This paper concentrates on helicopter operations in the London area. There are of course, other fields of helicopter operations—most topically those to and from oil rigs in the North Sea—but times does not permit consideration of them on this occasion. I shall first then, attempt to set the scene by describing the layout of the controlled airspace which contains the helicopter route system for the London area.

This consists of the London Control Zone (Fig. 1), centered on London (Heathrow) Airport and it measures approximately 26 nm east to west and 16nm north to south. Its vertical extent is from ground level to FL 110 (11 000 ft approximately). This Zone is surrounded by the London Terminal Control Area, the base of which varies between 1500 ft and 2500 ft with a top limit of FL 250 (25 000 ft).