Commonwealth legislation

AD/RAD/21 - Instrument Landing Systems (ILS) Instrumentation

RepealedCTH

This Act has been repealed and is no longer in force. It is retained for historical reference.

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

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What this does: This safety rule prevents aircraft navigation displays from mixing up landing signals. It requires that when an instrument shows both horizontal position (localiser) and vertical descent path (glideslope) guidance, both signals must come from the same ground-based Instrument Landing System (ILS). This stops the dangerous scenario where a pilot might follow horizontal directions for one runway while following vertical directions for a different one.

Who it affects: Aircraft with ILS equipment installed or modified after 15 April 1969.

Why it matters: During landing—especially in poor visibility when pilots rely entirely on instruments—mixing signals from different runways could send the aircraft off course or into the ground. This "cross-system" error was a known risk in early integrated flight displays.

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AD/RAD/21 - Instrument Landing Systems (ILS) Instrumentation

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source Radio Communication and Navigation Equipment

AD/RAD/21 Instrument Landing Systems (ILS) Instrumentation 3/69

Applicability: Airborne ILS installations completed or modified after 15 April 1969.

Requirement: Localiser and Glideslope information displayed simultaneously on any one indicator shall always relate to the same Instrument Landing System.

Compliance: Before 15 April 1969.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.