Proposal to amend the aeroplane TAWS rules - (CD 2311OS)

Closed 24 Oct 2023

Opened 26 Sep 2023

Feedback updated 20 Dec 2023

We asked

This consultation was opened on 26 September 2023 and closed on 24 Oct 2023. It asked people to consider a proposal to amend the TAWS fitment rules for Part 135 aeroplanes carrying between 9 and 13 passengers to allow the fitment of TAWS-Class B equipment with a visual terrain display (called a TAWS-Class B+) instead of the currently required TAWS-Class A.

You said

CASA received a total of 17 submissions to this consultation. Twelve responses (70%) were from organisations or operators and 5 (30%) were from individuals. Eight respondents (47%) consented to have their comments attributed to them including publication on the CASA Consultation Hub.

Eleven respondents (64%) agreed that the proposed amendments achieved the policy aim. Two respondents (12%) agreed with the proposal with changes in subject areas that did not directly relate to the question asked by the consultation.

Four (24%) respondents disagreed with the proposal and provided commentary and suggestions, with all these comments concerning topics not canvassed by the consultation. There was no response received that indicated a preference for the existing policy of requiring TAWS A for these aircraft to be retained.

Feedback from those respondents who consented to having their responses published are at Appendix A.

Summary of feedback

Of the 11 respondents who supported the proposal, 9 did not provide significant commentary. One respondent supported the proposal and encouraged CASA to expedite the regulatory amendment process to avoid uncertainty amongst aircraft owners. One respondent supported the proposal and raised an issue concerning how the determination of a suitable visual display of terrain would be carried out. This constituted 64% support for the proposal.

One respondent who agreed with the proposal raised the issue of who would determine the compliance status of any visual display system intended to meet the requirements of TSO C151c, as this information may not be present in manufacturers data. CASA intends to publish advice to operators who wish to take advantage of the TAWS-Class B+ option how they can make this determination.

One respondent who agreed with the proposal mentioned that some operators may still require time to transition to the new TAWS rules. CASA considers that ample time has been allowed for in the transitional instruments and it is not intended to extend these deadlines.

Two respondents agreed with the proposal with changes. Of these, 1 respondent suggested that the requirement for TAWS for VFR operations was excessive and unwarranted and should be reversed. This commentary did not directly relate to the proposal.

CASA's position is that in order to maintain appropriate safety standards when allowing single pilot Part 135 operations carrying more than 9 passengers, CASA was advised by the ASAP and TWG that a suitable mitigator for CFIT risks was to mandate TAWS for all operations. CASA is not considering amending this policy position at this time.

One other respondent who agreed with the proposal with changes suggested that the existing 13-seat limit expressed in CASA EX97-22 should revert to 9 seats for all Part 135 operations. This commentary did not directly relate to the proposal.

CASA's position is that the overwhelming majority of the industry supported the concept of allowing the carriage of more than 9 passengers (in aircraft that were capable of this) in air transport operations under the Part 135 ruleset instead of the Part 121 ruleset due to the added compliance cost burden of the Part 121 rules. At this time, CASA is not considering amending this policy.

Of the 4 respondents who disagreed with the proposal, 1 suggested that CASA should review OEM certification levels, presumably with a view to requiring manufacturers to fit appropriate equipment. CASA has no ambit nor mechanism to influence OEM’s or foreign certification authorities with respect to aircraft equipment. CASA acknowledges the commentary provided by the respondent; however, considers that this suggestion is not feasible.

Another 2 respondents who did support the proposal provided commentary that CASA TAWS policy in general was excessively onerous and inappropriate. Some of this commentary demonstrated a lack of understanding of the intent and background of existing ICAO and other NAA TAWS policy and the operation of the CASA TAWS rules. One respondent suggested that CFIT accidents are correlated to the number of passengers carried and that this was the instigator for expanded TAWS requirements. One view was that the TAWS requirements should be related to the number of seats in the aircraft, not the number of passengers carried.

CASA regulations largely follow international practice where the TAWS rules operate to reduce both the likelihood of a CFIT accident (by mandating technical equipment requirements) and the consequence of such an accident should it occur (by setting upper limits of passengers on board). Previous consultations on the TAWS issue carried out in 2018 prior to the introduction of the FOR affirmed support for the CASA policy position as published in Part 135 of CASR.

