Final report

Summary

 

What happened

On 15 August 2013, a Boeing 777 aircraft, registered VH-VPF and operated by Virgin Australia International Airlines, was conducting a visual approach to runway 34 at Melbourne Airport, Victoria. During the approach and after the waypoint SHEED, the aircraft descended below the approach path to about 500 ft above ground level. Upon recognising the descent profile error, the captain disengaged the autopilot and flew the aircraft level, re-intercepting the profile and continuing the approach to land.

What the ATSB found

The ATSB found that during the construction of the visual approach in the aircraft’s flight management system, the captain inadvertently entered an erroneous height against a waypoint, which was lower than required for that point. This resulted in the aircraft increasing the descent rate to meet this constraint, during which time it descended below profile. While the ATSB was not able to determine what led to the erroneous data entry or the error not being detected, a number of factors were identified that may have influenced the non-detection.

The ATSB also found that, due to extended wakefulness, the crew were probably experiencing fatigue at a level that has been demonstrated to affect performance, although fatigue could not be confirmed as contributing to the error in developing the approach profile. In addition, the ATSB noted that the guidance provided in the operator’s Route and Airport Information Manual increased the potential for the incorrect altitude to be entered into the aircraft’s flight management system for the waypoint.

What's been done as a result

The ATSB has been advised by Virgin Australia International Airlines that the SHEED approach is no longer available for use by its Boeing 777 crews.

Safety message

This occurrence highlights the factors that can influence the accuracy of data entry in critical systems and any associated checks. In addition, it reinforces the importance of monitoring descent profiles, irrespective of any expectation that the descent is being appropriately managed by the autoflight system, and taking appropriate action when a deviation from the desired profile is detected.

The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions