Before starting this discussion I must apologise to the many people here who have considerably more experience of civil instrument flying in helicopters than I. However, the major part of this talk is merely a history of the certification of the Bölkow BO. 105 for instrument flying. We all realise that flying under IFR is not the all weather flying quoted in the title of today's symposium however for the light helicopter it is a very significant step forward. My personal experience of this programme is very limited, and indeed the Civil Aviation Authority knows more of both the design philosophy behind the IF installation and the actual tests conducted than I. I intend to give a short historical description of the problems encountered and envisaged in getting the certification, followed by the equipment required in the aircraft and the use that an operator could make of a machine of this size when IF equipped.