Passengers could be flying across the oceans on jet airliners with two engines, instead of with three or four, in the not-too-distant future, according to airline and aircraft officials.

"With today's engine reliability, there's no reason why twin-engine aircraft can't operate transpacific and transatlantic," said O.M. (Rusty) Roetman, vice president of international sales of the Boeing Commercial Airplane Co.

Until now, the idea of twin-engine commercial aircraft on transoceanic flights hasn't been considered seriously, even though twin-engine business jets make transatlantic crossings all the time. But now, Boeing and Airbus Industrie are producing brand-new, two-engine commercial planes that are capable of making the crossings, and will be able to do so at a lower cost per seat-mile than some of the planes they would replace.

Commercial flights by twin jets over Pacific and most Atlantic routes would require changes in international flight rules. An International Civil Aviation Organization rule currently limits twin-engine airplanes to routes on which they are never more than 90 minutes away -- at cruising altitude -- from a suitable airport.

Federal Aviation Administration regulations are even more restrictive, requiring a twin-engine plane to be no further than 60 minutes flying time -- at cruising speed on one engine -- from an airport. Eastern Airlines has an exemption that lets it operate its twin-jet Airbus A300 up to 75 minutes from an airport, allowing the plane to be used on routes from New York into the Caribbean. Air Florida has a similar exemption.

According to former FAA administrator Langhorne Bond, the FAA's 60-minute rule means in practice that an aircraft must be within about 460 miles of an airport at all times. This eliminates the shortest routes across the Atlantic, as well as twin-jet flying between the West Coast and Hawaii, and on routes in the North Pacific.

Citing the technical progress that has been made in aircraft engines since the FAA rules were set almost 30 years ago in the piston-engine era, Bond last month urged a re-evaluation of over-water flying by twin jets in a speech to the National Association of State Aviation Officials in New Orleans.

A spokesman for the FAA said that the agency has been reviewing the background and history of the rule. "We are looking into it, but have reached no conclusions," he said.

The new twin jets on display at the Farnborough Air Show in England last month demonstrated their long-range capabilities, Boeing's wide-body 767 this summer broke what is believed to be a nonstop distance record for a twin-jet airliner when it flew nonstop from Oslo to Seattle, a distance of 4,994 miles, in nine hours and 50 minutes. The narrow-body Boeing 757 flew nonstop from Tokyo to Seattle, a distance of 4,914 miles, in nine hours and seven minutes.

The Airbus wide-body A310 this summer flew nonstop between Kuwait and Singapore, a distance of about 4,154 miles, in eight hours and 40 minutes.

Both Boeing planes were flown nonstop from North America to London for the Farnborough show. "There's really no reason not to," said Eastern Airlines Chairman and President Frank Borman aboard the 757 that will be Eastern's after it is approved by the FAA for commercial service. "I've got thousands of hours behind a single-engine plane," the pilot and former astronaut said.

"On a strict technical basis, we agree with Boeing," said Pierre G. Pailleret, senior vice president-marketing for Airbus. "The safety requirements are more than met.

"The two questions that remain are 1) will the civil aviation authorities change the regulations, and 2) will Mrs. Smith go on a twin from New York to Paris?" Pailleret said. Mrs. Smith might have balked 10 years ago, but she's already going from Paris to Dakar on a twin, and will accept a transatlantic flight on a twin, he predicted.

L. Edwin Smart, chairman and president of Trans World Corp., agreed. "We weren't uncomfortable at all with the idea of the two-engine jet," he said after a flight to London with his family on the 767. "Our technical people, who are always conservative, had serious doubts about the three-engine L1011 flying transatlantic, and it's doing just fine," he said.