CASA 06/26 — Foreign Registered Aircraft in Australian Territory (Radio Altimeters) Direction 2026

Explanatory Statement

Civil Aviation Safety Regulations 1998

CASA 06/26 — Foreign Registered Aircraft in Australian Territory (Radio Altimeters) Direction 2026

Purpose

The purpose of CASA 06/26 — Foreign Registered Aircraft in Australian Territory (Radio Altimeters) Direction 2026 (the instrument) is to ensure that radio altimeters fitted to specified foreign aircraft that are used for low-visibility approaches in Australian territory comply with specified requirements. The instrument is required because the most recent of the fifth-generation (5G) wireless broadband systems in Australia are licensed to operate in a frequency band (3.7 – 4.0 GHz) that is near to the radio altimeter frequency band (4.2 – 4.4 GHz). Studies have shown that 5G transmissions in this band can interfere with the operation of radio altimeters. This issue is also faced by other National Aviation Authorities. The approach to this issue taken by the Civil Aviation Safety Authority (CASA) is consistent with the approach taken by the Federal Aviation Administration of the United States of America (FAA).

The instrument applies to operators of aircraft operating in Australian territory under a foreign air transport air operator’s certificate (AOC), or under a New Zealand AOC with ANZA privileges that is in force for Australia. The instrument directs these operators to ensure that the radio altimeters comply with requirements for tolerance to radio frequency interference set out in a specified Airworthiness Directive (AD) of the FAA that applies for the kind of aircraft (aeroplane or rotorcraft).

The instrument will commence on 1 April 2026 because interim measures imposed by the Australian Communications and Media Authority (ACMA) to mitigate the effects of 5G transmissions around airports are scheduled to end on 31 March 2026.

Legislation

Section 98 of the Civil Aviation Act 1988 (the Act) empowers the Governor-General to make regulations for the Act and in the interests of the safety of air navigation. Relevantly, the Governor-General has made the Civil Aviation Safety Regulations 1998 (CASR).

Subpart 11.G of CASR provides for CASA to issue directions in relation to matters affecting the safety of air navigation. Under paragraph 11.245(1)(a) of CASR, CASA may, by instrument, issue a direction about any matter affecting the safe navigation and operation of aircraft.

Subregulation 11.245(2) provides that CASA may issue such a direction if CASA is satisfied that it is necessary to do so in the interests of the safety of air navigation, if the direction is not inconsistent with the Act, and for the purposes of CASA’s functions.

Under regulation 11.250 of CASR, a direction ceases to be in force on the day specified in the direction or, if no day is specified, 1 year after the day it commences. Under regulation 11.255 of CASR it is an offence of strict liability (with a maximum penalty of 50 penalty units) to contravene a direction under regulation 11.245 that is applicable to the person.

Section 3 of the Act provides the following definitions of terms used in the instrument:

Australian territory means:

(a) the territory of Australia and of every external Territory; and

(b) the territorial sea of Australia and of every external Territory; and

(c) the airspace over any such territory or sea.

foreign registered aircraft means an aircraft registered:

(a) in a foreign country; or

(b) under a joint registration plan or an international registration plan.

in force for Australia, in relation to a New Zealand AOC with ANZA privileges, has the meaning given by section 3AA.

New Zealand AOC with ANZA privileges has the same meaning as in section 2 of the Civil Aviation Act 1990 of New Zealand.

The Civil Aviation Act 1990 of New Zealand has been repealed. Section 5 of the Civil Aviation Act 2023 of New Zealand provides the following definition of the term used in the instrument:

New Zealand AOC with ANZA privileges means an authorisation granted under section 91.

Part 1 of the CASR Dictionary provides the following definitions of terms used in the instrument:

foreign air transport AOC means an AOC that authorises the operation of an aircraft for a foreign air transport operation.

low-visibility approach means an approach using minima for a runway that are below the category I precision approach minima for the runway published in the AIP.

Aeronautical Information Publication or AIP has the same meaning as in the Air Services Regulations 2019.

