TK period.
I'm not certain, but I think the TK time chart was the one produced by M Guimbal for his Cabri G2 publicity, being the occasion I completed an air test for an article for LOOP circa 201O ish. I've used the acronym ever since, but no doubt it is one of those terms that has been in existence for many years but largely forgotten.
New subject: AAD air show at SA Air Force base Waterkloof last week ... I completed a series of MD 530F displays at the show and wonder if any PP'rs were there for a critique. The show was of Farnborough proportions and even featured the first public flight of the Paramount Group's New AHRLAC multi role prototype.
Take care all. Dennis K.