 Joined with Pan Am's request was Iran Air; their joint interest was for a high capacity airliner capable of covering Pan Am's New York–Middle Eastern routes and Iran Air's planned New York-Tehran route (New York to Tehran was the longest non-stop commercial flight in the world for a short time).The aircraft was launched with Pan Am's first order in 1973 and the first example delivered in 1976.A shorter derivative of the , the SP was developed to target two market requirements.