THE Boeing 747 celebrated the 25th anniversary of its first revenue flight at the weekend, with the jumbo still holding claim to being the largest commercial aircraft in the world. The first flight, on January 21, 1970, carried 324 passengers from New York to London. The airline, Pan American World Airways, is now defunct. But the 747 is still much alive, with today's 747-400 model far different from its parent. Adjusted for inflation, the Boeing group has delivered US$125 billion worth of 747s since the first went into service. Sales to airlines outside the United States total nearly $102 billion, with nearly 93 per cent of all 747 sales in the past five years to customers overseas. A total of 83 operators fly 1,046 of the 747s today, with orders still coming in, and more than 1.5 billion passengers have flown on the jumbo aircraft since Pan Am's first flight. Manufactured from about six million parts, the 747 was expected only to be in service for 20 years, but became one of America's leading export products. Last year, the jumbo programme provided an estimated 80,000 full-time jobs - 32,800 at Boeing, 36,800 at other US manufacturing companies, and 10,400 at suppliers around the world. Today's 747-400 typically carries 420 passengers in a three-class configuration, and has a range of almost 13,000 km. Only two officers are now required in the cockpit as computers replaced the navigator, and the 971 lights, gauges and switches of the first 747 have been reduced to 365.