Simultaneous opposite-direction parallel runway operations (SODPROPS) were being used at Kingsford-Smith Airport (KSA) Sydney. An Airbus Industrie A320 aircraft was departing towards the south from runway 16L and an international Boeing 747 (B747) was tracking towards the north, established on final approach for runway 34L. The A320 aircraft was crewed by two pilots, with the manipulating pilot seated on the right side undergoing training to be a training pilot. Only one of the pilots had previously flown the SODPROPS procedure but during the departure briefing, the pilots discussed the requirement to turn left after takeoff.
The SODPROPS procedures were carried out by the aerodrome controllers in accordance with the Sydney District Office local instructions approved by Airservices Australia (Airservices), with the exception that the A320 crew was assigned a radar departure with an initial left turn onto 115 degrees instead of the preferred BOTANY BAY HEADS ONE Visual Departure procedure. The crew mistakenly dialled 155 degrees into the aircraft's flight control unit (FCU) on the glareshield as the aircraft lined up on the runway, but correctly acknowledged to air traffic control (ATC) the assigned heading of 115 degrees.
After takeoff, when the crew selected the heading mode on the FCU, they realised that they had set an incorrect heading and maintained runway heading (155 degrees). The aerodrome controller saw that the A320 did not turn left as instructed, but as the crew had already transferred to the departures south (Departures (S)) frequency, he was not able to instruct them to turn left onto the correct heading. When communications were established with Departures (S), that controller directed the crew to turn left to 115 degrees. The A320 crew reported that they had the arriving B747 in sight at all times, but the crew of the B747 did not sight the A320.
The aircraft did not breach the separation standard for the SODPROPS approach.
History of SODPROPS
The Civil Aviation Safety Authority (CASA) adapted a US Federal Aviation Administration (FAA) air traffic control spacing and sequencing standard (FAA 7110.65J) and incorporated it into the CASA Manual of Operational Standards in November 1994. The FAA standard was used by the Parallel Runway Standards Evaluation Group to develop a procedure for Australian use. This group comprised regulatory and air traffic services elements of the then Civil Aviation Authority along with other members of the aviation industry. The FAA standard was modified by adding a requirement that the departure runway course must diverge 15 degrees away from the approach course to the opposite direction runway.
The modified FAA standard was introduced into service at Sydney airport together with other changes identified as being able to meet government policies in relation to operations and noise abatement procedures at that airport. Airservices, which was responsible for Australian airspace management from 1 July 1995, planned to commence SODPROPS on 19 October 1996. Officers from Airservices organised an industry seminar for 26 September 1996 to discuss the proposed new traffic management procedures associated with SODPROPS and with the use of runway 34R for departures. 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.
On 10 October 1996, a senior officer from Airservices wrote to CASA, seeking confirmation that the standard governing the use of SODPROPS was available for use without impediments to its application. In response to this query, a senior CASA officer replied that there was no impediment to the use of the standard, but reminded Airservices that "the safety and change management standards for Airservices require you to analyse the risks associated with the changes to ensure that unacceptable hazards are eliminated before the change is completed".
During a meeting with CASA representatives on 15 October 1996, senior Airservices officers advised that "it [Airservices] had completed a formal change process, including safety analysis, hazard analysis, training, etc. and that all risks had had correction procedures put in place".
On 17 October 1996, an Airservices officer from Sydney wrote to a domestic operator and supplied details of risk analysis conducted for the implementation of SODPROPS. This letter advised that the following three risk categories had been examined:
- "approach track keeping and associated flight crew or ATC blunders";
- "departure procedure compliance, engine failure or other aircraft malfunction on take-off, or flight crew/ATC blunders"; and
- "Air Traffic Management risk".
Departures from runway 34R and SODPROPS both commenced on 19 October 1996.
SODPROPS risk analysis
Section 6.3 of the Legislative Instrument Proposal (LIP) for the Safety Regulation of Airservices Australia specifically detailed the manner in which Airservices was required by CASA to control and manage changes to systems, equipment or procedures to ensure that unacceptable hazards were eliminated by the time the change was completed. The BASI investigation found no evidence that the requirements of this section had been complied with. One form of risk analysis methodology mentioned in the LIP as being acceptable was "assessment of overseas experience..". Claims by Airservices that airspace managers at various overseas airports utilised procedures similar to SODPROPS, were not substantiated. Although the BASI team discovered several examples of international, opposite-direction, parallel runway operations, these were not regarded as sufficiently similar to the Sydney operation to be used as justification in the risk analysis.
