It was a stretched version of its earlier Convair 880 produced in response to a request from American Airlines: the 990 was lengthened by 10 ft (3.0 m), which increased the number of passengers from between 88 and 110 in the 880 to between 96 and 121.

American Airlines asked Convair to design an aircraft for coast-to-coast flights, able to fly nonstop from New York City to Los Angeles against the wind.

[2] One change from the 880 was the large anti-shock bodies on the upper trailing edge of the wings, to increase the critical Mach by reducing transonic drag.

[5] Despite the modifications from the basic 880 and those in response to drag problems in testing, the aircraft never lived up to its promise of coast-to-coast nonstop capability from JFK to LAX.

A drag reduction program was instituted during which streamlining of the engine pylon/wing interface and addition of nacelle fairings achieved 0.89 Mn.

[9] In contrast, a modern Boeing 737 MAX 8 typically carries 162 passengers and burns 4,460 lb (2.02 t) per hour at Mach 0.78 (450 kn; 833 km/h) at sub-optimal parameters.

Scandinavian Airlines (SAS) also operated 990A Coronados on their long-haul schedules to Tokyo and other destinations in the Far East and also to South America and Africa.

By the time the assembly line shut down in 1963, only 37 990s had been produced, bringing General Dynamics' entire production of commercial jet airliners to 102 airframes.