New multi-part AC for all-weather operations at aerodromes

Closed 12 Mar 2024

Opened 13 Feb 2024

Feedback updated 2 May 2024

We asked

This consultation asked people for feedback on a new draft multi-part advisory circular (AC) on all-weather operations (AWO) at aerodromes. This multi-part AC is intended to update and replace existing AC 139-19 v1.0 - All-weather operations at aerodromes. The consultation period ran from 13 February to 12 March 2024.

About this consultation
The original AC 139-19 was issued in May 2016. It cross-referred extensively with the version of the Part 139 Manual of Standards (MOS) (Aerodromes) in use prior to the post-implementation review of Part 139 of CASR. With the release of a new and current Part 139 MOS, much of that cross-referencing became invalid.

To ensure accuracy and relevance, we reviewed the AC and updated the cross-referencing. We also made some small changes to ensure that the AC provided guidance to assist operators of non-controlled aerodromes that support AWO.

The consultation asked respondents to give feedback on the new AC to ensure proposed guidance is suitable, clear and will work as intended.

You said

In total, there were 9 respondents to the consultation ranging from the national air navigation service provider – Airservices Australia, the Bureau of Meteorology, a specialist organisation in airport operations, staff training and management, an instrument flight procedure specialist and several individuals. Of the respondents, 5 consented to having their responses made public and 3 requested their submissions be confidential.

Summary of feedback
Three respondents provided detailed submissions. These submissions included feedback about unclear or inconsistent advice within the document, insufficient coverage of meteorological aspects, and references that appeared to oblige operators of non-controlled aerodromes to support AWO. The submissions from these respondents together with CASA's feedback/disposition are separately attached to this summary of consultation (SOC).

A respondent said CASA should provide all-weather operating minima specific for helicopters. These minima should recognise the unique capability of helicopters (* see below) compared to fixed wing aircraft, and allow helicopters to fly to lower minimums and have less minimum visibility requirements.

One respondent said the standards should allow a local competent observer for example, a town fire service, ambulance, police, or grounds person to be appointed to record automatic terminal information service (ATIS)-type information to be transmitted on a common traffic advisory frequency (CTAF). Another expressed concern about occurrences of departures and arrivals at uncontrolled and uncertified aerodromes in conditions well below the IFR minima. The respondent said the AC should stress that the AC guidance does not imply an ability to use an alternative set of criteria for unauthorised operations.

Finally, a respondent recommended that the AC includes guidance on instrument flight procedure design aspects relevant to AWO.For example: Lower operating speeds and ability to descend more slowly.

For example: Lower operating speeds and ability to descend more slowly.

We did

Next steps
We appreciate the feedback provided by respondents. For the detailed submissions, we included Annexes (* see below) to this SOC with those submissions and our response or disposition against each specific comment. We have also assessed all other responses to this consultation.

As a result of feedback, we have made a number of changes to the AC. In particular, we included guidance on meteorological and instrument flight procedure design aspects relevant to AWO. We have also clarified the guidance for aerodrome operators, particularly of non-controlled aerodromes, particularly to identify when the AC has relevance (for example when an aerodrome has an instrument flight procedure or is supporting take-off operations in visibility conditions less than 800 m).

Regarding the comment about appointing local competent observers to record ATIS information or equivalent, we consider that provision already exists through the UNICOM standards in Chapter 22 of the Part 139 MOS. However, we have added guidance within the AC in the section on aeronautical information to ensure this is recognised.

Concerning pilots conducting unauthorised operations in poor weather conditions, we have reviewed the AC and believe it does not encourage deviation from flying regulations or from safe flying practices. Accordingly, we believe no changes are necessary.

We now believe the AC will be fit for purpose  for providing best-practice guidance on AWO. Our next steps will be to finalise the draft AC and to publish it at the earliest opportunity.

* Annexes:
A.  Airports Plus submission with CASA response.
B.  Airservices Australia submission with CASA response.
C.  Bureau of Meteorology submission with CASA response.

Published responses

View submitted responses where consent has been given to publish the response.


We would like your feedback on the new draft multi-part advisory circular (AC) on all-weather operations (AWO) at aerodromes. This multi-part AC will replace existing AC 139-19 - All-weather operations on aerodromes and will complement AC 91-11 - Aeroplane low visibility operations - conduct and approvals.

An AWO involves an operation on an aerodrome (surface movement, take-off, departure, approach or landing) in conditions where visual reference is limited by weather conditions. AWOs include, but are not limited to, low visibility operations (LVO) and low visibility procedures (LVP). For example, an AWO involves aircraft departures from a non-controlled aerodrome, in reduced visibility, on a foggy day.

The purpose of this AC is to provide guidance and information to aerodrome operators and related service providers on best practices for managing all-weather operations, and for meeting legislative requirements. It expands on standards and guidance within Parts 139, 171 and 172 of the Civil Aviation Safety Regulations 1998 (CASR).

The new AC provides:

  • updated references to the Part 139 Manual of Standards (MOS) introduced in 2020
  • new guidance for operators of non-controlled aerodromes.

This AC will be of interest to:

  • aerodrome operators
  • aeronautical telecommunication service and radionavigation service providers
  • air traffic service providers
  • meteorological service providers
  • aircraft operators
  • pilots.

Why your views matter

Your feedback will help us make sure the proposed guidance is suitable, clear and will work as intended.

Documents for review

All documents related to this consultation are attached in the ‘Related’ section at the bottom of the overview page. They are:

  • Draft Multi-Part AC 139-05, AC 171-05 and AC 172-03 - v1.0
  • MS Word copy of online consultation for ease of distribution and feedback within your organisation.

Please submit your comments on the draft AC through the Consultation Hub using the survey provided. If you are unable to provide feedback this way, please contact us for advice through

Please read the AC document before providing your feedback.

What happens next

At the end of the response period, we will:

  • review all comments received
  • make responses publicly available on the consultation hub (unless you request your submission remain confidential)
  • publish a Summary of Consultation which summarises the feedback received and outlines any intended changes and next steps.

Feedback that improves the guidance will be incorporated into the final AC.


  • Aerodrome operator
  • Air operators
  • Air traffic service provider
  • Aviation Meteorology
  • Forecaster/Meteorological service provider
  • Certified aerodrome owner/operator
  • CASA aerodrome inspector
  • Aerodrome industry consultant


  • Airspace and infrastructure
  • Operational standards
  • Equipment standards