chinook240
A climb into icing conditions is a brave decision, but it would have to be balanced against the alternative risks and the aircraft's known record in icing conditions ie did a previous mark have a clearance down to -6 deg and had there been changes made that would affect its performance.
It would appear the Boscombe Down test pilots were not happy to simply 'read across' with respect to the icing limitations of the Mk1 to the Mk2?
Maybe that's why you would regard such a decision by Flt Lts Tapper and Cook to be 'brave'? It contravened the rules.
FWIW, I, along with the Station Commander RAF Odiham, find that the 'guesstimates' used to propose the
possible theory of a cruise climb, produce a combination of parameters which are unrecognisable as a chinook technique!
Let right be done.