{"id":"F2006B08846","name":"AD/DC4/39 Amdt 1 - Aircraft Flight Manual, Flight into Icing Conditions","slug":"ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":52332,"registerId":"commonwealth-F2006B08846-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/DC4/39 and issues the following AD under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/DC4/39","sectionType":"part","heading":"AD/DC4/39","content":"# AD/DC4/39\n\n## Amdt 1\n\nApplicability: All models DC4. Requirement: Revise:\n\n  \n\n## Aircraft Flight Manual, Flight into Icing Conditions\n\n  \n7/2000","sortOrder":1},{"sectionNumber":"Amdt 1","sectionType":"part","heading":"Amdt 1","content":"## Amdt 1\n\nApplicability: All models DC4. Requirement: Revise:","sortOrder":2},{"sectionNumber":"Aircraft Flight Manual, Flight into Icin","sectionType":"part","heading":"Aircraft Flight Manual, Flight into Icing Conditions","content":"## Aircraft Flight Manual, Flight into Icing Conditions\n\n  \n7/2000","sortOrder":3},{"sectionNumber":"\"WARNING\"","sectionType":"part","heading":"\"WARNING\"","content":"# \"WARNING\"\n\nSevere icing may result from environmental conditions outside of those for which the aircraft is certificated.\n\nFlight in freezing rain, freezing drizzle, or mixed icing conditions (super cooled liquid water and ice crystals) may result in:\n\n    ice build-up on protected surfaces and exceed the capability of the ice protection system, or\n\n    ice forming aft of the protected surfaces.\n\nThis ice may not be shed using the ice protection systems, and may seriously degrade the performance and controllability of the aircraft.\n\nDuring flight, severe icing conditions that exceed those for which the aircraft is certificated shall be determined by the visual cues described below. If one or more of these visual cues exists, immediately request priority handling from Air Traffic Control to facilitate a route or an altitude change to exit the icing conditions. The cues are:\n\n    unusually extensive ice accumulation on the airframe and windscreen in areas not normally observed to collect ice, and/or\n\n    accumulation of ice on the upper surface of the wing aft of the protected area, and/or\n\n    accumulation of ice on the engine nacelles and propeller spinners farther aft than normally observed.","sortOrder":4},{"sectionNumber":"THE FOLLOWING WEATHER CONDITIONS MAY BE ","sectionType":"part","heading":"THE FOLLOWING WEATHER CONDITIONS MAY BE CONDUCIVE TO SEVERE IN-FLIGHT ICING:","content":"# THE FOLLOWING WEATHER CONDITIONS MAY BE CONDUCIVE TO SEVERE IN-FLIGHT ICING:\n\n    Visible rain at temperatures below 0 degrees Celsius ambient air temperature;\n    Droplets that splash or splatter on impact at temperatures below 0 degrees Celsius ambient air temperature.","sortOrder":5},{"sectionNumber":"PROCEDURES FOR EXITING A SEVERE ICING","sectionType":"part","heading":"PROCEDURES FOR EXITING A SEVERE ICING","content":"# PROCEDURES FOR EXITING A SEVERE ICING\n\nENVIRONMENT: (These procedures are applicable to all flight phases from take-off to landing.)\n\nMonitor the ambient air temperature.\n\nWhile severe icing may form at temperatures as cold as \\-18 degrees Celsius, increased vigilance is warranted at temperatures around freezing when visible moisture is present.","sortOrder":6}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is an amendment (Amdt 1) to an existing Airworthiness Directive. It replaces the previous version but maintains the same core purpose: ensuring DC-4 flight manuals contain adequate icing warnings. The scope remains tightly focused on flight manual revisions for this specific aircraft type's icing procedures."},"complexity_factors":["Very short document — approximately 400 words","Only 1 defined term implicitly referenced (Aircraft Flight Manual)","No cross-references to other legislation beyond the enabling regulation (CAR 1998 subregulation 39.1(1))","Simple structure: applicability, requirement, compliance timing (7/2000), and the actual manual text","No nested exceptions or conditional logic — straightforward mandatory action","Single aircraft type affected (DC-4), single action required (manual revision)"],"plain_english_summary":"This AD revokes and replaces the previous safety notice for Douglas DC-4s and requires operators to revise the Aircraft Flight Manual to add explicit warnings and procedures about severe icing, including conditions like freezing rain and freezing drizzle.\n\nIt affects DC-4 pilots/operators by mandating clear visual-ice recognition and immediate priority escape actions to avoid ice beyond de‑icing reach — a critical update to reduce the real crash risk posed by severe icing on this vintage fleet."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":false,"description":"The amendment revokes the prior AD and issues revised Flight Manual text for the same applicability ('All models DC4'). It updates required manual content and crew procedures but does not expand the set of affected aircraft beyond all DC‑4 models."},"complexity_factors":["Technical subject matter: requires knowledge of meteorology and aeroplane ice‑protection limits.","Operational judgement: determination of 'severe' icing depends on pilot visual cues rather than objective instrumentation.","Non‑prescriptive procedures: exit actions rely on crew discretion and ATC cooperation, not a fixed checklist.","Fleet administrative burden: requires revising flight manuals and associated crew training for all DC‑4 operators.","Coordination dependency: effectiveness depends on timely ATC priority handling and ability to change route/altitude.","Ambiguous thresholds: temperature and moisture descriptions (e.g. freezing rain, mixed icing) leave room for interpretation."],"plain_english_summary":"This amendment requires all DC‑4 operators to update the Aircraft Flight Manual to add a warning and procedures about severe in‑flight icing. It tells flight crews how to recognise severe icing visually, to monitor ambient air temperature, and to seek priority ATC handling to change route or altitude to exit such conditions. It affects DC‑4 pilots, operators and operators’ documentation/training budgets because it imposes a fleet‑wide manual change and operational actions based on crew judgement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions","history":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions/history","analysis":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions/analysis","conflicts":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions/conflicts","importantCases":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions/important-cases","documents":"/api/acts/ad-dc4-39-amdt-1-aircraft-flight-manual-flight-into-icing-conditions/documents"}}