Re. the Tenerife incident, that is why en-route clearances are now passed as "After departure..."
Back on thread...from someone who has only had 20 hrs flying in light aircraft, I find it most difficult to pick out grey aircraft against a grey background, how about compulsory flourescent paint schemes? Or is VFR maybe archaic in todays high density fast (compared to the old days anyway) traffic situation.
As for the military's suggestion don't fly between 1000' and 2000' that's a non-starter for VFR flight most days in the UK. Below 1000' and you're dicing with the fast jet jockeys and Rule 5, above 2000' you're usually skirting the cloud base.