35 years ago, on 1 February 1985, TWA flight 810 departed Boston for Paris on the first reveue flight operated under 120-minute ETOPS (ETOPS-120) rules using a Boeing 767-200 upgraded to ETOPS standards, a milestone which led to the use of twin-engine jetliners on nearly all long-distance flights today. The fuel burn on TWA 810 was 7,000 lbs per hour less than that of a Lockheed L-1011 TriStar flying the same mission, leading TWA to spend $2.6 million per aircraft to retrofit each of their 767-200s to meet ETOPS-120 requirements.
El Al had been flying the 767-200 trans-Atlantic between Tel Aviv and Montréal for nearly ten months but not under ETOPS rules, requiring a longer routing so as to stay within 60 minutes of a suitable alternate airport. Prior to that, Airbus A300 operators had been flying that first widebody twin-jet across the North Atlantic, the Bay of Bengal, and the Indian Ocean since 1976 under ICAO rules for 90-minute ETOPS.
Today's Featured Map shows the great-circle path from Boston to Paris (winds aloft may have led to a different path) plus ranges at single-engine speeds for 120 minutes from diversion airports at Gander and Reykjavík plus, in green, possible mid-Atlantic alternates at either Kangerlussuaq (Sondre Strømfjord) to the north and Terceira (Azores) to the south.
Also shown—as shaded areas—are range contours without shading for non-ETOPS (no more than 60 minutes engine-out flying time), light shading for ETOPS-90, darker shading for ETOPS-120, and the darkest shading for two areas beyond 120-minutes flying time on a single engine, including a small triangle northwest of the Azores and a much larger area southwest of the Azores (too far south to have been relevant to TWA 810.
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Karl L. Swartz.
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