CASA’s position on this matter is that the current consultation aims to seek approval for a proposal to refine the original rules and does not extend to contemplating that CASA amend its policy concerning TAWS fitment generally. CASA acknowledges the commentary provided by the respondents, however has no plans to further modify the TAWS rules.

One respondent who disagreed with the proposal suggested that the rules be amended to make piston and turbine powered aircraft with a seating capacity greater than 5 to be subject to the TAWS requirements. It should be mentioned that this proposal was raised in consultation with industry and the public prior to the introduction of the FOR as one of the options for the Part 135 rules and it was decided by CASA to not proceed with this alternative.

In relation to this matter CASA is in receipt of Recommendation 1 from the Coroner’s Court of Queensland findings in relation to the fatal accident at Lockhart River in March 2020 that states:

“The Civil Aviation Safety Authority to implement relevant regulation to mandate the fitment of TAWS for all small aeroplanes conducting air transport operations under IFR (and night VFR) where the aeroplane has a passenger carrying capacity of 6 or more regardless of whether the aeroplane is turbine or piston powered.”

CASA is reviewing this recommendation in line with its obligations and will be able to respond to this commentary when this review is complete.

We did

As a result of the support for the proposal from this consultation, CASA will implement this proposal by amending the legislation. CASA will address the issue raised in relation to how the Visual Terrain Display requirements are determined by the operator and will publish appropriate guidance in due course.

Published responses

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


We want your feedback on a proposed change to the rules on the fitment of Terrain Awareness and Warning Systems (TAWS) in small turbine-engine aeroplanes.

The consultation relates to Part 121 and 135 turbine-engine aeroplanes with a maximum take-off weight of 5700kg or less and that either:

  • have a maximum operational passenger seat configuration between 10-13 seats


  • carry 10 or more persons.

Under the new Part 121 and Part 135 of the Civil Aviation Safety Regulations 1998 (CASR), the TAWS requirement for certain aeroplanes was raised from a TAWS B+ system to TAWS A.

Feedback from the aviation community advised:

  • TAWS B+ with a detailed visual terrain display would only have small (if any) safety differences compared to TAWS A for aeroplanes with a maximum take-off weight of 5700kg or less
  • the projected cost of upgrading from the old TAWS B+ to TAWS A has increased dramatically since the new Part 121 and 135 rules were made in 2018.

In response to the feedback, we set up a working group to discuss the safety differential between different TAWS standards in the context of these aeroplanes and the contemporary costs associated with TAWS A fitment.

This resulted in a recommendation that the TAWS fitment policy for certain aeroplanes be changed from TAWS A to a new version of TAWS B+.

The proposed amendment would permit these aeroplanes to be fitted with either a TAWS A or a TAWS B equipped with a visual terrain display that provides the terrain-related information outlined in section 3.5 of Appendix 1 of Technical Standard Order (TSO)-C151c for a terrain display.

We are proposing to call it TAWS-Class B+ as distinct from the previous TAWS-B+ system.

The details of the proposed changes to the legislation are provided in the attached Summary of Proposed Change.

Your feedback on these changes will help us check that the amended policy achieves an acceptable level of aviation safety for crew and passengers.

Please note that we are not proposing changes to the fitment requirement deadline of 2 December 2023.

Previous consultations

Prior to the release of this Summary of Proposed Change, a working group provided advice to CASA. Earlier consultations occurred in 2018 and between 2009 and 2012.

Why your views matter

Your feedback will help us make sure the proposed requirements are suitable, the final legislation is clear and will work as intended.

Please submit your comments using the survey link on this page.

If you are unable to provide feedback via the survey link, please email for advice.

Documents for review

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

  • Summary of proposed change on CD 2311OS, which provides background on the proposed standards
  • MS Word copy of online consultation for ease of distribution and feedback within your organisation.

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.

All comments received on the proposal will be considered. Relevant feedback that improves upon the proposal will be incorporated into the final legislation changes.


  • Air operators
  • Pilots
  • Aircraft owner/operator
  • Passengers travelling on small commercial turbine aeroplanes


  • Air travel
  • Operational standards
  • Airworthiness/maintenance (CAR 30 and CASR Part 145 maintenance orgs)
  • Equipment standards