A non-stop flight is a flight by an aircraft with no intermediate stops.
An ultra long-haul non-stop flight is a flight by a commercially operated airliner without any scheduled intermediate stop of any kind and route length using the higher end of the airliners' range. These flights usually follow a great circle route, often passing over polar regions.
From 1943 to 1945 Qantas operated a weekly Consolidated PBY Catalina 5,650-kilometre (3,050 nmi) return flight from Western Australia to then Ceylon with average flight times of 27 h, the Double Sunrise service. On 1–2 October 1957 a Trans World Airlines Lockheed L-1649 Starliner flew the inaugural 8,640-kilometre (4,670 nmi) London–San Francisco polar route in 23 h 19 min. The L-1649A was the last of the Constellation series, and the ultimate piston-engine airliner in terms of range and endurance.
In June 1961 El Al established a new record for the world’s longest non-stop commercial flight at 9,270 kilometres (5,010 nmi) from New York to Tel Aviv with a Boeing 707 flown in 9 hours 33 minutes, after trying a Bristol Britannia in December 1957. In August 1967, Aerolineas Argentinas established their non-stop Boeing 707 service on 10,062 kilometres (5,433 nmi) between Madrid and Buenos Aires with a flight time of 12 h.