Legislation Act 2003

Under subsection 14(1) of the Legislation Act 2003 (the LA), a legislative instrument may make provision in relation to matters by applying, adopting or incorporating provisions of an Act or disallowable legislative instrument as in force at a particular time or as in force from time to time. A legislative instrument may also make provision in relation to matters by applying, adopting or incorporating any matter contained in any other instrument or writing as in force at, or before, the time the legislative instrument commences. Under subsection 14(2), unless the contrary intention appears, the legislative instrument may not make provision in relation to a matter by applying, adopting or incorporating any matter contained in an instrument or other writing as in force or existing from time to time. However, subsection 98(5D) of the Act provides that, despite section 14 of the LA, a legislative instrument made under the Act or the regulations may apply, adopt or incorporate any matter contained in any instrument or other writing as in force or existing from time to time, even if the other instrument or writing does not yet exist when the legislative instrument is made.

Background

Radio altimeters perform a critical function during instrument approach operations and need to operate reliably. They are the only instruments on board an aircraft that accurately measure its height above the underlying terrain and obstacles, providing data required for the aircraft’s safety to the flight crew and other aircraft systems.

As mentioned above, radio altimeters operate in the 4.2 – 4.4 GHz radio frequency band and the most recent of the 5G wireless broadband systems in Australia are licensed to operate in a nearby band (i.e. 3.7 – 4.0 GHz). Studies have shown that 5G transmissions in this band can interfere with the operation of radio altimeters. The interference can result in intermittent operation, false data and indications, or system failure.

The situation is most critical for aircraft conducting instrument approach procedures (IAPs) under low-visibility conditions. The risks of radio altimeters being impaired during these operations include nuisance alerts and/or a failure to alert, increased flight crew workload, aborted landings (go-arounds) and, in the worst case, accidents.

The instrument approach operations determined to be reliant on radio altimeters are:

• Instrument Landing System Category II and III (ILS Cat II and III)
• Special Authorisation Category I and II (SA Cat I and II).

These operations are known as low-visibility approaches.

When ACMA granted new licences in the 3.7 – 4.0 GHz band to 5G wireless broadband operators, it imposed conditions to mitigate the effects of 5G transmissions on radio altimeters. However, these measures are scheduled to end on 31 March 2026.

The protective measures imposed by ACMA consisted of:

• exclusion zones surrounding runways where mobile communication stations are not allowed to be installed
• restricted zones, covering the final approach path from a height of 2 000 ft, where the signals from mobile communication transmitters need to be below power levels shown to affect the operation of radio altimeters.

As at the commencement of the instrument, further information regarding the protective measures imposed by ACMA is available on the ACMA website.

Radio altimeters need to operate reliably in the presence of 5G transmissions, both before and after these protective measures are removed. To this end, CASA issued media statements in October 2024 advising aircraft operators of the need to ensure radio altimeters comply with FAA ADs prior to the protective measures being withdrawn. Then in 2025, CASA published, for consultation, a draft of this instrument, together with a draft of the Parts 91, 121, 133 and 135 Manuals of Standards Amendment Instrument 2026 (the MOS amendments instrument).

The MOS amendments instrument imposes the requirement to comply with the FAA AD performance requirements for radio altimeters installed on aircraft used for low-visibility approaches on operators of Australian aircraft operating in Australian territory.

There is currently no recognised international standard for radio altimeters which will enable them to operate without any protections from 5G wireless broadband stations (5G stations). The FAA AD performance requirements represent the most protective internationally-recognised technical standard currently available.

The requirements imposed by the instrument (and the MOS amendments instrument) are expected to be reviewed once new global standards for radio altimeters are finalised. These new international standards are expected to be promulgated in 2027. CASA anticipates that the requirements imposed by the instrument will remain in force until such time as equipment compliant with this standard becomes readily available. It is expected that radio altimeters built to the new international standards will be more resilient to external radio frequency emissions than currently available models.

Overview of instrument

The instrument issues directions to the operators of the following kinds of foreign aircraft:

• foreign registered aircraft operating in Australian territory under a foreign air transport AOC
• foreign registered aircraft operating in Australian territory under a New Zealand AOC with ANZA privileges that is in force for Australia.

