This paper covers the performance of the Sperry SGN-10 Inertial Navigation System as demonstrated by the operation of dual systems installed in a standard operational configuration aboard four jet aircraft of Pan American World Airways incidental to a preoperational engineering evaluation programme conducted for the Federal Aviation Administration during the latter part of 1966. The primary object of this evaluation programme was to determine the system's capability of meeting the following requirements of the F.A.A.'s Advisory Circular covering the use of inertial navigation systems in U.S.- registered civil aircraft, namely:

(1) Maintain a position accuracy within 20 n.m. in the across-track dimension and 25 n.m. in the along-track dimension for 95 per cent of the time on flights up to and including ten hours duration.

(2) Automatically accomplish initial platform alignment in a normal manner in latitudes up to and including the highest normally used in civil aviation.

(3) Perform all its designed navigational functions in a normal manner at all latitudes, inclusive of polar and equatorial overflights.