"The problem is all the unknowns that are being introduced and then explained away as if there is no problem," said Vince Weldon, a former Boeing engineer, in an interview to be broadcast as part of Rather's report. Weldon compares a recent crash in a standard aluminum airliner where the dented but intact fuselage kept fire at bay and allowed the passengers to leave the aircraft alive.

"With a composite airframe, the fuselage would not crumple, it would shatter ... that shattered hole would be there for the fire that's going into the airplane," Weldon says in the interview. "Instead of everyone getting out, it would be a far less positive result." Weldon says he was fired by Boeing after a 46-year career because of his persistent complaints about the design of the 787. He claims he represents the view of others at Boeing who were afraid to speak out. Boeing, which did not provide officials for on-camera interviews in Rather's report, said today Weldon's claims were not valid and the plane would not fly if it is not safe.

"We've looked at Mr Weldon's claims. We've had technical committees review them. We do an exceptional amount of testing," said Lori Gunter, a spokeswoman for Boeing's commercial aircraft unit. "Absolutely, these materials are safe.

They are tested, they will be certified." She said the US Federal Aviation Administration (FAA) must find the 787 to be as crashworthy as aluminum aircraft, and the plane was doing well in those tests so far. She declined to comment on the circumstances of Weldon's departure from Boeing. Boeing's lightweight, fuel-efficient 787, which has become its most successful aircraft launch ever, is set for its first test flight between mid-November and mid-December after a three month delay due to a shortage of bolts and problems programming the flight control software.

The first 787 is due to be delivered to Japan's All Nippon Airways in May next year, meaning it will have at most six months of flight tests, much shorter than previous jetliner programs. Boeing's rival Airbus, owned by European aerospace company EADS, is also working on a composite fuselage for its new A350 jet, but it is some years behind Boeing in the design and production process.

In Rather's report, Weldon and other experts also argue that the carbon-composite fuselage would not survive a lightning strike as well as aluminum, would emit toxic fumes when burning, and could easily be damaged without any visible sign. Weldon says Boeing was misrepresenting to airlines the ease of maintenance on carbon fuselage aircraft. The report cites experts referring to Airbus planes that had carbon parts with problems that were not easily visible. Rather's report also includes aviation experts who see little or no problem with the 787.

"I'm excited to ride on the 787. I'm excited to fly in composite aircraft," says Joseph Rakow, an engineer at consulting company Exponent Inc, in an interview in the report. Todd Wissing, a commercial pilot, says he would fly the 787 as long as the composite materials are rigorously tested. "We put safety as our top priority," says Wissing in the report. "We use the 21st Century inspection methods with these new materials. Then we have complete confidence that we can get in that airplane with our passengers and go fly because that's what we can do."

The report by former CBS News anchor Dan Rather is the latest edition of Dan Rather Reports, broadcast on HDNet, a subscription-only television channel that about four million Americans are able to view. Last year Rather left CBS after a scandal over his reporting on US President George W Bush's military record. Reuters