Page:CAB Accident Report, TWA Flight 3 (January 1942).pdf/18

 fact that both the captain and the first officer, and particularly the latter (who apparently prepared the flight plan), had made a substantially larger percentage of flights via Boulder City than via Las Vegas, it seems likely that the average course out of Boulder City was inadvertently designated in the flight plan in place of the correct average course out of Las Vegas.

The evidence shows that in some instances flights proceed in approximately a straight line between the extremities of a given portion of the route without following the courses of the individual sectors. Apparently such practice is customary, under contact conditions, when the result is to keep the airplane on the right side of the airway. In any instance in which the direct course is used, it is apparent that the course flown will be approximately equivalent to the average course indicated on the flight plan (if the correct average course is entered).