With no other civil traffic operating at its cruising altitude of about 56,000 ft (17,000 m), Concorde had exclusive use of dedicated oceanic airways, or "tracks", separate from the North Atlantic Tracks, the routes used by other aircraft to cross the Atlantic. Due to the significantly less variable nature of high altitude winds compared to those at standard cruising altitudes, these dedicated SST tracks had fixed co-ordinates, unlike the standard routes at lower altitudes, whose co-ordinates are replotted twice daily based on forecast weather patterns (jetstreams).[138] Concorde would also be cleared in a 15,000-foot (4,570 m) block, allowing for a slow climb from 45,000 to 60,000 ft (14,000 to 18,000 m) during the oceanic crossing as the fuel load gradually decreased.[139] In regular service, Concorde employed an efficient cruise-climb flight profile following take-off.[140]