The history of EL AL "Star in the Sky" by Marvin Goldman ISBN 0-9626730-0-5 has the following on EL AL Britannia operations
"Before scheduled service with the Britannia started across the North Atlantic , EL AL set a primary goal of making almost all transatlantic flights without an intermediate stop at Gander, Goose bay or Elsewhere. J E D Williams ,EL AL s manager of Technical Planning & Development at the time initiated an extensive study to see how the Britannia could be operated most efficiently to eliminate these stops. All known variables were studied , including prevailing winds , payload and fuel burn. EL AL also invested in some 365 hours of crew training and route proving.
EL AL learned that if westbound flight time exceeded 12 hr 20 min , an intermediate refuelling stop at Goose Bay , Gander or Boston would be required. The airline also noted that, by departing from the Great Circle route in search of better wind conditions , an average of 55 minutes could be saved. Also , as fuel was burnt and the aircraft became lighter, optimum performance and fuel consumtion could be achieved by allowing the aircraft to drift upwards about 245m per hour with the aircraft initially cruising at about 6700m and slowly rising to 9150m. Procedures were also adopted to vary this general plan according to the winds experienced at these levels.
.....during the first eleven months of Britannia operations EL AL completed over 300 transatlantic flights and more than 90% were non stop. Whenever a stop was made it was due to unusual weather, traffic or load conditions."
EL AL marketing made good use of this performance, as per the following copy ad from the same source.
