Those aircraft, such as the Boeing 737 and rival Airbus A320, make up 70 percent of all orders, with the heart of that demand found in the 160-seat range.There is no question the market is converging to this size, where network flexibility and cost efficiency meet, said Randy Tinseth, Boeing's commercial airplanes marketing vice president.Small, widebody planes in the 200- to 300-seat range are l