... 1.o zoo Ä 9 Ё 20000 l! çà» g l зо ~ „A "' f “i” zo 100 ”я, 6 mono á X o L o o 'IBLO 50 60 70 80 90 20m 10 YEAR Fig. 6. Possible development of average speed, passengers per aircraft, and passengermiles per aircraft hour for the ICAO states.
International Council of the Aeronautical Sciences, 1964