This paper discusses navigation system accuracies achieved on North Atlantic routes by Air Canada, and the effect of doppler on the accuracy of navigation. Data are presented on track maintenance performance with doppler inoperative and operative, on performance over a prolonged recent period combining all results, whether doppler operative or inoperative, and on the frequency of gross errors.

Doppler was installed by Air Canada with the primary aim of reducing the gross track maintenance errors which seemed otherwise inevitable at jet speeds and altitudes. A comparison of the results given below indicates the deterioration which resulted when the DC-8 was introduced and no doppler was available, and show the improvement achieved after some experience with doppler.