A prototype of the single-engine jet to be used for the flight

London, Feb. 27: All being well, GlobalFlyer, an attempt at flying solo 25,000 miles round the world without refuelling, should pass ?over or near? Calcutta towards the end of week.

Whether passers-by in Shyambazar will be able to spot the 114 ft by 44 ft single engine jet remains to be seen since the plane is expected to cruise at 45,000 ft, but on a clear day, with a good pair of binoculars, anything is possible, predicts an over-optimistic mission control in America.

The trimaran-like contraption is being flown by American adventurer Steve Fossett, 60, with boss of Virgin Atlantic, Sir Richard Branson, 54, acting as stand-in pilot prepared to step in if Fossett has to pull out for any reason.

Fossett is perhaps the ultimate Aviator going for a new world record, just as the film of the same name prepares for glory at the Oscar ceremony in Los Angeles.

Forget Phileas Fogg?s Round the World in 80 Days. GlobalFlyer is planning to do the trip in 80 hours.

This is why it is taking off with 18,000 lbs of fuel, which will account for 80 per cent of the aircraft weight at the start. The length of available runway at Salina, a little known city in the US state of Kansas, where the epic voyage is due to begin 2.30 am IST on Friday, will have to be, at least, 9,000 ft.

Even so, fully laden, the wing tips will be barely 18 inches off the ground.

?The most dangerous aspect of the flight is take-off,? warned Fossett.

GlobalFlyer is expecting to encounter a great deal of turbulence as it climbs to its cruising height of 45,000 ft which will not be till Fossett reaches Egypt or thereabouts.

His route will take him across the Atlantic Ocean to the UK and then south to the Mediterranean and through the Persian Gulf to Pakistan, India, China and Japan. From there he will cross the Pacific and head back to the launch destination.

During the flight, GlobalFlyer could cross over or near Montreal, Gander, London, Paris, Rome, Cairo, Bahrain, Karachi, Calcutta, Shanghai, Tokyo, Honolulu and Los Angeles.

?We think we?ve done our homework,? said Fossett, who has achieved several ballooning and gliding records. ?All of our indications from flying it at lower weights have been extrapolated; we think we understand the performance of the airplane well enough.?

?This plane changes a lot while it is flying,? explained Fossett, who will have to cope with severe sleep deprivation. ?It?s a heavy plane when I start and very light when I finish. I have to do a lot of fuel distribution ? making sure the airplane stays in balance all the time. It?s an experimental airplane; there?re more things that have to be monitored, so I would rather not sleep so I can stay on top of things.?

An aircraft called Voyager, similar in design to GlobalFlyer, flew round the world non-stop in 1987 but that trip required two pilots and 9 days, 3 minutes and 44 seconds. This flight nearly doubled the previous distance record set in 1962 by a USAF/Boeing B-52H.

For the Virgin Atlantic, GlobalFlyer and its pilot to set a world record for the first solo, non-stop, non-refuelled circumnavigation of the world, they will have to follow a strict set of rules laid down by the governing body of aviation record attempts, the Federation Aeronautique Internationale.

According to the Guinness Book of World Records, the fact that it?s a ?first? doesn?t in itself make it a record, said a Virgin Atlantic spokesperson. ?Therefore, Steve will have to do the circumnavigation faster and higher than any other in order to take an official record.?

The spokesperson added: ?The FAI?s rules state that a record attempt like this must start and finish at the same airfield and cross all meridians of the globe. What?s more the course must not be less than the very precise figure of 36,787.559 km (around 23,000 miles) which is equal in length to the Tropic of Cancer.?

Branson, who has given ?1 million towards the project, is hoping to be up in the air part of the time to cheer Fossett on.

Branson admitted: ?Half of me particularly wants Steve to stay well but there is a bit of me that would love to do it.?