New plane design set to boost safety

Improved safety and an end to flight delays could be on the cards if an experimental aircraft improvement developed by Boeing proves its worth in full-scale trials.

Boeing, the world's largest aircraft manufacturer, has been testing a new device which reduces the strength of powerful air currents which can cause turbulence and even lead other planes to crash in the wake of a large aircraft.

The system has already been so successful in wind tunnel tests with models that Boeing is currently moving to patent the device - which can be fitted to existing aircraft. The company is now working towards trials on full-sized aircraft, using a Boeing 757.

Tackling the problem of the air currents - known as wing-tip vortices - has the potential to eradicate airport delays, improve safety and even reduce air fares.

At present, aircraft have to be kept between 2.5 and three miles apart because of the strong air currents which emanate from their wing tips. Air currents produced by the wings - especially of a larger plane - can disturb aircraft landing immediately behind.

In extreme cases, when a large airliner has been followed by a smaller aircraft, serious accidents have occurred. Boeing's 757 had to be reclassified as a heavy aircraft five years ago after it was found to have unusually heavy trailing vortices. This came to light after a business jet following a Boeing 757 crashed in the US the previous year.

Many airline passengers have experienced the problem to a lesser degree, but may have dismissed it as a particularly bumpy landing.

Boeing is keeping the new device under wraps until it secures a patent next month - but it works by enabling the wing-tip vortices to cancel each other out by colliding a short distance behind the aircraft.

According to Bob Kelly-Wickemeyer, Boeing's chief aerodynamics engineer, the device causes "a disturbance in the vortex network near the aircraft, so that the network collapses in upon itself within three nautical miles of the aircraft."

At present the only airport to operate to less stringent regulations is Heathrow, where the permitted distance between planes on landing can be reduced to 2.5 miles if conditions are right.

A spokeswoman for National Air Traffic Services, who provide air traffic control for 12 major UK airports including Heathrow, Edinburgh, Glasgow and Aberdeen, explained: "We have been reducing the distance at Heathrow now for a year but have only managed it on 10 days. We can only do it when conditions are gin-clear and there are no crosswinds."

She welcomed any new technique to cut congestion. "If Boeing does this and it is brought in by the US Federal Aviation Authority, we would follow suit. It might help get a few more aircraft into Heathrow, but it could be quite an advantage at other airports.

"At Gatwick, where the main business is holidays, there are always holding stacks in the summer - and most are full. If they can get the aircraft closer together, they will be able to get more planes in and then you might be able to get delays down."

The advantages of the new technique are expected to go well beyond safety. It will mean airports can handle more aircraft at peak periods, easing congestion and reducing delays.

Cost savings will be possible for airlines - who currently have to pay for fuel wasted while planes circle in holding patterns above busy airports, waiting to land. The device could also boost airport revenues, as more aircraft can be handled - and could help increase the number of landing slots at airports.

Airports such as Inverness and Guernsey have lost their direct flights to London Heathrow in recent years. Meanwhile, the new Dundee to London service introduced earlier this year by Scot Airways is having to fly to London City Airport because of the lack of space at Heathrow. Landing slots at Heathrow have changed hands for as much as #1 million recently.

Other airlines have reacted cautiously to the Boeing initiative. "We look forward to seeing what impact any new development might have on the airline," a spokesman for British Airways commented.

Industry insiders are surprised that the new invention has come from Boeing. Despite the company's reputation as a builder of reliable and ever larger aircraft, and the pioneer of pressurised airliners in 1940, it is not seen as a technical innovator. It prefers to develop existing designs - there are eight versions of the 737 - than produce new ones from scratch.

Boeing expects the device to be fitted to aircraft by 2005, and hopes that Airbus, its main rival, will buy a licence to incorporate the device on its designs.

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