AP, you would need a timeline for IFR as it was known in the 50s and 60s. If the Valiants were not yet operating as tankers then the Trial was probably so determine flight handling characteristics, flow transfer.
The 'A' may have related to a follow-on trial either with different or modified baskets etc.
I know that in 1964 when I did the receiver course that they were still developing night refuelling. One 'fix' was to strap bicycle dynamos driven by propellers to illuminate the basket.
*Ping!
Above and below might have referred to the position of the aircraft but not actually hooking up as giver or receiver.
Last edited by Pontius Navigator; 10th Dec 2012 at 17:10.