This paper is an appreciation of the navigational problems encountered during a flight round the world in 1948, in a single-engined light aircraft. The route chosen (Fig. 2) covered nearly every type of flying weather in the world, from the perfect conditions of the Mediterranean in the summer to the severe climate of the Aleutian islands; navigation tests were provided by the overwater flights across the South China Sea (Hong Kong—Okinawa = 900 miles), the North Pacific (Chitose—Shemya = 1730 miles) and the North Atlantic.