The Civil Aviation Safety Regulations Part 139 (Aerodromes) Manual of Standards 2019 section relating to the temporary closure of a taxiway at night did not:
Response by Civil Aviation Safety Authority (CASA)
CASA is currently developing Advisory Circular (AC) 139.C-15 v1.0 - Safe planning and conduct for aerodrome works and has undertaken to include guidance on the use of both unserviceability cones and lights to designate closed taxiways at night. That guidance will include consideration of the detrimental effect background lighting can have on identifying closed infrastructure. CASA also advised the review will include consideration of the use of reflective markings on cones used at night.
ATSB comment
CASA’s safety action provides a method to address the issue and the ATSB will continue to monitor the safety issue until the actions are completed. However, as the CASR Part 139 Manual of Standards details airport lighting requirements, the ATSB considers that similar changes to the MOS content would also be beneficial.
Advisory Circular (AC) AC139.C-15 v1.0 - Safe planning and conduct of aerodrome works is now published on the CASA website and addresses the concerns of the safety issue. The AC advises how many lights are required depending on the taxiway width and states that both markers and lights are required at night. It also advises aerodrome operators to consider the conspicuity of the lights against the background lighting.
The public consultation for Advisory Circular (AC) 139.C-15 v1.0 - Safe planning and conduct for aerodrome works was completed on 19 October 2025, with submissions currently being considered. CASA expects to have finalised the AC before close of Quarter 4 2025.
The ATSB will continue to monitor the safety issue and will review Advisory Circular (AC) 139.C-15 on completion.
CASA stated, the Advisory Circular is expected to be finalised 1st Quarter 2026.
The ATSB will continue to monitor the progress of the Advisory Circular.
AC 139.C-15 v1.0 - Safe planning and conduct of aerodrome works is now published on the CASA external website.
The AC provides the following information:
6 Aerodrome markings, markers and lighting
6.11 Unserviceability lights
6.11.2 The actual number of lights to be used depend on the width of the entrance to be closed.
Table 10: Number of unserviceability markers required for temporary taxiway closure provides information on the minimum number of unserviceability lights that could be used, unless otherwise determined through a risk assessment that more, or less lights are required. The
entrance to a taxiway or apron is the space between the edge lines. Where the paved surface is wider due to sealed shoulders, additional lights may need further consideration.
6.11.3 The intensity of the lights must be sufficient to ensure conspicuity considering the intensity of the adjacent lights and the general level of illumination i.e. background lighting.
Table 10: Number of unserviceability markers required for temporary taxiway closures
Taxiway width - Number of markers/lights - Location
7.5m - 3 (note 1 applies) - One unit on centreline, and one unit each side of centreline and spaced 3 m apart.
10.5m - 3 (note 1 applies) - One unit on centreline, and one unit each side of centreline and spaced 3 m apart.
15m - 5 (note 1 applies) - One unit on centreline, and two units each side of centreline and spaced 3 m apart.
23m - 7 (note 1 applies) - One unit on centreline, and two units each side of centreline and spaced 3 m apart.
Note 1: Where the width of the taxiway exceeds the minimum width, such as intersections with other taxiways, additional markers, and lights for night closures, should be considered.
Note 2: The Part 139 Manual of Standards does not differentiate between the use of markers during daylight hours or night therefore markers should be used at night as well as unserviceability lights.
Additional consideration may be given to using reflective bands or stripes which are visible at night if determined necessary through a risk assessment.
The AC adequately addresses the concerns raised in the Safety Issue.
