| Occurrence Briefs are concise reports that detail the facts surrounding a transport safety occurrence, as received in the initial notification and any follow-up enquiries. They provide an opportunity to share safety messages in the absence of an investigation. |
What happened
On 19 February 2018, just before 0910 Eastern Daylight-saving Time (EDT), the crew of a Boeing 737-800 was preparing for departure from Sydney Airport, New South Wales (NSW) to Gold Coast Airport, Queensland (Qld). There were six crew and 168 passengers on board. The planned flight time was 1 hour 20 minutes. To prepare for the short sector the crew programmed their anticipated approach for Gold Coast Airport into the aircraft’s Flight Management System (FMS).[1] The approach was a series of waypoints described by the GREAV SIX Standard Arrival Route (STAR).[2]
Prior to descent into the airport, the crew received and read back a different approach – the ROONY FOUR STAR – and were cleared to descend to flight level (FL) 250.[3] As the aircraft passed ROONY it commenced a turn 11º to the left, deviating from the agreed route. Route 2 in the FMS carrying the GREAV SIX STAR was still active in the aircraft’s FMS. The crew did not detect the anomaly.
Air Traffic Control (ATC) identified the deviation and asked the crew which STAR they would like to follow. The crew, recognising the GREAV SIX STAR was already programmed and checked, requested that approach from ATC. The aircraft was re-cleared on the GREAV SIX STAR and a normal approach and landing was conducted.
Safety message
This incident highlights the importance of ongoing verification, by flight crews, of the data the aircraft is working with at various stages of flight. The route data that was entered into the FMS was correctly keyed and had an intended purpose at the time of entry; however, it was no longer suitable for use in the later stages of the flight, when a different clearance requiring different waypoint data was provided.
ATC was able to alert the crew to the flight path deviation. ATC was also able to support the crew at a critical time by providing the opportunity to continue the approach utilising the data that was programmed and active in the FMS. This changed the circumstance of the operation to render the data valid again.
The ATSB SafetyWatch highlights the broad safety concerns that come out of our investigation findings and from the occurrence data reported to us by industry. One of the safety concerns relates to data input errors.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.
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- Flight Management System (FMS): a navigation, operations and performance computer used by the crew to manage the aircraft and flight. (Skybrary)
- Standard Arrival Route (STAR): a published approach procedure used to deconflict traffic, and provide predictable movement of traffic to simplify management of airport arrivals. (Airservices Australia)
- Flight level: at altitudes above 10,000 ft in Australia, an aircraft’s height above mean sea level is referred to as a flight level (FL). FL 250 equates to 25,000 ft. (Airservices Australia)