Tranche 2 - Proposed new Part 121 MOS – Australian Air Transport Operations - Larger Aeroplanes - (CD 2010OS)

Closed 3 Aug 2020

Opened 3 Jul 2020


Part 121 of the Civil Aviation Safety Regulations 1998 (CASR) – Australian air transport operations – larger aeroplanes, and its Manual of Standards (MOS) will contain the specific safety rules for air transport operations in larger aeroplanes.

The rules in this consultation will apply to persons and operators who conduct multi-engine aeroplane air transport operations (including passenger, cargo and medical transport operations) with a maximum operational passenger seating capacity of more than nine seats or a maximum take-off weight of more than 8,618 kgs. The proposed rules in this consultation do not affect the single-engine aeroplanes operated under Subpart 121.Z.

The standards in the Part 121 MOS are derived mainly from existing standards which are in the Civil Aviation Regulations 1988 (CAR), multiple Civil Aviation Orders (CAO) and various instruments. Where appropriate for Australian operations, these standards have been aligned to international best practice and the standards and recommended practices published by the International Civil Aviation Organization (ICAO).

Consultation on the Part 121 MOS is being conducted in three tranches that are likely to overlap. This is the second tranche and covers the following chapters and topics:

  • Chapter 9 – performance
  • Chapter 12 – flight crew training and checking
  • Chapter 13 – cabin crew training and checking
  • Chapter 14 – emergency evacuation demonstrations and procedural requirements.

Key changes at a glance

This public consultation seeks feedback on:

  • proposed amendments to Part 121 regulations which were made in 2018 and commence in December 2021
  • tranche 2 of the proposed Part 121 MOS
  • any additional feedback on tranche 1 not provided as part of the earlier tranche 1 consultation activity.

There are a number of differences between current requirements and those requirements contained in this draft of the Part 121 MOS. CASA has deliberately designed the majority of these requirements to be compatible with existing operator practices. The changes relate to:

  • Introduction of a requirement to extinguish a fire during flight crew and cabin crew initial training.
  • Introduction of a requirement for flight crew and cabin crew, during initial training and 3-yearly training, to conduct a fire drill in a smoke-filled (or simulated smoke-filled) environment.
  • Introduction of outcome-based standards for training facilities and training devices (not including flight simulators and flight training devices which are covered by Part 60 of CASR).
  • Alleviation from the existing CAO 20.11 requirements to conduct all safety and emergency training annually – these requirements are now split into annual and 3-yearly requirements.

The regulation changes outlined in this consultation, propose the deletion of six regulations and changes to (15) regulations and the addition of one regulation. All these changes, aside from the proposed additional regulation and its two interrelated regulations proposed to be deleted, are legally technical amendments and are not amendments that change the aviation safety outcome or standard. The technical amendments are included in this consultation to ensure the industry is aware of the possible changes and have an opportunity to provide feedback. However, it should be noted that the exact phrasing of the changes may differ from those outlined in this consultation. The proposed regulation amendments relevant to tranche 1 are outlined in the tranche 1 consultation documents and amendments relevant to tranche 3 will be consulted during that consultation activity.

Consultation on the rest of the Part 121 MOS

The remaining five chapters of the MOS not yet released for comment will be the subject of a future public consultation. During this consultation and the next there is an opportunity to provide additional comments on earlier tranches.

Subject to further discussions with the Aviation Safety Advisory Panel’s Part 121 Technical Working Group (TWG) and the progress of legal drafting, CASA is aiming is to conclude consultation on the Part 121 MOS by the end of August 2020. This will allow time to analyse all the feedback, discuss changes with the TWG and undertake the administrative processes associated with making the MOS into law, and amending any regulations where this is necessary.

How Part 121 works in conjunction with Part 91 general operating and flight rules

Regulation 91.035 contains a table that 'turns off' or disapplies certain Part 91 requirements in favour of Part 121 requirements. In relation to air transport operations, certain Part 91 rules are turned off because either the Part 121 rules have specified a higher safety standard or the requirement to hold an AOC has put in place system-based safety defences that achieve the safety standards by alternative means.

How Part 121 works in conjunction with Part 119 (air transport certification requirements)

Part 119 outlines the rules for applicants and holders of Air Operators’ Certificates (AOCs). Part 121 operations are not authorised to be conducted unless an operator meets the requirements in Part 119 for the issue of an Australian air transport AOC. Generally, Part 119 of CASR will specify the organisational requirement and the specific air transport operational Part (i.e. Part 121 in this case) will state the operational standard. Both CASR parts must be read in conjunction to gain a full understanding of a topic. One example of this kind of interaction is:

  • Part 119 requires an Australian air transport operator to have a training and checking system and specifies the broad requirements and characteristics of that system; but
  • Subparts 121.N and 121.P specify the operational requirements for that system specific to Part 121 operators and include the detailed rules for the training and checking of an operator’s flight crew members and cabin crew members.

