As a replacement for the Loran A systems installed on approximately fifty B-707/300 aircraft and to have this replacement fully operational by the end of 1977 only two options were available: the very well proven but relatively costly inertial systems and the almost totally unproven but potentially much less costly Omega. Economic considerations played a major role in this choice in view of the limited remaining useful life of the aircraft involved. The general object of the programme was to assess the acceptability of Omega as a pilot-operated substitute for Loran A in aircraft also equipped with dual doppler/computer navigation systems. Critical aspects of the use of Omega which were to be investigated were:

(i) the availability of adequate Omega signal coverage on a reasonably worldwide basis,

(ii) the normal in-lane accuracy of the Omega position output,

(iii) the in-lane stability of the Omega position output, i.e. susceptibility to ‘lane-slip’,

(iv) the reliability of the airborne Omega hardware,

(v) the operational suitability of the control/display units.