Near collision involving a Cessna 404, VH-ANM and a Cessna 172, VH-MJK, at Bathurst Island Airport, Northern Territory, on 15 August 2015

What happened

On 15 August 2015, the student pilot of a Cessna 172 aircraft, registered VH-MJK (MJK) conducted a solo flight from Emkaytee aeroplane landing area (ALA) to Bathurst Island Airport, Northern Territory (Figure 1). There the student pilot completed touch-and-go circuits for about 30 minutes on runway 15.

Figure 1: Image showing Bathurst Island, Darwin and Emkaytee airports

Source: Google earth – annotated by the ATSB

At about 1210 Central Standard Time (CST), a Cessna 404 aircraft, registered VH-ANM (ANM) and operated by Hardy Aviation, departed from Darwin Airport, Northern Territory, on a scheduled flight to Bathurst Island, with a pilot and five passengers on board. The pilot broadcast when inbound and about 15 NM from Bathurst Island Airport on the common traffic advisory frequency (CTAF) of 126.5 MHz, and did not receive any response. At about 1220, the aircraft joined on the downwind leg of the circuit for runway 15 at 1,000 ft above ground level and broadcast joining the circuit. As the aircraft turned onto base, the pilot sighted MJK also on base, at the same height, closer to the runway and estimated it was about 150 m away (Figure 2).

The pilot of ANM immediately manoeuvred the aircraft to the west to increase separation between the two aircraft. After unsuccessfully trying to contact the pilot of MJK on the CTAF, the pilot of ANM briefly selected frequency 126.7 MHz to try to communicate with the pilot of MJK, but again did not receive a response. The pilot of ANM observed MJK conduct a touch-and-go, and kept that aircraft in sight, while overflying and re-joining the circuit on the crosswind leg.

After the touch-and-go, when upwind of the runway at about 500 ft above ground level, the pilot of MJK sighted ANM. ANM was then to the left, above MJK at 1,000 ft, and turning onto the downwind leg. The pilot of MJK then saw that the radio was selected to frequency 126.6 MHz. The pilot checked their flight plan, noted that the correct frequency was 126.5, and immediately changed the radio to that frequency. The pilot of MJK then broadcast a departure call on the CTAF. The pilot of ANM then contacted the pilot of MJK, who advised that the radio had been on the wrong frequency.

Figure 2: Bathurst Island Airport showing approximate aircraft tracks and relative positions

Source: Google earth – annotated by the ATSB

The pilot of ANM continued the approach, and landed at Bathurst Island, and MJK returned to Emkaytee without further incident.

The radar data provided to the ATSB by Darwin air traffic control, indicated the aircraft came within about 100 ft vertically and 0.6 NM at the closest proximity (Figure 3).

Figure 3: Radar display showing relative aircraft positions

Source: Department of Defence – annotated by the ATSB

Safety action

Whether or not the ATSB identifies safety issues in the course of an investigation, relevant organisations may proactively initiate safety action in order to reduce their safety risk. The ATSB has been advised of the following proactive safety action in response to this occurrence.

Operator of VH-ANM

As a result of this occurrence, the operator of VH-ANM advised the ATSB that they have taken following safety action:

Notice to company pilots

The Chief Pilot distributed a notice to all company pilots advising them of the incident. The notice stated that the Tiwi Islands continue to be a hot spot for traffic, and reminded pilots to be ‘doubly aware’ when operating in the area.

Safety message

The pilot of MJK commented that there were three important learnings from this incident:

• crosscheck the selected frequency against the flight planning notes
• ensure the selector reaches the detent when selecting a radio frequency
• listen for the ‘beep-back’ response from the CTAF to verify the correct frequency has been selected.

An aerodrome frequency response unit (AFRU) identifies correct radio frequency selection at non-towered aerodromes. The AFRU automatically responds to a transmission on the CTAF either with a pre-recorded voice message, if no transmission has been received in the previous five minutes, or with a beep-back.

The booklet A pilot’s guide to staying safe in the vicinity of non-controlled aerodromes outlines many of the common problems that occur at non-towered aerodromes, and offers useful strategies to keep yourself and other pilots safe.

Aviation Short Investigations Bulletin Issue 44