An incident in which a PC‑12 aeromedical aircraft struck a temporary light being used to mark a closed section of taxiway at Adelaide Airport highlights the importance of effective communication and the potential for expectation bias.
The Royal Flying Doctor Service Pilatus PC‑12 was incorrectly cleared to enter a closed section of taxiway while taxiing for a night‑time take‑off on 4 November 2024, an ATSB investigation report details.
Although the closure was detailed in a NOTAM and the ATIS (automatic terminal information service) current for Adelaide Airport at the time, the aircraft subsequently entered the taxiway and struck one of three red lights being used to denote that the section of taxiway was closed.
"The pilot knew about the taxiway closure but, when they were given clearance to enter it, assumed the works had ended early," ATSB Director Transport Safety Stuart Macleod said.
Shortly after, the controller advised the pilot they had entered the closed taxiway and requested they stop and turn back.
An aerodrome works safety officer, in a nearby safety car, coordinated with the controller to remove the red lights from the taxiway to allow the aircraft to taxi back off the closed section. On entering the taxiway they advised they were removing debris from the taxiway.
The controller then asked the pilot if they wished to continue. After conferring with the aircraft flight nurse, the pilot assessed that the aircraft had not struck a light and advised the controller they would continue with departure.
"While the flight was uneventful, the possibility of damage meant an inspection should have been completed prior to continuing the flight," Mr Macleod noted.
The investigation report also noted that it was Adelaide Airport's general practice to use three red lights and no markers at night to denote a closed taxiway.
"The lighting used to identify the taxiway section as being closed was insufficient to draw the pilot's attention at night, and the required cone markers were not in place," Mr Macleod said.
"The use of only three red lights, in situations where there is increased background lighting such as the incident taxiway, reduced the prominence of unserviceable movement areas."
Adelaide Airport's method of working plan, required by CASA to ensure aerodrome works do not create a hazard to aircraft or cause confusion to pilots, did not specify a minimum number of unserviceability markers or lights to be used, the investigation found.
Moreover, CASA's aerodrome requirements and standards (under the Part 139 Manual of Standards) did not specify that both markers and unserviceability lights were required for a closed taxiway, and did not provide adequate recommendations for lighting at aerodromes with significant background lighting.
CASA has since advised it is updating its guidance on the use of both unserviceability cones and lights to designate closed taxiways at night.
"This incident highlights the importance of effective communication, and the potential for expectation bias," Mr Macleod concluded.
"For pilots, if you receive a clearance that contradicts a NOTAM or current ATIS information, you should question the clearance before continuing.
"For aerodrome operators, this incident reinforces that when assessing the adequacy of unserviceability lighting, consider the effects of any obscuring background lighting and increase the span of lighting if required."
You can find here the final report: Entry to a closed taxiway involving Pilatus PC-12/47E, VH-FXJ, Adelaide Airport, South Australia on 4 November 2024
