The King Air is a sprightly performer (well, sometimes!) and I know of a 90 that's operated off a private grass strip which is around 800m long.
I can believe it. The Cega King Airs use surprisingly little of Goodwood's longest runway (the 1280m 14/32) and i'm fairly sure they use the 850m runway 24 in conditions that would make their usual choice of 14/32 a bit too 'interesting'.
They do make a good plough when Goodwood is at its most soggy, but they usually head off to Lee on Solent at that point. Sadly not an option for the rest of us
