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Departure procedures misunderstanding contributed to serious loss of separation incident at Sydney Airport
28 July 2020

Likely flight crew confusion with Sydney-centric departure procedures contributed to a Boeing 777 turning right instead of left on departure from Sydney Airport, resulting in a serious airprox incident with an ATR 72 which had taken off from the parallel runway, an ATSB investigation notes.

The United Airlines Boeing 777-300ER had departed from Sydney Airport’s runway 34L bound for San Francisco and was cleared to follow a standard instrument departure (SID) requiring the aircraft to maintain runway heading until reaching 1,500 feet, at which point the aircraft was required to turn left and track towards Richmond, northwest of Sydney. However, the 777 instead climbed straight ahead through 1,500 feet to about 2,100 feet and then turned to the right, resulting in a loss of separation with the Virgin Australia ATR aircraft, which had departed from the parallel runway (runway 34R).

The ATSB’s investigation found that in entering the cleared ‘RIC5’ standard instrument departure in the 777’s flight management computer (FMC), the aircraft captain, who was the pilot flying, closed (removed) a deliberate ‘discontinuity’ – or gap – in the waypoint sequence. This discontinuity was pre-programmed to represent where air traffic control was to provide radar vectors to transition from the SID to join the planned oceanic track to San Francisco.

In removing the discontinuity, likely due to the captain’s limited exposure to the assignment of varying Sydney-centric departure procedures, the aircraft was in effect programmed to track direct to a navigation waypoint (DIPSO), about 45 nautical miles to the east of Sydney, after reaching the initial waypoint at 1,500 feet. This resulted in the right turn and the subsequent loss of separation with the ATR 72.

Removing the discontinuity would have been appropriate for many procedural transitions, which are commonplace in the United States, the ATSB noted. The ATSB’s investigation also notes that the pilot flying probably did not effectively communicate the changes made to the FMC coding to the other members of the flight crew, after reprogramming the FMC from the anticipated simpler ‘SYD1’ standard instrument departure, which had been entered based on previous experience.

More information: ATSB report

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