British Airways was recently granted permission for its fleet of Boeing 747-400 and 767 aircraft to operate using automatic landing systems in Category IIIB conditions; that is, decision height lower than 50 ft and a runway visual range of less than 200 m. This development might lead some people to think that the weather is no longer a significant factor in aviation operations. However, while these developments are taking place one sees reports such as ‘departure delays are still on the increase’; ‘poor weather slowed airport operations’; ‘BA flight from Singapore delayed by strong winds was five minutes from declaring an emergency’; ‘heavy rain might reduce wing lift when an airliner most needs it’. These reports confirm the realistic state of affairs that the weather, despite the introduction of modern avionics on board the aircraft, and automated instrumentation on the ground assisting aerodrome operations, is still a vital part of aircraft operations decision-making, affecting the safety and efficiency of flying.