A mate of mine at Britannia who had known Bill in the arrows said his eyesight was always suspect.
A bit of thread drift.... Bill's eyesight was just fine. I flew to Farnborough as a passenger on that Buffalo, and I rode jump seat during the show two days before the accident. I later flew a hundred or so hours ferrying with him after he left DHC. The Buffalo accident had other factors. Bill was not blameless, but it wasn't all him either...
Pardon the drift, back to the Learjet discussion....