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What happened

On 18 June 2013, two Boeing 737 aircraft, VH-YIR operated by Virgin Australia Airlines Pty. Ltd. as Velocity 1384 and VH-VYK operated by Qantas Airways Ltd. as Qantas 735, were on scheduled flights to Adelaide, South Australia.

On nearing Adelaide, the forecast improvement in weather conditions had not occurred and as a result, both aircraft commenced a diversion to Mildura, Victoria. Upon arrival at Mildura, the actual weather conditions were significantly different to those forecast, in particular with visibility reduced in fog.

The flight crew of Qantas 735 conducted an instrument approach and landed below minima. The flight crew of Velocity 1384 also conducted an instrument approach and landed below minima in fog and with fuel below the fixed reserve.

What the ATSB found

The ATSB found that the weather deterioration at Adelaide did not appear on the forecast when both aircraft departed their respective ports and furthermore the forecast duration of the fog in the later, amended forecast showed a clearance time earlier than actually occurred. This meant that Qantas 735 continued to Adelaide with the expectation that the fog would clear prior to their arrival, which did not occur. It also influenced the decision making of the Virgin Australia flight watch personnel, who did not pass this weather to the flight crew of Velocity 1384.

In relation to the weather at Mildura, the ATSB found that the deterioration was significantly worse than originally forecast. This resulted in the need for both Qantas 735 and Velocity 1384 to land in conditions that were below minima. The ATSB identified that both flight crew uploaded sufficient fuel for the originally-forecast conditions in accordance with their operators’ fuel policy and the Civil Aviation Safety Authority requirements.

The ATSB also found that in certain weather patterns and at certain locations, fog is both rare and difficult to forecast reliably.

In addition, the ATSB noted that the industry expectation for the provision of flight information services was not aligned with that provided by Airservices Australia (Airservices). Further, it was identified that in certain circumstances, pilots will not be made aware of a deterioration of weather at an airport that has an Automatic Weather Information Service or other Automatic Broadcast Service. These services did not provide for the recognition and active dissemination of special weather reports (SPECI) to pilots, thereby not meeting the intent of the SPECI alerting function provided by controller-initiated flight information service.

What's been done as a result

In response to this occurrence, Airservices advised that they would work with the Bureau of Meteorology to explore feasible options to provide information on significant deteriorations in weather conditions to address the very high frequency radio range limitations of the automated broadcast services. In the meantime, Airservices has updated the Manual of Air Traffic Services to ensure dissemination of weather information from locations with an Automatic Weather Information Service should that service be unavailable.

The Bureau of Meteorology advised of various system changes and improvements in response to this occurrence. This included to equipment used in forecasting.

Virgin Australia Airlines Pty. Ltd. (Virgin) advised of a review and benchmarking exercise as part of its examination of this occurrence. This resulted in enhancements to Virgin’s flight planning and flight following policies, re-organisation of the flight following section and expansion of communication infrastructure across the Virgin fleet. In addition, Virgin’s pilot weather requirements have been clarified and enhanced.

In response to this occurrence the ATSB issued a safety recommendation to Airservices. This recommended that Airservices, as the issue owner, work in collaboration with the Bureau of Meteorology to instigate a system change to reinstate the alerting function of SPECI reports currently not available through an Automatic Broadcast Service.

Safety message

Pilots are reminded of their responsibility for collecting all relevant information to support inflight decision making. This includes weather and operational information for the destination, which should be considered prior to a decision point or point of no return.

It is important that pilots understand what will be provided under Airservices’ provision of flight information service and that they are also able to request weather and operational information from air traffic control. In addition, pilots should note the potential benefits of informing the controller of a non-normal situation. These include increased monitoring and support as required and the potential to reduce pilot workload in stressful situations.

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The occurrence

Context

Safety analysis

Findings

Safety issues and actions

Sources and submissions

Appendices

 
Download Interim Report
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Interim report released: 5 June 2014

What happened

On the morning of 18 June 2013, a Boeing Company 737 (B737) aircraft, registered VH-YIR and operated by Virgin Australia Airlines Pty Ltd was conducting a scheduled passenger service from Brisbane, Queensland to Adelaide, South Australia. On board were 6 crew members and 85 passengers.
 
