{"id":"F2006B06522","name":"AD/RAD/68 Amdt 2 - Mode C Transponder Altitude Checks","slug":"ad-rad-68-amdt-2-mode-c-transponder-altitude-checks","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48140,"registerId":"commonwealth-F2006B06522-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RAD/68 Amdt 2 - Mode C Transponder Altitude Checks","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \n![](image.002.png)  \nRadio Communication and Navigation Equipment\n\nAIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive AD/RAD/68 Amdt 2.\n\n![](image.002.png)  \n\nAD/RAD/68\n\nAmdt 2\n\n  \nMode C Transponder Altitude Checks 6/2000\n\nRequirement: CANCELLED.\n\nBackground: This Directive was based on United States Federal Aviation Administration (FAA) AD 99-23-22R1. The FAA AD was rescinded with effect 20 April 2000 as the FAA has determined that repetitive tests are unnecessary and they increase component wear.\n\n![Signature of Eugene Paul Holzapfel Delegate of the Civil Aviation Safety Authority](image.003.png)  \n\nEugene Paul Holzapfel\n\nDelegate of the Civil Aviation Safety Authority 2 May 2000\n\n![](image.002.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 17 May 2000.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The instrument changes the scope of regulation by removing a previously mandated requirement. AD/RAD/68 Amdt 2's obligation for repetitive Mode C transponder altitude checks has been cancelled (Requirement: CANCELLED). The stated reason is reliance on the FAA's rescission of its corresponding AD on 20 April 2000, which the background says was based on a determination that repetitive tests were unnecessary and increased component wear (Background)."},"complexity_factors":["Single, discrete legal action (revocation/cancellation) rather than a multi-part regulatory regime","Short text with explicit statement of cancellation (Requirement: CANCELLED)","Decision relies on external regulator's prior action (FAA rescission) rather than introducing new technical criteria","No new compliance procedures, transitional rules, or technical specifications included","Limited number of stakeholders directly affected (operators of Mode C transponder-equipped aircraft)"],"plain_english_summary":"### What this instrument does\n\nThis airworthiness directive revokes (cancels) a previous safety requirement that required repetitive checks of Mode C transponder altitude reporting. The document states the formal action as: \"Requirement: CANCELLED.\" (Requirement line). The revocation was made by a CASA delegate and is dated 2 May 2000 (signature line) and notified in the Commonwealth Gazette on 17 May 2000 (notification line).\n\n### Who this affects\n\n- Aircraft owners and operators who would have been required to carry out the repetitive Mode C transponder altitude checks under AD/RAD/68 Amdt 2. (Requirement line)\n- The Civil Aviation Safety Authority (CASA) as the administrator of airworthiness directives, which decided to revoke the requirement. (signature line)\n\n### Why it matters (source claims and mechanical effects)\n\n- The background given for the revocation is that the directive was originally based on a United States FAA airworthiness directive (FAA AD 99-23-22R1) and that the FAA rescinded its AD effective 20 April 2000 because it \"determined that repetitive tests are unnecessary and they increase component wear.\" (Background line).\n\nMechanically, revoking the AD removes the regulatory obligation created by that AD. Concretely:\n- Operators are no longer required by this AD to perform the repetitive Mode C altitude checks that AD/RAD/68 Amdt 2 had mandated. (Requirement: CANCELLED)\n- The stated reason for removing the requirement is an external regulator's reassessment (FAA) that the tests provided insufficient benefit relative to their cost in component wear. (Background)\n\n### Trade-offs, incentives and implementation points (grounded to the text)\n\n- Who pays: While the directive was in force, operators would have borne the cost (time, labour, parts replacement induced by test-driven wear) of the repetitive checks. Revocation removes that mandated expense for those operators. (Requirement: CANCELLED; Background)\n\n- Incentives and behaviour changes: Removing the mandatory tests reduces the regulatory pressure to perform frequent checks; operators may choose not to perform them unless other rules, manuals, insurers, or commercial safety practices still require them. (Requirement: CANCELLED)\n\n- Costs and substitution effects: The background states repetitive tests increase component wear. If operators stop mandated repetitive tests, that reduces the component-wear cost but