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 in the 990. This was still fewer passengers than the contemporary Boeing 707 (110 to 189) or Douglas DC-8 (105 to 173), although the 990 was 25–35 mph (40–56 km/h) faster than either in cruise. 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. They wanted a somewhat larger passenger capacity than the 880, which was the smallest of the first-generation U.S. jet airliners. The 990 began flight testing January 24, 1961. One change from the 880 was the large anti-shock bodies on the upper trailing edge of the wings to increase the critical Mach and reduce transonic drag. Like the 880, 990s incorporated a dorsal "raceway" added to the top of the fuselage to house the two ADF antennas and one VHF antenna. When the major airlines retired their Convair 990s, they found a second life on charter airlines. Spantax of Spain had a large fleet until the mid-1980s and so did Denver Ports of Call. In 1967, Alaska Airlines purchased Convair 990 PP-VJE from Varig, and operated it as N987AS in scheduled airline service until 1975. A total of 37 aircraft were produced. For more information, click here.