THE Boeing Corp will continue studying the development of a new supersonic passenger aircraft for use in the next century after finding no insurmountable problems to force it to be shelved. The US-based manufacturer's sales director for Australia and the Pacific Islands, Lane Soholt, conceded at an Ansett Australia transport conference yesterday that a high speed civil transport (HSCT) would be expensive and would pose environmental concerns. But, Mr Soholt said, joint development by manufacturers and adequate sales would allow the hurdles to be overcome. 'We see a potential market that certainly justifies continued study. Clearly, we don't see any of the technical or economic challenges as being insurmountable, or we would have concluded our research,' he said. 'The key to the ultimate decision will not rest with us, the manufacturers, but with the market. The airlines will want an aircraft capable of generating sufficient revenue to cover operating costs and return a profit without the need for much - if any - surcharge in fares.' The HSCT under preliminary study would be able to carry between 250 and 300 passengers, and would travel at about mach 2.5 - more than 2,500 kilometres an hour, or 21/2 times the speed of sound. A Boeing 747-400, in comparison, travels at about mach 0.85 while a Concorde - the only supersonic passenger aircraft flying today - cruises at about mach 2.2. The aircraft, because of its sonic boom, would have to be held back from flying supersonic within 50 nautical miles of any coastline, Mr Soholt said. Studies have also shown that passengers would not welcome faster flying times if surcharges were more than 20 per cent above those for current subsonic flights. About 500 city pairs had been identified in which the aircraft could be used. Boeing is studying the feasibility of an HSCT with the American space agency NASA, rival aircraft maker McDonnell Douglas and engine manufacturers General Electric and Pratt & Whitney, as well as with European and Japanese aerospace concerns. Mr Soholt said the technology to begin formal development would be ready by 2005. The aircraft could be flying by 2010.