I didn't write the headline. Walter DCA PARIS, May 13 (Reuters) - Boeing Co (BA), the world's biggest planemaker, has no plan to replace its mid-sized 757 and 767 jets in response to flagging sales, the chief of its commercial unit said on Monday. Boeing has booked only eight 757 sales in the last 15 months. Even before the September 11 hijackings hit demand for new planes, backlogs on several models were falling to worrying levels. Several industry sources in recent days said that the Chicago-based firm was now preparing its first all-new programme in a decade, with a more efficient replacement of the 757 the most likely scenario. "Right now we don't know of any plane we could make that's more efficient than the 757," Boeing's commercial jet chief Alan Mulally told reporters in Paris. "These airplanes are made for 30 to 40 years. Sometimes the economy will be down and you make less and sometimes it will be up and you'll make more." Mulally said for the moment the company's principle target remained the Sonic Cruiser, a futuristic plane whose delta wings would break with decades of conventional civil jet design and which would fly up to 20 percent faster than other airliners. "It's right on schedule," he said. "We're not looking for orders yet. We've got plenty of time to do it and get it right." He said the plane would probably come at the end of the decade. Recent speculation over the Sonic Cruiser has centred on how big it would need to be in order to be commercially viable. Mulally said it could be the same size as the 767, but would not compete with that model as the planes would not be used on the same routes due to their difference in speed. The September attacks hit air traffic and forced cash-strapped carriers to tear up expansion plans, leading Boeing to announce the firing of up to 30,000 employees at its civil arm. Though the company is trying to diversify beyond the volatile commercial jet business, that activity still accounts for 60 percent of its revenue and in the first quarter of 2002 it lost $1.25 billion, its first loss since 1997. Mulally reaffirmed a previous forecast that Boeing aimed to deliver 380 jets this year and between 275 and 300 next year. He would not be drawn on the number of orders he expects to book, but said that next year would represent the trough in demand. "We have turned the corner," he said. "By the end of the year we are assuming that the global economy will start to recover. The low point for deliveries will be next year... and we will then increase production again to more normal levels." ©2002 Reuters Limited.