To comply with the approved airline Operations Manual in a twin-engine aircraft (1 h 45 min flight on 1 engine at an air speed of 420 KT to reach the alternate aerodromes in still air conditions), a pilot has to choose an ATC route, in Minimum Navigation Performance Specification area, while at the same time taking the shortest possible time.Given that the three alternate aerodromes taken into account are SHANNON, SANTA MARIA, ST JOHN TORBAY, the track to be chosen between PARIS and WASHINGTON will be: