When I first came to the Falklands, flying S61 for Bristow on the military contract, one of the crews landed on the point at Goose Green one day. The crew noticed that the minefield signs seemed to have faded badly, with no red paint or writing, just a silvery colour . . .
They took off again (with fingers crossed I guess, as I think mines detonate when the load comes off them?), and re-landed, on the safe side of the fence !
(After the event, a minefield sign was hung in the Bristow bar, suitably annotated on the reverse “You have just landed in a minefield” )