Aviation safety investigations & reports

Descent below minimum permitted altitude involving Boeing 747, N409MC, 11 km E of Melbourne Airport, VIC, 9 September 2012

Investigation number:
AO-2012-120
Status: Completed
Investigation completed

Final Report

Download Final report
[Download  PDF: 1.2MB]
 

What happened

On 9 September 2012, a Boeing 747 freight aircraft, operated by Atlas Air and registered N409MC, was approaching runway 34 at Melbourne Airport, Victoria, following a flight from Auckland, New Zealand.

The flight crew was conducting the LIZZI FIVE VICTOR standard arrival route (STAR) procedure that included a requirement not to descend below 2,500 ft until past the SHEED waypoint. They were issued clearance by air traffic control for a visual approach for runway 34 from the SHEED waypoint, conditional on not descending below 2,500 ft before SHEED. The flight crew read back the clearance without including the minimum altitude before passing SHEED and the controller did not query the incomplete read back. The flight crew initiated the visual approach and descended below the stipulated minimum of 2,500 ft prior to SHEED.

What the ATSB found

The ATSB found that the United States-based flight crew did not hear the requirement of the clearance to not descend until after passing the SHEED waypoint. Instead they read back what they believed to be a clearance for an immediate visual approach from their present position. This is a normal instruction during operations in United States airspace. The crew continued their approach to Melbourne Airport based on this understanding. There was no loss of separation with any aircraft.

The lack of detection by the controller of the crew’s incomplete read back represented a missed opportunity to alert the flight crew to not descend below 2,500 ft until after the SHEED waypoint.

Visual approaches from STARs are available elsewhere in Australia, but are not available for use by international operators of large jet aircraft. The approaches via SHEED to runway 34 at Melbourne are the only exception to this rule and are implemented with few additional defences to address the increased risk associated with this type of approach. In addition, the flight profile required from the SHEED waypoint to runway 34 is steeper than other approaches of this type in Australia, requiring a higher rate of descent. This increases the likelihood of an unstable approach.

What’s been done as a result

As a result of this occurrence, Airservices Australia (Airservices) is removing the provision in the Manual of Air Traffic Services for international Heavy and Super Heavy aircraft to use the SHEED visual segment. This permanent change to the Manual of Air Traffic Services is planned for November 2015, with a temporary local instruction to that effect to be issued by Airservices in the interim. In respect of the descent profile of the LIZZI FIVE RWY 34 VICTOR ARRIVAL, the Civil Aviation Safety Authority will engage with Airservices to ensure that the procedure meets all relevant instrument procedure design and ‘flyability’ standards.

Safety message

This occurrence highlights the importance of a shared understanding of a clearance between pilots and air traffic controllers, and the factors which may affect this understanding. It also underlines the importance of a thorough risk assessment in support of the design, modification and promulgation of approaches so that any increased risk is identified and addressed.

Download Final report
[Download  PDF: 1.2MB]
 
 
 

The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

Photo

To download, click the link, then right-click and select Save As.

Copyright in material obtained from other agencies, private individuals or organisations, belongs to those agencies, individuals or organisations and should be credited accordingly.

Safety Issues

Go to AO-2012-120-SI-01 - Go to AO-2012-120-SI-02 -

Assigning approaches to foreign operators

Unlike other Australian standard arrival routes that included a visual segment, the visual approach to runway 34 at Melbourne via the SHEED waypoint could be issued to super or heavy jet aircraft operated by foreign operators, despite there being more occurrences involving the SHEED waypoint than other comparable approaches.

Safety issue details
Issue number: AO-2012-120-SI-01
Who it affects: All foreign operators of super or heavy jet aircraft conducting a visual approach to runway 34 at Melbourne via the SHEED waypoint
Status: Adequately addressed

Design of the LIZZI FIVE RWY 34 VICTOR ARRIVAL at Melbourne Airport

The LIZZI FIVE RWY 34 VICTOR ARRIVAL required a 3.5° descent profile after passing the SHEED waypoint for visual approach to runway 34 at Melbourne, increasing the risk of an unstable approach.

Safety issue details
Issue number: AO-2012-120-SI-02
Who it affects: All flight crew of large jet aircraft conducting the visual approach via SHEED waypoint to runway 34 at Melbourne.
Status: Adequately addressed
General details
Date: 09 September 2012   Investigation status: Completed  
Time: 1748 EST   Investigation level: Complex - click for an explanation of investigation levels  
Location   (show map): 11 km E Melbourne Airport    
State: Victoria   Occurrence type: Operational non-compliance  
Release date: 01 September 2015   Occurrence class: Airspace  
Report status: Final   Occurrence category: Incident  
  Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 747  
Aircraft registration N409MC  
Serial number 30558/1242  
Type of operation Air Transport High Capacity  
Damage to aircraft Nil  
Departure point Auckland, NZ  
Destination Melbourne, VIC  
Last update 14 November 2018