On the same morning, another B737 aircraft, registered VH-VYK and operated by Qantas Airways Limited, was conducting a scheduled passenger service from Sydney, New South Wales, to Adelaide. On board were 6 crew and 146 passengers.
 
Due to unforecast weather in Adelaide, both aircraft diverted to an alternate airport at Mildura, Victoria. This airport was also affected by unforecast fog and low cloud at the time of their arrival.

Safety action

As a result of its developing understanding of the occurrence, the ATSB has commenced the following safety action:
 
Safety forum regarding the provision of operational information
The ATSB is planning to convene a safety forum in respect of the provision of operational information to the flight crews in this occurrence, and more generally. This forum is planned to include representatives from the Civil Aviation Safety Authority, Airservices Australia, the Bureau of Meteorology, the operators of VH-YIR and VH-VYK, and other relevant parties.
 
Reliability of aviation weather forecasts
As a result of this and other occurrences involving observed but not forecast weather, the ATSB has commenced research investigation AR-2013-200 Reliability of aviation weather forecasts. This investigation will analyse Bureau of Meteorology data across Australian airports, with a focus on those supporting regular public transport operations, and is subject to the availability of long-term data holdings of aviation forecasts and observations.

The investigation is continuing and will:

  • examine the accuracy of aviation meteorological products in Australia
  • examine the procedures used to provide information to flight crews from air traffic services and management of  changes to those procedures
  • examine the provision by the operators of information to the respective flight crews
  • examine the relevant recorded data
  • review the distribution, dissemination and sharing of operational information to the aviation industry as stipulated by the Civil Aviation Safety Authority, and enacted by Airservices Australia and the Bureau of Meteorology.

 


The information contained in this Interim report is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the ongoing investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this Interim report. As such, no analysis or findings are included in this report.

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Download Preliminary Report
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Preliminary report released 18 July 2013

On the morning of 18 June 2013, a Boeing 737 aircraft, registered VH-YIR and operated by Virgin Australia, was conducting a scheduled passenger service from Brisbane, Queensland to Adelaide, South Australia. On board were six crew members and 85 passengers.
 
On the same morning, another B737 aircraft, registered VH-VYK and operated by Qantas Airways, was conducting a scheduled passenger service from Sydney, New South Wales, to Adelaide. On board were six crew and 146 passengers.
 
Due to poor weather in Adelaide, both aircraft were forced to divert to an alternate airport (Mildura, Victoria). This airport was also affected by unforecast poor weather at the time of their arrival.
 
The ATSB’s ongoing investigation will examine the:

  • provision of information to flight crews from Air traffic services (ATS)
  • ATS policies and procedures affecting the flights
  • provision by the operators of information to the respective flight crews
  • the basis for the sequencing of the aircraft landings at Mildura
  • Bureau of Meteorology meteorological services and products as they applied to these flights
  • accuracy of aviation meteorological products in Australia.

_________

The information contained in this preliminary report is derived from the initial investigation of the occurrence. Readers are cautioned that there is the possibility that new evidence may become available that alters the circumstances as depicted in the report.

 


History

 

Updated: 2 July 2013

The ATSB is continuing its investigation into the circumstances surrounding the diversion of a B737 aircraft, registered VH-YIR (YIR) and operated by Virgin Australia, to Mildura, Victoria on 18 June 2013. The reduced visibility at Adelaide Airport, South Australia that led to the diversion also affected a number of other aircraft, including another B737. This aircraft, registered VH-VYK and operated by Qantas, was en route from Sydney, New South Wales to Adelaide before also diverting to Mildura.

As a result of its increased understanding of events, the ATSB has expanded the scope of its investigation to examine both of these diversions and their broader context. The investigation title has been amended to reflect this expanded investigation focus, which will include examination of the:

  • forecasting and distribution of weather information by the Bureau of Meteorology
  • provision of weather and operational information by Airservices Australia to all aircraft that were affected by the reduced visibility at Adelaide
  • provision of weather and operational information to those aircraft by the operators
  • influence on the flight crews’ decision making of that information flow.

