I am investigating the details of my grandfathers RAF career through his 3 tours 1941-1945, and have come across a segment that I cannot find any details on. Between first and second tours, he was at 16 OTU in Upper Heyford as W/T instructor for several months, and was then detached to what is described as "Special Navigation Flight" at Bassinbourn as part of No. 11 OTU in July and then immediately on to Chipping Warden as part of No. 12 OTU, and still referred to as "Special Navigation Flight" in the log book. During that time he seems to have been training on something, in Wellingtons. But I cant find out what it was that he was training? Was this one of the newer "hi-tech" navigation or tracking methods?
In August he returned to Upper Heyford to his regular OTU posting, and eventually back to operations for second tour.

Can anybody help me with information about what he would have trained on in Wellingtons in the middle of 1942 at Bassinbourn and Chipping Warden?
Chris Smith