It is, literally, an overview. It's a piece of contemporary jargon, but older than you might think. Its original source seems to be the real 'helicopter views' that feature on television news in America, where police-car chases provide a regular part of the programming. The earliest published example MT has been able to find of the phrase being used in the modern sense was in the New York Times in 1981, in an article about a famous architect accused of taking 'a helicopter view' of housing, after building an estate of new homes without consulting any of its likely residents. That's the kind of mistake you are liable to make if you look at everything from up in the sky and never from ground level: not for nothing is the 'helicopter view' also known as the '10,000 ft view'. The air is clear up there, but sooner or later you have to come down. Happy landings!