American will use mostly twin-engine planes on the new routes, while Eastern used less fuel-efficient three-engine aircraft.

"The higher the oil price, the greater the demand for more fuel-efficient aircraft," said Mr. Humbert.

This was intended as a highly fuel-efficient aircraft employing new technologies, but it was cancelled when the price of oil dropped during the 1980s.

Technology The race to develop stronger, lighter materials that will make aircraft more sturdy and more fuel-efficient is intensifying.

Plans for an acquisition of more fuel-efficient aircraft of the Boeing 747-400 type could not be realized.

In addition to traffic growth, high fuel prices are pushing carriers to buy new, more fuel-efficient aircraft.

These fuel-efficient, 180-seater aircraft are an upgraded version of the Airbus A320.

There's no problem with that But the carriers now want extremely fuel-efficient aircraft.

"It is one of the most fuel-efficient aircraft in service today," Mr. Schleh said.

Billed as one of the world's most fuel-efficient aircraft, it claims to offer better air quality and a smoother, quieter flight.