The company’s Required Navigation Performance approach procedure allowed the flight crew to set the approach minimum altitude in the auto-flight system prior to commencing the approach. This did not ensure the altitude alerting system reflected the assigned altitude limit of 7,000 ft and removed the defence of that alert when the flight crew did not identify the disengagement of the flight management computer-derived VNAV PTH mode.
The procedure has been modified to ensure the last-assigned altitude remains in the auto-flight system as a defence against a descent below this level.
Qantas Airways Limited advised that the procedure that permitted the flight crew to set the approach minimum altitude on the Mode Control Panel (MCP) when cleared for the RNP-AR approach has been replaced. The new procedure requires that the flight crew retain the current altitude limit on the MCP until cleared for the approach and within approximately 2 NM (4 km) of the approach commencement, with the selection of the flight management computer-derived VNAV PTH indicated on the flight mode annunciator.
