I’ve been away for a few days, so my belated thanks for all the useful input.

During the interim I’ve discovered a little more from AP1134 The Second World War 1939-1945: Meteorology, a 1954 AHB publication.

The establishment of 1401 Met Flight was increased by two ‘F’ type Spitfires (I’m quoting) during August 1941, for deep penetration over enemy territory. The sorties were to be flown at around 30000 ft, over a total distance of no more than 1000 miles.

The increased establishment was apparently a paper one since, as I noted earlier, this first PAMPA sortie was not flown until 7 November 1941.

Because the aircraft failed to return, the flights were discontinued until a larger establishment and experienced personnel could be provided.

Wish I’d found this before asking the question, but I think it confirms your calculations, Sycamore.

Perhaps I’m reading too much into it, but the reference to experienced personnel, could be taken to imply the pilot lacked sufficient experience in navigation for such a long sortie, and departed from the planned track. At least that would explain why he ended up at Beachy Head.

I’ve l looked at the 521 Sqn ORB from the date it formed from 1401 Met Flight (1 August 1942) until October 1942. It was using Mk VD Spitfires for PAMPAs at the time, the last Spitfire PAMPA being flown by R6905 on 10 Sept. During that period most sorties were less than 3 hours, four were over 3 hours and one lasted 4 hours and 5 minutes.

Edgar

The idea that the jetstream was a new met phenomena raises its head from time to time. There are various claims as to who invented the term, and when; but ‘jetstream’ really came into popular usage after WW2, to describe a ribbon of fast-moving air at high level. The phenomena had actually been identified as early as the 1870s by meteorologists tracking elements of cirrus cloud (circa 30000 ft), so it was nothing new.

Today winds are considered to reach ‘jet’ strength when they exceed 75 mph (or it was in my day), but obviously they can reach very much greater values.

Consequently, in the case of P9550, the forecast wind of 290/80 mph was, technically a ‘jet’.