Air Transport World

Twins across the water standards near adoption. (standards for certifying twin-engined airliners for long overwater flights)

Washington--The standards to be used in certifying twin-engine airliners for long overwater flights and conducting such operations are, for the most part, set. Although comments on the proposed International Civil Aviation Organization guidelines and Federal Aviation Administration's recently released draft advisory circular (AC) remain to be considered, little change of substance is expected.

Included in the standards are target levels of engine and system reliability, greater aircraft system redundancy requirements, and more strict operating procedures. Already Boeing is building new 767ERs to meet the tougher standards, and Airbus says its A310-300 meets the requirements as it is.

A Boeing official predicts that two or three airlines will be flying the North Atlantic in twins by early 1985, joining the occasional El Al 767 now flying nonstop Montreal-Tel Aviv. The age of the transatlantic twin is upon us.

The standards contained in the draft AC and ICAO proposals are similar, the result of a two-year series of talks and meetings, largely centered in ICAO, that included participation of nearly every major player in the world air transport game. Participating in the process were the certification authorities from the U.S., U.K., France and West Germany; manufacturers Boeing, Airbus, McDonnell Douglas, Rolls-Royce, Pratt & Whitney and General Electric; plus the International Federation of Air Line Pilots Associations and IATA.

It is a consequence of this wide-ranging participation that there is expected little serious objection to the new standards. Doubtless there will be a good deal of fine-tuning, but the major points already have met wide-spread agreement.

However, although the content of the proposals is not disputed, there is a degree of rancor in some circles about the process FAA is using to establish and administer the standards. Also, there are disputes about the rules to be used in calculating engine reliability, and assertions by manufacturers that some of the experience requirements are too conservative, even to the point of inhibiting technical advancement. No set limits

The FAA standards will allow flights to be made on routes that take aircraft as far as wo hours away from alternate airports, but it also opens the door for even greater distances after more experience is gained in long-range twin operations. The ICAO proposed standards offer no set limits, but instead offer a sliding scale that relates allowed diversion times to proven engine reliability rates--the more reliable the engine, the greater is the allowed distance to an alternate airport. …

Log in to your account to read this article – and millions more.