Jump to Content



A Beech 200 (Beech) was on an instrument flight rules (IFR) category flight from Wilcannia to Adelaide. The flight was to be initially conducted in non-controlled airspace up to flight level (FL) 165, then across a Class E controlled airspace (CTA) corridor (above FL165 between Dubbo and Broken Hill), prior to entering Class C CTA above FL200. The pilot was required to request a clearance from a Melbourne sector controller before entering CTA.

The aircraft departed Wilcannia and climbed to FL190 prior to the pilot requesting a clearance from Melbourne Centre. The sector controller estimated that the aircraft had entered the Class E corridor without a clearance. There were two formations of military aircraft in the area at FL170 and FL180 respectively that could have conflicted with the Beech. A subsequent check established that there had not been an infringement of separation standards.

The Class E corridor had been implemented on 3 December 1998 and was depicted on the Aeronautical Information Publication (AIP) chart L5 (3 December 1998). The width of the corridor was promulgated as 5 NM either side of the Dubbo-Broken Hill air route, and was depicted on the chart to scale. However, the width of the Class E corridor was increased to 25 NM either side of the route by a Notice to Airmen (NOTAM) on 8 March 1999. The chart was not due for amendment until 17 June 1999. Consequently, pilots who used the chart for operations in proximity to the corridor needed to be familiar with the NOTAM, and to draw the increased corridor width on the chart for reference, and/or remember to include the increased width in any navigation calculations.

The pilot of the Beech was undergoing a check on the day of the occurrence and had the appropriate charts, NOTAMs and weather information for the flight. The pilot was aware of the amended width of the Class E corridor and had regularly flown the route taken. A number of flights had been planned for the day but were subsequently cancelled. The pilot was therefore required to submit a new plan for the flight that was subsequently undertaken. Although the pilot submitted the new flight plan by facsimile, this was not received by the Melbourne briefing office. When the pilot departed Wilcannia he was advised by air traffic service staff that there were no details held for the flight. Consequently, the pilot was required to re-submit the plan. It was during this period of the flight that the pilot believed he may not have taken into account the amended width of the Class E corridor when estimating the time and point at which the aircraft would enter CTA. He was using a chart and graduated rule and suspected that he may have used the distance between Wilcannia and the corridor as depicted on the chart (approximately 46 NM) for his calculations instead of that actually available due to the amended corridor width (approximately 15 NM).

The combined demands of cockpit workload associated with the particular phase of flight, some self-imposed stress due to being under check, and having to re-submit the flight plan while airborne, probably resulted in the pilot being near to task saturation. Consequently, despite his previous awareness of the need to consider the amended width of the corridor, he forgot to take that into account in his calculations.

Share this page Comment