The Anglo-French Concorde first flew in 1969 and entered commercial service in 1976. Concorde was the only Western supersonic airliner with sustained commercial service; the Tu-144 also operated commercially, albeit briefly. It carried 100 passengers at Mach 2.04—more than twice the speed of sound—at altitudes where the curvature of the Earth was visible. The delta-wing design with ogee planform was a compromise between supersonic efficiency and low-speed handling. Twenty were built. The only fatal accident occurred on July 25, 2000, when Air France Flight 4590 crashed shortly after takeoff from Paris, killing 113 people. The fleet was grounded for modifications, returned to service in 2001, and retired in 2003. The economics never worked: high fuel consumption, limited routes over water to avoid sonic booms, and maintenance costs that consumed any profit. But for those who flew it, Concorde was incomparable.