The directions require these aircraft operators to ensure that each radio altimeter fitted to an aircraft used for the conduct of a low-visibility approach in Australian territory complies with the specifications for radio interference tolerance in a specified FAA AD. An exception to this applies to the operator of an aircraft that is being used for the conduct of a low-visibility approach at an aerodrome that is included in a CASA-maintained written list of aerodromes. The purpose of this arrangement, which is in force until the end of 31 March 2027, is to provide aircraft operators with additional time to comply with the directions.

To protect aviation safety, CASA intends to list an aerodrome only if there are no 5G stations operating in notification zones defined by ACMA for the aerodrome. The list is to be maintained by CASA for the purpose of the instrument and published on the CASA website.

Low-visibility approaches are the following IAPs:

• Instrument Landing System Category II and III (ILS Cat II and III)

• Special Authorisation Category I and II (SA Cat I and II).

The relevant FAA ADs are:

• AD 2023-10-12 — for aeroplanes
• AD 2023-11-07 — for rotorcraft.

These ADs are incorporated by the instrument as existing on their date of publication in the Federal Register of the United States Government.

The FAA AD performance requirements do not apply to radio altimeters fitted to aircraft used for the conduct of Required Navigation Performance – Approval Required (RNP-AR) IAPs (see under the heading Consultation below).

CASA has assessed the impact of the instrument on aviation safety and considers that the proposed amendments are necessary to maintain safety during a critical phase of an aircraft’s approach and landing at aerodromes at which 5G stations are operating.

Documents incorporated by reference

In accordance with paragraph 15J(2)(c) of the LA, the following table contains a description of the documents incorporated by reference into the legislative instrument, the organisation responsible for each document and how they may be obtained. The table also states how the document is incorporated.

Content of instrument

Section 1 names the instrument.

Section 2 sets out the duration of the instrument. The instrument commences on 1 April 2026 and is repealed at the end of 31 March 2029.

Section 3 provides that the instrument applies to the operator of an aircraft if the aircraft is a foreign registered aircraft operating in Australian territory under a foreign air transport AOC, or is a foreign registered aircraft operating in Australian territory under a New Zealand AOC with ANZA privileges that is in force for Australia.

Section 4 sets out directions that apply to the operator of aircraft.

Subsection 4(1) provides that the operator must ensure that each radio altimeter fitted to an aeroplane used for the conduct of a low-visibility approach complies with the requirements for tolerance to radio frequency interference specified for a “radio altimeter tolerant airplane” in FAA AD 2023-10-02 as existing on 26 May 2023.

A note below the subsection explains the definition of “radio altimeter tolerant airplane” in FAA AD 2023-10-02. A second note explains that 26 May 2023 is the date FAA AD 2023‑10-02 was published in the Federal Register of the United States Government.

Subsection 4(2) provides that the operator must ensure that each radio altimeter fitted to a rotorcraft used for the conduct of a low-visibility approach complies with the requirements for tolerance to radio frequency interference specified for a “radio altimeter tolerant rotorcraft” in FAA AD 2023-11-07 as existing on 22 June 2023.

A note below the subsection explains the definition of “radio altimeter tolerant rotorcraft” in FAA AD 2023-11-07. A second note explains that 22 June 2023 is the date FAA AD 2023‑11-07 was published in the Federal Register of the United States Government.

Subsection 4(3) provides that the preceding subsections do not apply to an operator of an aircraft used for the conduct of a low-visibility approach at an aerodrome that is included in a written list of aerodromes, as the list exists from time to time, that is maintained by CASA for the purposes of the instrument and published on the CASA website. CASA intends to only list an aerodrome if there are no 5G stations operating in the notification zones defined by ACMA for that aerodrome.

Subsection 4(4) provides that subsection 4(3) is in force until the end of 31 March 2027.

Legislation Act 2003

Paragraph 98(5A)(a) of the Act provides that CASA may issue instruments in relation to matters affecting the safe navigation and operation or the maintenance of aircraft. Additionally, paragraph 98(5AA)(a) of the Act provides that an instrument issued under paragraph 98(5A)(a) is a legislative instrument if the instrument is expressed to apply in relation to a class of persons and paragraph 98(5AA)(b) of the Act provides that an instrument issued under paragraph 98(5A)(a) is a legislative instrument if the instrument is expressed to apply in relation to a class of aircraft.

