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.