The risk analysis provided to the domestic operator, with a matrix of data, suggested that a form of quantitative modelling had been conducted using a narrow set of data. The assumptions for the modelling were not analysed and the model itself was not validated as required in the LIP.
The BASI investigators were supplied with the same matrix of data when Airservices officers were asked to supply full details of the risk analysis associated with the introduction of SODPROPS.
Additionally, there was no record available to the investigation team to indicate that CASA or the Parallel Runway Standards Evaluation Group had conducted any significant analysis of the risks associated with the development and adoption of the SODPROPS standard for Australian use.
The crew of the A320 set an incorrect heading into the FCU as they were turning onto the runway. They had discussed the need to turn left after takeoff and had correctly read back to the aerodrome controller the radar heading for this turn after takeoff. Both pilots had followed the company procedures required for setting the departure heading into the FCU, but the cross-check process did not detect the incorrect heading that had been set. It is possible that the training situation in the cockpit, lack of familiarity with the procedure, and the action of setting the heading whilst turning onto the runway had prevented the pilots from recognising that the heading they had set in the FCU was, in fact, the runway heading.
The aerodrome controller was unable to resolve the situation because when he determined that the A320 had not turned left, the A320 crew had already transferred to the Departures (S) frequency. Had the A320 crew remained on the tower frequency until established on the assigned departure heading, the controller would have been able to immediately instruct the crew to turn onto the correct heading.
The SODPROPS procedure was introduced to the Sydney Airport environment with neither the regulator nor the airservice provider having adequately analysed the risks associated with the implementation of the standard. CASA did not critically examine how the standard was developed by the FAA and did not determine if any restrictions were applied when the standard was utilised in the USA. Furthermore, CASA did not determine the extent to which this standard was used in other countries where the regulators' experience might have been able to influence the standard's development for use in Australia.
Although Airservices had agreed to comply with the requirements of the LIP until the document was signed into law by the Minister, the evidence indicated that the requirements for risk analysis of new procedures in the LIP were not complied with prior to the introduction of SODPROPS.
Airservices commenced the consultation process with industry less than 4 weeks prior to the planned implementation of the procedure. This period did not give the industry sufficient time to consider the procedure, or to develop and distribute internal procedures that incorporated the new operation. Because industry representatives were provided with details of the risk analysis 2 days before the operation was due to start, there was insufficient time for industry analysis of those details.
- The crew of the A320 dialled an incorrect heading into the FCU, although the pilot in command read the correct heading back to ATC.
- The A320 crew followed normal procedure and contacted Departures (S) as soon as practicable after takeoff. This frequency change prevented the aerodrome controller correcting the tracking error of the A320 crew.
- The Civil Aviation Safety Authority adopted the SODPROPS standard without critical analysis of the FAA standard or the risks associated with the application of the standard to Australian operations.
- Airservices Australia implemented the standard without fully complying with the requirements of section 6.3 of the LIP.
As a result of the investigation into this occurrence, the Bureau of Air Safety Investigation issued the following recommendations:
"The Bureau of Air Safety Investigation recommends that Airservices Australia review the requirements detailed in AIP Supplement H73/96, (10 October 1996) Simultaneous Opposite Direction Parallel Runway Operations Sydney (KSA) and:
- develop a SID which incorporates a standard left hand turn after takeoff, and tracks the departing aircraft through the heads of Botany Bay in accordance with accepted separation and noise-abatement procedures,
- have the departing aircraft remain on tower frequency until the assigned turn has been completed, and
- develop a pilot aid for inclusion in departure and approach procedures (DAP) East. This chart should depict the expected flight path of aircraft departing and arriving under SODPROPS, and could be similar to the pilot-aid (Issue 1, 14 September 1995), located in DAP East, advising pilots about independent visual approaches at Sydney Airport."
Response from Airservices Australia received 4 March 1997:
"BASI has made three recommendations arising from Occurrence 9700052
Airservices has recently conducted a post implementation review (PIR) into SODPROPS at Sydney. Specific action undertaken by Airservices to address the BASI recommendations is as follows:
- An appropriate SID will be developed which will be standard for all departures from Rwy 16L (not specific to SODPROPS). Until then the RADAR 6 departure with specific headings will continue to be used.
