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Fatigue and limited approach guidance factors in A330 descent below glide slope
10 July 2015
Descent profile of the A330 at Melbourne (ATSB)

Descent profile of the A330 at Melbourne (ATSB)

The Australian Transport Safety Bureau (ATSB) concluded that the captain’s fatigue and the limited guidance for visual approaches factors in an an incident in which an Airbus A330 descended below the normal descent profile.

The flight crew of a Qantas Airbus A330 aircraft, registered VH-EBV, was conducting a visual approach to Melbourne Airport, Australia. The captain was the pilot flying with autopilot engaged.

Soon after being cleared for the approach, on descent through 3,000 ft, the captain set an altitude target of 1,000 ft in the auto-flight system and selected the landing gear down, the first stage of wing flap and 180 kt as the target speed. The descent was continued in auto-flight open descent mode and reached a maximum of 2,200 ft/min. As the aircraft was descending through about 1,800 ft the first officer advised the captain that they were low. The captain reduced the rate of descent by selecting auto-flight vertical speed mode but a short time later the enhanced ground proximity warning system (EGPWS) provided ‘TERRAIN’ alerts followed by ‘PULL UP’ warnings. The crew carried out an EGPWS recovery manoeuvre and subsequently landed via an instrument approach.

At the time of the EGPWS alert the aircraft had descended to 1,400 ft, which in that area was 600 ft above ground level, with 9 NM (17 km) to run to touchdown. This was 100 ft below the control area lower limit and 1,900 ft below a normal 3° descent profile.

The ATSB found that during the visual approach the captain’s performance capability was probably reduced due to the combined effects of disrupted and restricted sleep, a limited recent food intake and a cold/virus. The captain assessed the aircraft’s flight path using glide slope indications that were not valid. This resulted in an incorrect assessment that the aircraft was above the nominal descent profile.

In addition, the combination of the selection of an ineffective altitude target while using the auto-flight open descent mode and ineffective monitoring of the aircraft’s flight path resulted in a significant deviation below the nominal descent profile. The flight crew’s action in reducing the aircraft’s rate of descent following their comprehension of the altitude deviation did not prevent the aircraft descending outside controlled airspace and the activation of the EGPWS.

The ATSB also identified that limited guidance was provided by Qantas on the conduct of a visual approach and the associated briefing required to ensure flight crew had a shared understanding of the intended approach.

In response to this occurrence Qantas updated their training material for visual approaches and enhanced similar material in their captain/first officer conversion/promotion training books. In addition, targeted questions were developed that required check pilot sign-off for proficiency. Finally, visual approaches were included as a discussion subject during flight crew route checks for the period 2013–2015.

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