Civil Aviation Safety Regulations Part 139 Manual of Standards requirements

The Civil Aviation Safety Regulations Part 139 Manual of Standards did not recommend or provide standardised options for movement area guidance signs or other visual aids to draw flight crew attention to the start of take-off position, especially those distant from a displaced threshold and not coincident with a taxiway/runway intersection.

The ATSB acknowledges CASA's proposal to consider future amendments to the Part 139 MOS resulting from Annex 14 Volume I Amendment 18, which includes unserviceability signage. The ATSB also appreciates CASA's consideration of visual aids to mark a temporary start of take-off (SOT) position in Advisory Circular (AC) 139.C-15 - Safe planning and conduct of aerodrome works. The safety issue remains open with safety action pending, in anticipation of inclusion of visual aids for the SOT in the AC to be published in Q4 of 2025 and inclusion of unserviceability signage in the Part 139 MOS consistent with Annex 14 Amendment 18.

Response by the Civil Aviation Safety Authority

On 31 October 2025, the Civil Aviation Safety Authority (CASA) provided the following response to the safety issue.

CASA has announced proposed amendments to Part 139 [Manual of Standards] MOS, to incorporate Amendment 15 to Annex 14 Volume1. CASA expects to publish the updated Part 139 MOS in Quarter 4 of 2025.

Amendment 18 to Annex 14 Volume I is in the early stages of consideration and any future amendments to the Part 139 MOS resulting from Amendment 18 will be progressed in accordance with CASA’s normal regulatory process, including public consultation.

It is not intended to delay actions to adopt Amendment 15 in order to include changes to the Part 139 MOS to adopt Amendment 18. This should be reflected accordingly.

Visual aids to mark a temporary start of take-off run available (SOT), where SOT is not co-located with the permanent runway end, or a temporary displaced threshold, is currently being considered by CASA as part of the development of Advisory Circular 139.C-15 safe planning and conduct of aerodrome works. A report will be developed for the National Runway Safety Group to consider. A report will be submitted to the November 2025 NRSG meeting.

To further improve the development of [method of working plan] MOWP, in AC 139.C-15 CASA has included a sample list of stakeholders for airports to consider, and a range of purposes for an MOWP to assist the development of the document. CASA intends to publish AC 139.C-15 in Q4 of 2025.

ATSB comment

The ATSB acknowledges CASA's proposal to consider future amendments to the Part 139 MOS resulting from Annex 14 Volume I Amendment 18, which includes unserviceability signage. The ATSB also appreciates CASA's consideration of visual aids to mark a temporary start of take-off (SOT) position in Advisory Circular (AC) 139.C-15 - Safe planning and conduct of aerodrome works. The safety issue remains open with safety action pending, in anticipation of inclusion of visual aids for the SOT in the AC to be published in Q4 of 2025 and inclusion of unserviceability signage in the Part 139 MOS consistent with Annex 14 Amendment 18.