A preliminary factual report into the circumstances of the occurrence is anticipated by 18 July 2013, and the final report is expected to be completed within 12 months.

 

_________

The information contained in this web update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this web update. As such, no analysis or findings are included in this update.

 

 

 

 

Updated: 19 June 2013

At about 1015 EST on 18 June 2013 air traffic control advised the ATSB of a fuel related occurrence involving a Boeing 737-8FE (B737), registered VH-YIR, at Mildura Airport, Victoria. The aircraft, operated by Virgin Australia, was en route from Brisbane, Queensland, to Adelaide, South Australia, with five crew and 86 passengers on board when the crew diverted the aircraft to Mildura.

The aircraft had departed Brisbane at about 0630 that morning and carried sufficient fuel for the flight to Adelaide. On the basis of the weather forecasts at the time the aircraft departed Brisbane, there was no requirement to provide for an alternate airport to Adelaide. As the aircraft approached Adelaide, fog reduced the visibility at the airport to below the minimum required for landing. The crew diverted to Mildura and the aircraft landed safely at Mildura Airport at about 1010 following two instrument approaches.

The fog at Adelaide was not forecast when the aircraft left Brisbane. A number of other aircraft, in addition to the B737, returned to their departure airports or diverted to alternate airports as a result of the reduced visibility at Adelaide Airport.

The ATSB commenced an investigation at about 1100 on 18 June 2013 and the cockpit voice recorder and flight data recorder were removed from the aircraft and forwarded to the ATSB’s facilities in Canberra for download. The investigation is continuing and will involve:

  • examination of the recorded information
  • interviews with the flight crew of this and other affected aircraft
  • examination of the operator’s procedures
  • review of the relevant radio and radar data
  • examination of the relevant weather observations and forecasts.
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Safety issues

AO-2013-100-SI-01 - AO-2013-100-SI-02 -  

Limited provision of flight information service for some non major airports

For many non‑major airports in Australia, flight crews of arriving aircraft can access current weather information using an Automatic Weather Information Service via very high frequency radio, which has range limitations. Where this service is available, air traffic services will generally not alert pilots to significant deteriorations in current weather conditions at such airports, increasing the risk of pilots not being aware of the changes at an appropriate time to support their decision making.

Safety issue details
Issue number:AO-2013-100-SI-01
Who it affects:All pilots operating into non-major airports accessing an Automatic Weather Information Service


 

Alerting function of special weather reports (SPECI) is not met by the automatic broadcast services

The automatic broadcast services did not have the capacity to recognise and actively disseminate special weather reports (SPECI) to pilots, thus not meeting the intent of the SPECI alerting function provided by controller-initiated flight information service.

Safety issue details
Issue number:AO-2013-100-SI-02
Who it affects:All pilots operating into non-major airports accessing an automatic broadcast service
Status:Not addressed

 
General details
Date: 18 Jun 2013 Investigation status: Completed 
Time: 10:15 EST Investigation type: Occurrence Investigation 
Location   (show map):Mildura Airport Occurrence type:Low fuel 
State: Victoria Occurrence class: Operational 
Release date: 31 May 2016 Occurrence category: Serious Incident 
Report status: Final Highest injury level: None 
 
Aircraft 1 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737 
Aircraft registration: VH-YIR 
Serial number: 39925 
Operator: Virgin Australia 
Type of operation: Air Transport High Capacity 
Sector: Jet 
Damage to aircraft: Nil 
Departure point:Brisbane, Qld
Destination:Adelaide, SA
Aircraft 2 details
Aircraft manufacturer: The Boeing Company 
Aircraft model: 737 
Aircraft registration: VH-VYK 
Serial number: 34183 
Operator: Qantas 
Type of operation: Air Transport High Capacity 
Sector: Jet 
Damage to aircraft: Nil 
Departure point:Sydney, NSW
Destination:Adelaide, SA
 
 
 
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Last update 31 May 2016