A Batik Air 737-800 departs Canberra during the airline’s short-lived services between Bali and the capital. Photo: Canberra Airport.
A report by the Australian Transportation Safety Bureau (ATSB) has found that the short-lived airline service between Canberra and Bali almost came unstuck on its inaugural service, after the Batik Air airliner dropped below the minimum safe altitude while on approach to Canberra Airport.
On the evening of 13 June 2024, the 162-seat Boeing 737-800 departed Denpasar in Bali on the airline’s first service to Canberra. Favourable winds saw the aircraft arrive in the Canberra area nearly an hour ahead of schedule and before the Canberra control tower and approach air traffic control had opened for operations at 0600 on the morning of 14 June.
Rather than hold and wait for the tower to open, the crew elected to continue its arrival using common traffic advisory frequency (CTAF) procedure where aircraft remain separated around an airport using positional radio calls.
The crew overflew the AVBEG waypoint located between Yass and Gunning, and elected to operate the AVBEG 5A standard arrival route (STAR) which uses satellite-based positioning waypoints to transition aircraft from enroute flight to initial approach fix waypoints.
The AVBEG 5A STAR takes aircraft west of Canberra on a downwind leg parallel to Canberra’s runway, over the Tidbinbilla restricted area which has a minimum altitude of 10,000 feet, and then turns east on a perpendicular base leg before turning north to intercept Canberra’s main Runway 35 centreline for final approach.
Because of high terrain west and south of Tidbinbilla and south of the airport, there are a number of minimum safe altitudes approaching or holding aircraft cannot drop below.
While the crew elected to use AVBEG 5 for their approach, they had not been cleared by Air Services Australia controllers to do so.
“The crew did not request, nor were they provided clearance to use this route by Melbourne Centre,” ATSB Chief Commissioner Angus Mitchell said in the report which was released on 17 June.
“Air traffic control in Melbourne expected them to follow their cleared track direct to Canberra, which would have descended the aircraft out of controlled airspace as it approached Canberra.
“Instead, the crew deviated from the clearance and flew the AVBEG 5A STAR.”
The aircraft’s arrival in the Canberra area also coincided with a shift change at Melbourne Centre, with the oncoming controller reminding the crew to maintain an altitude of 10,000 feet overhead Tidbinbilla’s restricted airspace before clearing them to descend.
A map showing the MOMBI holding pattern flown by the Batik Air crew and its proximity to Mount Campbell. Image: ATSB.
“The STAR the flight crew was following takes aircraft over the Tidbinbilla restricted airspace at 10,000 ft by design,” Mr Mitchell said.
“This intervention by the controller resulted in the aircraft becoming higher than the desired descent profile, as well as the crew becoming confused regarding the airspace classification for the arrival and approach.”
Because the aircraft was too high to continue a standard AVBEG 5A approach, the aircraft captain elected to conduct a holding pattern – essentially a 360-degree descending turn – at the MOMBI approach waypoint which is located roughly between Googong south of Queanbeyan and Theodore in Tuggeranong.
“This holding pattern was not correctly flown,” Mr Mitchell said, adding that, “the aircraft was manoeuvred significantly below the minimum safe altitude, and terrain clearance reduced to a minimum of 924 ft above ground level in darkness.”
At the point the aircraft had descended to 924 feet or less than 300 metres, it was flying less than a kilometre east of the 1200 metre Mt Campbell which rises several hundred feet above the surrounding area. It should in fact have been at 5100 feet above sea level or at least 1900 feet above ground level.
The ATSB added that during the approach and while in uncontrolled airspace, the CTAF was not selected by the flight crew and appropriate radio broadcasts were not made.
The aircraft continued its flight and landed safely at Canberra.
The ATSB has attributed the incident to several factors, including the preparatory work done by the airline prior to the inaugural flight into an unfamiliar airport.
“Batik Air’s change management processes were not effective at fully identifying and mitigating the risks associated with the commencement of the Denpasar to Canberra route,” Mr Mitchell said.
“This included the airline not ensuring flight crew completed all CTAF training prior to operating flights into Australia, where use of these procedures could be required – as in this instance.”
In response, the airline has undertaken to improve internal communication to its crews on the importance of a comprehensive approach briefing, and to complete CTAF training for all flight crew operating on Australian services.
After commencing the new service with three flights per week, this was scaled back to two services per week after just six weeks of operations, before the service was suspended in October 2024 due to a lack of patronage.
