Air Transport World

Overwater twinjet era begins.

Existing transatlantic twinjet operations are, in many ways, experiments by manufacturers, regulators and operators with two desired results--safety and economy. The economics of the issue largely are dependent upon the safety of the operation, for the more technically proficient and reliable the service the fewer economy-destroying enroute diversions there will be.

No one disputes the economic advantages of a new-generation twin over a trijet on a correctly sized route. It is the safety of the operation that is the major point to be proved by the current services. And while all major players in the game believe the current rules provide a conservative level of safety in the ultimate crash-into-the-sea sense, the real test will be whether diversions can be limited and dispatch reliability maintained under the stricter rules that apply.

If the desired levels of service reliability and safety can be maintained in transatlantic operations--the proving ground for long-haul twinjet operations--the existing services will be considered the progenitors of a major advance in airline technical and marketing flexibility.

Although recently published FAA rules restrict operations to routes that stay within 120 min. of suitable diversion airports, the regulators are anticipating the day when restrictions are limited simply to extensive preparation of aircraft, crew and procedures.

FAA optimistic

"From a type design point of view there is no limit to the amount of time (an approved extended-range twinjet) can support safe flight and landing on one engine," said the FAA official largely responsible for writing the new rules. "In the future, is the operational experience is as goodd as we hope, (such operations) can go unconstrained, or at least more than 120 minutes." This is the judgment of Jerald Davis, manager of FAA's flight technology programs branch in the Office of Flight Operations.

Twinjet transatlantic scheduled passenger service has arrived. Barring glitches, the existing scheduled TWA and Air Canada transatlantic services, plus the occasional EI AI operation, are just the meager beginnings of a trend fed by the increasing drift away from international gateways and the growing popularity of point-to-point international flights.

Popularity does not always translate into acceptable load factors on Boeing 747s, McDonnell Douglas DC-10s or Lockheed L-1011s operated with sufficient frequency. These airplanes cannot replace the largely discarded Boeing 707s or short-body McDonnell Douglas DC-8s on a one-to-one basis. A Boeing 767ER or Airbus A310-300, on the other hand, is a pretty good match for many thin transoceanic routes. The bigger widebodies no doubt will remain supreme on the international trunk routes. …

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