This paper describes tests of an approach procedure in which aircraft approach the airport on a radial track, circle the airport on an orbit and finally approach to land on another radial track in line with the runway. Ninety-six approaches were made with a representative selection of airline pilots in an aircraft fitted with the Australian Distance Measuring and Multiple Track Range Equipment.

The flight tests provide information as to the accuracy with which pilots can follow a set track, both for track accuracy and turning, when provided with adequate navigation aids. The average time for the particular procedure used was 18 minutes, and 90% of all times were within ±1 minute of the average. Maximum departures from the correct track occurred during orbiting where the average track was 0·2 mile inside the nominal orbit, and in 90% of approaches the departure did not exceed ±0·8 mile. Detailed analysis of the turns is also given in which it is shown that, on the average, turns occupy ¾ minute instead of the ½ minute required for a correctly executed Rate 1 turn.