The BOTANY BAY HEADS Visual departure is no longer considered practical for jet aircraft owing to the difficulty in navigating to the Heads with high body angles and the possibility of entering cloud above 3000 feet prior to reaching the Heads.
- An instruction has been issued requiring ADCs to instruct departing aircraft under SODPROPS to remain on Tower frequency until established in the appropriate left turn.
- The recommendation to produce a pilot aid for inclusion into DAP (East) has been referred to CASA Flying Operations Branch for consideration/action.
While supporting these recommendations, Airservices is concerned that the report does not address the principle causal factor of the occurrence, namely flight crew error.
No reference is made to the following factors:
The assigned heading was correctly read back by the pilot but not entered into the FMS;
The pilot called departures radar at the appropriate time but failed to read back the assigned heading;
The use of FMS below the LSALT."
Response classification: Closed-Accepted
Response received from the Civil Aviation Safety Authority 22 April 1997:
"I refer to BASI Interim Recommendation IR 970014 addressed to Airservices Australia concerning Simultaneous Opposite Direction Parallel Runway Operations (SODPROPS) at KSA Sydney. The following comments are provided from a CASA perspective.
The first point of the recommendation is that "a SID be developed which incorporates a standard left hand turn after take-off and tracks through the heads of Botany Bay in accordance with accepted separation and noise abatement procedures". The SODPROPS standard is a visual standard and obviously the last line in separation would be the visual element. The ATC procedures specified in the local instruction indicated that a Botany Bay visual departure should be issued to departing aircraft. CASA believes there is no point in developing a Standard Instrument Departure (SID) for a visual procedure, in fact it could stop pilots from looking outside.
The second point is that the departing aircraft should remain on the tower frequency until the departure turn has been completed. Airservices Australia have since implemented this.
Finally, it is recommended that a pilot aid on SODPROPS be developed. This is probably worthy of consideration but CASA believes that AIP SUP H73/96 may require amending to specifically indicate a section on departing aircraft. Other than a reference in the standard section to course divergence there is no specific indication regarding aircraft departure requirements."
Response classification: Closed-Accepted
"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 also 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."
Response received from Airservices Australia 1 December 1997:
"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, [and] 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."
Response classification: Open
R970151"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."
The Bureau also made the following recommendation (R970150) to Airservices Australia:"The Bureau of Air Safety Investigation recommends that Airservices Australia conduct a comprehensive systems safety analysis of simultaneous opposite direction parallel runway operations (SODPROPS)."
Response received from the Civil Aviation Safety Authority 27 November 1997:"I refer to your letter dated 1 October 1997 reference BS/970061 regarding Recommendation R970151.
CASA has reviewed the Operational Standard "Simultaneous Opposite Direction Operations" as you have recommended. Following Occurrence 9700052 on 5 January 1997 the instructions in AIP OPS paragraph 19.4 were changed by NOTAM to require pilots to remain on Tower frequency until instructed to change, thus enabling Tower to correct the kind of confusion evident during the occurrence. The amendment will be correctly inserted into the AIP OPS text by AIP Amendment List 20, effective 4 December 1997.
Given the change to procedures our conclusion is that the standard expressed in the CASA Manual of Operational Standards (MOS) Part 3 Chapter 5.9 is adequate.
The MOS standard will be further reviewed in the light of any study which may be undertaken by Airservices in response to your recommendation R970150."
Response classification: Open
Following the provision of the SODPROPS safety case the Bureau elected to have the document reviewed by an independent consultant with international experience in aviation risk management practices and procedures. The intent of the review was to ascertain whether the safety case undertaken by Airservices was a comprehensive safety case and whether it had adequately demonstrated that SODPROPS could be conducted at a reasonable level of safety.
The review of the safety case was conducted in the last week of March 1998. On receipt of the consultant's report it will be reviewed and any further action by the Bureau will be subject to the findings of the report.
|Date:||05 January 1997||Investigation status:||Completed|
|Time:||0630 hours ESuT|
|Location:||6 km SSE Sydney Airport|
|State:||New South Wales|
|Release date:||23 July 1999||Occurrence category:||Incident|
|Report status:||Final||Highest injury level:||None|
|Aircraft manufacturer||Airbus Industrie|
|Type of operation||Air Transport High Capacity|
|Damage to aircraft||Nil|
|Departure point||Sydney, NSW|
|Departure time||0630 hours ESuT|
|Role||Class of licence||Hours on type||Hours total|