Airbus plans son of Concorde Jonathan Leake, Science Correspondent BARELY two years since the last Concordes were retired, Airbus, the European aircraft consortium, is looking at plans for a new generation of supersonic passenger jets. The manufacturer, in which Britain?s BAE Systems is a partner, is drawing up designs for a 250-seat plane with a range of up to 6,000 miles that could reach speeds approaching 1,500mph. It believes that rapid growth in the aviation market means that by 2050 there could be demand for supersonic travel on hundreds of long-haul routes. Corinne Marizy, an Airbus researcher, told a conference at Cambridge University last week that by 2050 supersonic travel could account for 10% to 20% of flights. Airbus?s design is one of a number of blueprints being drawn up around the world for supersonic jets, the first of which Marizy said could be in service by 2015. By 2025 the market would be growing fast, she added. Marizy and Airbus have been taking part in a Europe-wide study to measure the impact that a fleet of supersonic aircraft might have on the atmosphere. There have been fears that because they fly much higher than conventional aircraft, the jets might damage the stratosphere by releasing soot, carbon dioxide and water vapour into air that is currently almost unaffected by human activities. At the conference Marizy conceded that the stratosphere would be affected, mainly by an increase in its water vapour content. The stratosphere is extremely dry and at that level water vapour behaves like a greenhouse gas, helping to warm the earth by reflecting back heat that would otherwise escape into space. She pointed out, however, that the warming effect was likely to be quite small compared with that caused by emissions from conventional aircraft. Her comments come amid a worldwide resurgence of interest in supersonic travel. In the next few weeks Japan is due to launch an arrow-shaped plane at twice the speed of sound high over the Australian outback. The aircraft ? a Franco-Japanese design ? is an unmanned model but the aim is to use it to build a 300-seat aircraft that could reach service by 2015. Its engine has already been tested to Mach 5.5, or 3,700mph, which would bring New York within an hour?s flight of Heathrow. The most likely prospect for a new supersonic passenger plane is not a commercial airliner but a business jet aimed at a segment of the flying public. The aircraft makers Lockheed Martin, Northrop Grumman, Dassault, Gulfstream, and Sukhoi have all announced plans for such planes. Professor Peter Haynes, acting director of the Institute of Aviation, based at Cambridge University, said the fall in the price of air travel at a time of rising incomes could create a lucrative market for supersonic flights among ordinary travellers as well as the rich. Aviation is coming under increasing scrutiny for its impact on global warming. In Britain the government predicts that air passenger numbers will rise from 180m to 475m by 2030. Last week Elliot Morley, the environment minister, said that he wanted aviation to be included in international emissions agreements. Roger EWROPS