The instrument directs a class of persons in relation to the operation of a class of aircraft. The instrument is, therefore, a legislative instrument and is subject to tabling and disallowance in the Parliament under sections 38 and 42 of the LA.

Sunsetting

Part 4 of Chapter 3 of the LA (the sunsetting provisions) does not apply to the instrument because the instrument relates to aviation safety and is made under CASR (item 15 of the table in section 12 of the Legislation (Exemptions and Other Matters) Regulation 2015).

However, this instrument will be repealed at the end of 31 March 2029, which will occur before the sunsetting provisions would have repealed the instrument if they had applied. Any renewal of the instrument will be subject to tabling and disallowance in the Parliament under sections 38 and 42 of the LA. Therefore, the exemption from sunsetting does not affect parliamentary oversight of this instrument.

Consultation

Consultation under section 17 of the LA was undertaken on a draft of the instrument before the instrument was made. The consultation opened on 7 July 2025 and closed on 3 August 2025 and was undertaken at the same time as consultation on the draft MOS amendments instrument.

Fourteen responses were received. Of the 14 responses received:

• 9 responses were sent on behalf of airlines
• 4 responses were received from individuals
• 1 was from an aircraft manufacturer.

As a result of the consultation feedback, and further risk analysis of the safety impact of 5G transmissions on the conduct of RNP-AR IAPs, CASA removed the requirement in the draft instrument for operators of aircraft fitted with radio altimeters that are used for RNP-AR IAPs from having to ensure that the radio altimeters comply with the FAA performance requirements. This is consistent with the approach taken by the FAA, which revised its ADs to remove RNP-ARs from the list of operations considered susceptible to 5G transmissions.

CASA also amended the draft instrument to enable aircraft operators to conduct low-visibility approaches at aerodromes included in a CASA-maintained list of aerodromes without having to comply with the new requirements. This arrangement will provide aircraft operators with additional time to comply with the new rules. For further information regarding this arrangement, see under the headings Overview of instrument and Content of instrument.

CASA is satisfied that no further consultation is appropriate or reasonably practicable for this instrument for section 17 of the LA.

Sector risk, economic and cost impact

Subsection 9A(1) of the Act states that, in exercising its powers and performing its functions, CASA must regard the safety of air navigation as the most important consideration. Subsection 9A(3) states that, subject to subsection (1), in developing and promulgating aviation safety standards under paragraph 9(1)(c), CASA must:

(a) consider the economic and cost impact on individuals, businesses and the community of the standards; and

(b) take into account the differing risks associated with different industry sectors.

The cost impact of a standard refers to the direct cost (in the sense of price or expense) which a standard would cause individuals, businesses and the community to incur. The economic impact of a standard refers to the impact a standard would have on the production, distribution and use of wealth across the economy, at the level of the individual, relevant businesses in the aviation sector, and the community more broadly. The economic impact of a standard could also include the general financial impact of that standard on different industry sectors.

The economic and cost impact of the instrument has been determined by:

(a) the identification of individuals and businesses affected by the instrument; and

(b) consideration of how the requirements to be imposed on individuals and businesses under the instrument will be different compared to existing requirements; and

(c) a valuation of the impact, in terms of direct costs, on individuals and businesses affected by the instrument to comply with the different requirements. This valuation is consistent with the principles of best practice regulation of the Australian Government; and

(d) a valuation of the impact the different requirements would have on the production, distribution and use of wealth across the economy, at the level of the individual, relevant businesses in the aviation sector and the community more broadly; and

(e) consideration of community impacts, beyond those direct impacts on individuals and businesses affected by the instrument, that are relevant if the instrument were to result in flow‑on effects to other aviation businesses, or local non-aviation businesses that experience a change in their activity due to the instrument.

The instrument is required because the most recent 5G wireless broadband systems in Australia are licensed to operate in a frequency band near to the radio altimeter frequency band and can interfere with radio altimeters. This is an issue faced by other National Aviation Authorities and the instrument is consistent with the approach taken by the FAA.

The requirements of the instrument apply to operators of specified foreign aircraft operating in Australian territory. Under the instrument, radio altimeter upgrades are only required for radio altimeters fitted to aircraft conducting low-visibility approaches (only available at Melbourne, Sydney, Canberra and Perth airports (and Western Sydney International when it begins operations)). Aircraft operators can choose to avoid the direct costs of upgrading by not conducting low-visibility approaches. However, this may incur indirect costs such as increased fuel carriage or diversions to airports other than the desired destination.

