Tigerair Australia and Airservices Australia have made changes to their procedures following an investigation into an incident where one of the carrier’s aircraft flew below the required altitude while coming in to land at Avalon on 30 June 2011.
The incident was one of three that contributed to the temporary grounding of Tigerair Australia, previously Tiger Airways Australia, by the Civil Aviation Safety Authority for six weeks in July and August 2011.
The Airbus A320, registered as VH-VNC, was operating a flight from Sydney to Avalon, the Australian Transport Safety Bureau (ATSB) said in its investigation report.
Following an unsuccessful attempt to land on runway 18, as tailwinds on the approach exceeded the limits for landing – as per Tigerair’s operating procedures – air traffic control directed the aircraft to climb to 3,000ft (914m) and reposition for a visual approach to land on runway 36.
During that repositioning, the aircraft descended below the assigned altitude without clearance. As it continued the approach, the aircraft descended to 1,600ft at a point where the minimum permitted altitude was 2,000ft. The aircraft subsequently landed on runway 36.
In its analysis of the incident, the ATSB found that Tigerair Australia's documentation and training package for Avalon airspace and its night visual approach guidance “contained incorrect material and omissions that increased the risk of confusion and misunderstanding by flight crews”.
Following the event, Tigerair has adopted new documentation and training for approaches to Avalon, and although it no longer operates scheduled services there, these have been incorporated into its initial flightcrew training.
Changes have also been made to Airservices Australia’s operations manual relating to the issuing of night visual approach clearances for instrument flight rules.
The ATSB also noted that the incident highlights how flightcrew need to be adequately prepared to avoid the effects of high workload during landing approaches.