Overlap with Part 135 - Australian air transport operations – smaller aeroplanes

Subpart 121.Z specifies that certain single-engine aeroplanes used in air transport operations must comply with Part 135 of CASR and a small number of additional requirements. Outside of the regulations contained in subpart 121.Z, none of the other regulations within Part 121 or any of the Part 121 MOS content applies to the operation of these aeroplanes during an air transport operation.

Previous consultations

CASA publicly consulted the Part 121 regulations in 2015. An indicative only version of the Part 121 MOS accompanied that consultation. Multiple industry working group sessions provided feedback on the Part 121 regulations prior to that consultation but did not provide detailed feedback on the indicative MOS. CASA again conducted a similar public consultation of the regulations in 2018 due to significant changes to match the new Part 91. The indicative MOS was again provided and similar to previous iterations, the new TWG did not provide detailed feedback. On isolated occasions in early and late 2019, CASA engaged with the TWG on specific MOS topics that are not part of this first tranche. In the second quarter of 2020, CASA and the TWG have frequently discussed chapters 13 and 14 of tranche 2 but have had minimal discussion on chapters 9 and 12. A large number of individual alterations were made to the draft MOS as a result of these consultations.

Why your views matter

This consultation seeks feedback on the proposed Part 121 MOS and a number of proposed changes to the Part 121 regulations made into law in December 2018 (where these are not related to tranches 1 or 3 of the MOS). The survey has been designed to give you the option to provide feedback on the survey in its entirety or to provide feedback on the policy topics applicable to you.

We are consulting to ensure that the proposed new standards in the Part 121 MOS are clearly articulated and will work in practice. Your feedback will make a valuable contribution to our standards development and making process and help to inform any future regulatory change.  Comments on the CD 2010OS should be submitted through the online response form.

Documents for review and reference

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

  • Summary of proposed change on CD 2010OS, which provides background on the proposed standards
  • Exposure Draft Part 121 MOS – new chapters 9, 12, 13 and 14 (for completeness the draft also includes the tranche 1 chapters)
  • Civil Aviation Safety Amendment (Part 121) Regulations 2018 (F2018L01784)
  • Civil Aviation Safety Amendment (Operations Definitions) Regulations 2019 (F2019L00557)
  • Civil Aviation Safety Amendment (Part 91) Regulations 2018 (F2018L01783)
  • Unofficial consolidated CASR Dictionary – (combines the official CASR Dictionary and the official amendment regulation incorporating the operations definitions)
  • MS Word copy of this consultation for ease of distribution and feedback within your organisation. 

Note: The Word document is not to be used as an emailed submission, unless there are extenuating circumstances and this form of submission has been agreed to by the consultation project lead.

Please read the Summary of proposed change (CD 2010OS) consultation document before providing your feedback in the online survey.

CASA highly recommends the use of the ‘unofficial consolidated CASR dictionary’. Some minor differences exist between this document and the ‘Operations Definitions’ regulation however these are isolated to the sport and recreation sectors and do not affect any of the content of this proposed MOS.

Information about how we consult and how to make a confidential submission is available on the CASA website.

To be notified of any future consultations, you can subscribe to our consultation and rulemaking mailing list .

File upload option

Note: CASA can no longer offer the option to upload files because of the potential risk of malware.

Using an iPad

If you are using an iPad to complete the survey you will be asked to 'download the relevant PDF'. Depending on the software you have on your iPad you may need to download the free viewer to review the single document PDF files. Where a file is a 'multi-file or portfolio PDF you will need to source the Adobe free view - available from iTunes.

What happens next

At the end of the response period for public comment, we will review each comment and submission received. All comments will be considered. We will make all submissions publicly available on the CASA website, unless you request your submission remain confidential. Relevant feedback that improves upon the proposed standards and is consistent with the regulations and other CASA policy, will be incorporated into the final MOS.

At the conclusion of the third tranche of consultation, we will publish a Summary of Consultation which summarises the feedback received across all three tranches, outlines any intended changes and details the next steps for the MOS and the proposed regulation changes. The Part 121 MOS will come into effect on 2 December 2021 when the Part 121 regulations also start.

Information about how we consult and how to make a confidential submission is available on the CASA website.

To be notified of any future consultations, you can subscribe to our consultation and rulemaking mailing list .


  • CASA Staff
  • Aerodrome operator
  • Air operator
  • Pilots
  • Traveling public/passengers
  • Operations Control/Flight Dispatch
  • Aircraft owner/operator


  • Air travel
  • Human factors
  • Safety management systems
  • Operational standards
  • Cabin safety
  • Airworthiness/maintenance (CAR 30 and CASR Part 145 maintenance orgs)
  • Training and checking systems