Many radio altimeters fitted to aircraft already meet the FAA AD requirements, as this is a requirement for air transport aircraft that fly to the United States of America. New aircraft are likely to be supplied with radio altimeters that are already compliant with the relevant FAA AD.

CASA has estimated that the average cost to ensure compliance with the FAA AD requirement is $70 000 for any aircraft that is not already compliant.

Impact on categories of operations

The operators of foreign aircraft to which the instrument applies will be unable to use some of their aircraft for low-visibility approaches at those airports mentioned above that have facilities for low-visibility instrument approaches if the radio altimeters of those aircraft do not comply with the new requirements. However, many foreign aircraft operators already have radio altimeters that comply with the FAA AD requirements to fly to the United States of America. Also, the alleviation granted under the instrument until 31 March 2027 for aircraft conducting low-visibility approaches at listed airports will enable them to operate at those airports while updating their radio altimeters to comply with the directions.

Impact on regional and remote communities

The instrument would have no negative impact on regional and remote communities.

Office of Impact Analysis (OIA)

An impact analysis (IA) is not required in this case, as the instrument is covered by a standing agreement between CASA and the OIA under which an IA is not required for directions (OIA reference number OIA23-06252).

Statement of Compatibility with Human Rights

The Statement of Compatibility with Human Rights at Attachment 1 has been prepared in accordance with Part 3 of the Human Rights (Parliamentary Scrutiny) Act 2011.

Making and commencement

The instrument has been made by the Director of Aviation Safety, on behalf of CASA, in accordance with subsection 73(2) of the Act.

The instrument commences on 1 April 2026 and is repealed at the end of 31 March 2029.

Attachment 1

Statement of Compatibility with Human Rights

Prepared in accordance with Part 3 of the
Human Rights (Parliamentary Scrutiny) Act 2011

CASA 06/26 — Foreign Registered Aircraft in Australian Territory (Radio Altimeters) Direction 2026

This legislative instrument is compatible with the human rights and freedoms
recognised or declared in the international instruments listed in section 3 of the
Human Rights (Parliamentary Scrutiny) Act 2011.

Overview of the legislative instrument

The purpose of the legislative instrument is to ensure that radio altimeters fitted to specified foreign aircraft that are used for low-visibility approaches in Australian territory are “5G‑tolerant”. The instrument directs operators of such aircraft to ensure that the radio altimeters comply with requirements for tolerance to radio frequency interference set out in a specified Airworthiness Directive (AD) of the Federal Aviation Administration of the United States of America (FAA) that applies for the kind of aircraft (aeroplane or rotorcraft).

The instrument is required because for safety reasons radio altimeters need to operate reliably in the presence of fifth-generation (5G) wireless broadband transmissions. The instrument will commence on 1 April 2026 because interim measures imposed by the Australian Communications and Media Authority (ACMA) to mitigate the effects of 5G transmissions around airports are scheduled to end on 31 March 2026. The requirements are expected to be reviewed once new global standards for radio altimeters are developed.

Although the instrument commences on 1 April 2026, it excludes operators from the obligations imposed by the directions until 31 March 2027 if the aircraft is being used for the conduct of a low-visibility approach at an aerodrome included in a published list of aerodromes that is maintained by CASA. CASA intends to list an aerodrome only if there are no 5G wireless broadband stations operating in notification zones defined by ACMA for the aerodrome.

The instrument applies to operators of aircraft operating in Australian territory under a foreign air transport air operator’s certificate (AOC), or under a New Zealand AOC with ANZA privileges that is in force for Australia.

The specified FAA ADs are:

• AD 2023-10-02 — for aeroplanes
• AD 2023-11-07 — for rotorcraft.

Human rights implications

The instrument promotes the right to life in Article 6 of the International Covenant on Civil and Political Rights by protecting aviation safety during the conduct of low-visibility approaches for landing of aircraft.

Conclusion

This legislative instrument is compatible with human rights.

Civil Aviation Safety Authority