also reduces the frequency of a monitoring activity. The instrument records the FAA's judgment that the monitoring benefit was unnecessary relative to the wear cost; the text does not quantify either side. (Background)\n\n- Compliance burden and discretion: The revocation is a single, clear change in legal obligation by CASA (signed by the CASA delegate). It transfers discretion back to operators and any other applicable rules outside this AD; the document itself does not create new compliance tasks. (signature line; Requirement)\n\n- Implementation risk and opportunity cost: The AD text records reliance on the FAA rescission as the reason for cancelling the Australian AD. The document does not set out additional technical analysis, monitoring requirements, or transitional provisions; it simply cancels the prior requirement. That means the decision depends on the FAA's reassessment rather than on new material published in this AD. (Background; Requirement)\n\n### Source citations\n\n- Requirement: \"Requirement: CANCELLED.\" (Requirement line)\n- Background explanation: \"This Directive was based on United States Federal Aviation Administration (FAA) AD 99-23-22R1. The FAA AD was rescinded with effect 20 April 2000 as the FAA has determined that repetitive tests are unnecessary and they increase component wear.\" (Background line)\n- Decision authority and dates: Signed by Eugene Paul Holzapfel, Delegate of the Civil Aviation Safety Authority, 2 May 2000; notified in the Commonwealth Gazette on 17 May 2000. (signature line; notification line)\n\nThis summary sticks to what the instrument itself says: it cancels the previous mandatory checks, and it records the FAA's determination as the stated reason. The AD does not include new technical guidance or quantified cost/benefit figures; it records a cancellation based on the FAA action. "},"kimi_summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is a revocation instrument that narrows regulatory scope by removing a requirement. It does not represent scope creep; rather, it reduces the scope of AD/RAD/68 by eliminating Amendment 2. The original intent of airworthiness directives is to mandate safety actions, and this document serves that purpose by removing an obsolete requirement."},"complexity_factors":["Extremely short document (approximately 200 words)","No defined terms section","No cross-references to other legislation beyond citing the parent regulation (Civil Aviation Regulations 1998)","Simple unconditional directive: single action (revocation) with clear effective mechanism","No exceptions, conditions, or procedural requirements","Essentially a notification of cancellation rather than an operative regulatory instrument imposing new obligations"],"plain_english_summary":"This document is an **Airworthiness Directive (AD)** — essentially a safety order issued by the Civil Aviation Safety Authority (CASA) that tells aircraft owners and operators what maintenance or inspections they must perform to keep their planes airworthy.\n\n**What this specific directive does:**\n- **Cancels (revokes) a previous safety requirement.** Specifically, it cancels Amendment 2 to Airworthiness Directive AD/RAD/68, which had required regular \"Mode C Transponder Altitude Checks.\"\n- A Mode C transponder is the equipment in an aircraft that automatically reports the plane's altitude to air traffic control radar. The cancelled directive had required repetitive testing of this equipment.\n\n**Why it matters:**\n- **Reduces unnecessary maintenance burden:** The FAA (American aviation regulator) determined these repetitive tests were unnecessary and actually caused wear on components. CASA is following this lead by cancelling the Australian equivalent requirement.\n- **Affects aircraft operators** who previously had to perform these altitude checks on their transponders — they no longer need to do so.\n- **Harmonisation with international standards:** Shows Australia aligning its safety regulations with the United States when evidence shows a requirement is redundant.\n\n**Key takeaway:** This is a deregulatory action — removing a maintenance requirement because it was found to be unnecessary and potentially counterproductive."}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks","history":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks/history","analysis":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks/analysis","conflicts":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks/conflicts","importantCases":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks/important-cases","documents":"/api/acts/ad-rad-68-amdt-2-mode-c-transponder-altitude-checks/documents"}}