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Recommendation issued to: AirServices Australia

Recommendation details
Output No: R19970150
Date issued: 01 October 1997
Safety action status:
Background:

SUBJECT

Comprehensive systems safety analysis of the simultaneous opposite direction parallel runway operations (SODPROPS).


OCCURRENCE SUMMARY

Occurrence 9700052

Simultaneous opposite direction parallel runway operations (SODPROPS) were introduced at Sydney (Kingsford-Smith) Airport, whereby arriving aircraft approach and land on one runway concurrently with aircraft departures from the parallel runway, in the opposite direction.

In this occurrence, an A320 aircraft was to depart from runway 16 Left and the A320 crew were assigned a radar departure with an initial left turn onto 115 degrees. The crew mistakenly dialled 155 degrees into their flight management system (FMS), despite correctly acknowledging the assigned heading of 115 degrees.

There was an aircraft approaching runway 34 Left, the reciprocal parallel runway, under the SODPROPS procedure.

After takeoff, when the A320 crew selected the heading mode on the FMS, they realised that they had set the incorrect heading. They continued on the runway heading until the correct heading could be confirmed. The Tower controller was not able to instruct the crew to turn left as they had already transferred to the Departures South (DEPS) frequency.

The Departures South controller instructed the A320 crew to turn left onto 115 degrees and the aircraft did not breach the separation standard for the approach in this instance.

The investigation found no record of any significant analysis of the risks associated with the development and adoption of SODPROPS for Australian use.

SAFETY DEFICIENCY

The safety implications of SODPROPS were not adequately addressed prior to the introduction of the procedure at Sydney Airport.


ANALYSIS

Investigation of the occurrence found that the Civil Aviation Safety Authority (CASA) adapted a USA Federal Aviation Administration (FAA) air traffic control spacing and sequencing standard (FAA 7110.65J) and incorporated it into the CASA Manual of Operational Standards part 3, para. 5.9 "Simultaneous Opposite Direction Operations". There was no record that CASA had conducted any significant analysis of the risks associated with the SODPROPS procedure

Airservices Australia held an industry seminar in September 1996 to discuss proposed Sydney traffic management procedures including the limited use of SODPROPS. At this seminar several participants questioned the extent of risk analysis that had been conducted to ensure that SODPROPS provided adequate levels of safety during all operations. The risk analysis provided to the industry indicated that a form of quantitative modelling had been conducted but that the analysis had been performed on a narrow set of data. The assumptions for the modelling were not analysed and the model itself was not validated as required in the Legislative Instrument Proposal (LIP) for the safety regulation of Airservices Australia. The analysis considered localiser track keeping and departure procedure compliance. The available evidence indicates that the analysis was not comprehensive.

The Bureau investigated a serious occurrence at Sydney in 1991 involving a near collision following the introduction of Simultaneous Runway Operations (SIMOPS). One of the safety recommendations resulting from that investigation was that the then Civil Aviation Authority "ensure that, prior to the implementation of any significant change in operational procedures or regulations, a comprehensive systems safety analysis is carried out." Similarly, section 6.3 of the LIP specifically details the manner in which Airservices Australia is required to manage changes to systems, equipment or procedures to ensure that unacceptable hazards are eliminated by the time that the change is completed. There was no evidence that these requirements were met.

CASA advised Airservices Australia that the standard governing the use of SODPROPS was available for use without impediments to its application, providing that the risks associated with the changes were analysed to ensure that unacceptable hazards were eliminated before the change was completed. Airservices Australia based some of the safety analysis of SODPROPS on the use of similar overseas procedures at international airports. Investigation by the Bureau of overseas operations found that this premise was not substantiated. Some minor examples of international parallel opposite direction operations were found but were not regarded as sufficiently similar to the Sydney operation to be used to support Airservices Australia's risk analysis.

Although the use of SODPROPS was restricted to a limited time during the day, there is now the possibility of extending the hours of operation at KSA. As the SODPROPS procedure was introduced with an inadequate analysis of the risks it is imperative that a comprehensive systems safety analysis be carried out as soon as practicable.

Output text

The Bureau of Air Safety Investigation recommends that Airservices Australia conduct a comprehensive systems safety analysis of simultaneous opposite direction parallel runway operations (SODPROPS).

The Bureau has made the following recommendation (R970151) to the Civil Aviation Safety Authority:

"The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority review the Operational Standard "Simultaneous Opposite Direction Operations" to ensure that it provides an acceptable level of safety."

Initial response
Date issued: 01 December 1997
Response from: AirServices Australia
Action status: Monitor
Response text:

I am writing in response to your occurrence report and the associated recommendation that Airservices "conduct a comprehensive systems safety analysis of simultaneous opposite direction parallel runway operations (SODPROPS)".

In addressing this recommendation, I commissioned a team to conduct an independent analysis of the SODPROPS procedure itself and the analysis that was conducted prior to the implementation of the procedure at Sydney Airport.

This team comprised representatives from ATS' Safety and Quality Management Branch, ATC specialists from Sydney and Brisbane. The team was assisted by expert support from CASA and the major domestic airlines.

In essence, the analysis team has produced a Safety Case (copy enclosed) addressing the safety issues identified by the original SODPROPS implementation team. This Safety Case has been augmented by a Fault Tree Analysis of the risk of failure of the SODPROPS procedure.

I must emphasise that the bulk of the analysis presented in the SODPROPS Safety Case reflects the extensive hazard analysis and risk mitigation work that was done by the implementation team prior to the implementation of SODPROPS.

Whilst it can be said that the data was not collated into a concise document (for which CASA and Airservices now advocate a Safety Case), the data was available in relevant files within the Sydney management system at the time of the BASI investigation.

The data used in this report was available in relevant files within the Sydney management system at the time of the BASI investigation.

The Fault Tree Analysis was compiled using probability data on human performance and on historical incident data.

The SODPROPS Safety Case provides the necessary assurance that SODPROPS is being operated at an acceptable level of safety.

ATSB response:

ATSB Note: The Bureau sent an email to Airservices Australia on the 15 July 1998 asking for further information in regard to actions taken by Airservices Australia.

Further correspondence
Date issued: 22 September 1998
Response from: AirServices Australia
Response status: Closed - Accepted
Response text:

I refer to your letter of 15 July in which you sought advice of any actions Airservices Australia has taken, or intends to take, to address the issues raised by Mr [name] in his report of his review of the SODPROPS safety case.

We note that [name supplied] conducted the review on behalf of the Bureau and that the Bureau has not made recommendations arising from this review, nor do you indicate that the Bureau supports [name] findings. Nevertheless, we are grateful for the opportunity to examine the report and address issues raised.

In relation to SODPROPS, [name] principle criticism related to the hazard identification process, the risk criteria and application of risk management principles. To address this criticism, Airservices conducted a workshop in Sydney to extend the level of hazard identification and relate the results to appropriate risk criteria. This workshop was chaired by [name supplied]. In addition, Airservices commissioned [name] to provide advice on risk optimisation measures that should be considered for Sydney SODPROPS. The results of this workshop and risk optimisation advice are being developed into a Phase 2 Safety Case for SODPROPS.

In keeping with our continuing commitment to enhance our management of the safety of air navigation, we intend incorporating into our safety management manual improvements noted from [name supplied], report and subsequent workshop.

 
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Last update 01 April 2011