial vanished. Sea King pilots may snort at this point if they wish.
On the climb from 200 feet to 500 MB stops were made every 50 MB to measure temperatures. As already mentioned, precise, constant airspeed is very important for accurate temperature measurement and any fluctuation in the IAS necessitated a wait while instruments settled down. Fuel considerations and the crew's temper required that such delays were kept to a minimum. Close co-operation between Pilot, Engineer and AMO did the trick. As the required pressure level was approached, the AMO would call out, "200, 100, 50 feet, on height". The pilot would ease the aircraft from climb or descent to level flight while the engineer gradually adjusted the power. With a practised team the transition could be achieved with no change in the IAS allowing the AMOs to do their work rapidly and the sounding to be resumed without delay. This [unusual] teamwork with pilots co-operating with the rest of the crew, is probably similar to that found in 202's present work.
The dry and wet bulb psychrometer is not really suitable for measuring humidity at temperatures well below freezing - though it can be done with patience. For high altitude humidity the dew or frost point was measured using a Dobson-Brewer Frost Point Hygrometer, in which a sample of the outside air was cooled using a "slush" of alcohol and solid carbon dioxide until the Observer, looking through a lens, actually saw the dew or frost forming. In theory this operation was supposed to take about 20 minutes (the Meteorological Research Flight took rather longer), but, that being impractical for fuel reasons, the Bismuth Observers were rather proud of rarely taking more that three or four minutes even down to minus 40 degrees Celsius or lower. This instrument was usually mounted in the galley and operated by the second AMO nowadays we would say that the Met Observer/Cook was "multi skilled".
Probe tracks, H to N, were flown when a weather system beyond the reach of the triangles had to be investigated. They were designed to fit the prudent range of the Halifax. In this case the outward, low level leg was rather longer than a triangle one, but, on completion of the climb, a cruise descent to FL90 was made and the flights returned along its outward track at that height. 9000 feet is as close to the standard pressure level of 700 MB (9882 FT) as one is allowed to fly without oxygen.
A third type of track was BISMUTH O in the North Sea. This quite complicated, if short, track was flown at lower levels with a number of sounding ascents; it was used on occasions of Easterly airflows across the North Sea threatening the East Coast fighter bases with haar, fret or just clag.Flights were timed so that the climbs and descents were close to the international radio-sonde time of 1200 GMT and this was usually achieved with an 0800 take-off. So keen on this were some Captains that it became the practice to have the BBC Light Programme on the radio compass (well, what else would you use it for?) and for the wheels to leave the ground precisely on the sixth pip of the Greenwich time signal. As I recall, those same Captains expected a cup of coffee to be placed in their right hand within an infinitesimally short time of safety speed being called.
By the time that 202 Squadron was disbanded again in 1964, in addition to their other duties they had made over 4000 BISMUTH sorties entailing 40,000 hours of flying. On an individual basis, it was considered to be a great achievement if a Squadron member made 400 BISMUTH flights. This was certainly achieved by Master Pilot Radina and Master Signaler Stratton and would have been done by Flt Lt Ignatowski had the Squadron just lasted a few weeks longer. There are probably others (Flt Lt Dinnes?) and I apologize for not mentioning them. It is unlikely that modern management would approve the practice of marking the 400th BISMUTH by greeting the returning aircraft on the pan with a barrel of beer.
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