{"id":"F2006B06537","name":"AD/RAD/82 - Prevent GPS Navigation unit from Providing Erroneous Cross-Deviation","slug":"ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48210,"registerId":"commonwealth-F2006B06537-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/RAD/82 - Prevent GPS Navigation unit from Providing Erroneous Cross-Deviation","content":"![](image.001.png)\n\n![](image.001.png)  \nAIRWORTHINESS DIRECTIVE\n\nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 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.\n\n![](image.001.png)  \n\nRadio Communication and Navigation Equipment\n\nAD/RAD/82 Prevent GPS Navigation unit from Providing\n\nErroneous Cross-Deviation\n\n  \n9/2004\n\nApplicability: Garmin AT, formerly UPS Aviation Technologies, Apollo GX50/55/60/65 TSO- C129a global positioning system (GPS) navigation units as listed below with software versions 3.0 through 3.4 inclusive:\n\n| Model | Part Number  | Description                    | Modification Level                                                     |\n| ----- | ------------ | ------------------------------ | ---------------------------------------------------------------------- |\n| GX50  | 430-6050-400 | Approach Certified GPS         | With any of the following mods:(H), (N), (P), (T) or (U);prior to (V)  |\n|       | 430-6050-401 | Approach Certified GPS         | Prior to (V)                                                           |\n|       | 430-5060-402 | Approach Certified GPS         | Prior to (V)                                                           |\n| GX55  | 430-6050-200 | Enroute/Terminal Certified GPS | With any of the following mods:(E), (J), (K), (M) or (N);prior to (R): |\n|       | 430-6050-201 | Enroute/Terminal Certified GPS | With any of the following mods:(E), (J), (K), (M) or (N);prior to (R)  |\n|       | 430-6050-202 | Enroute/Terminal Certified GPS | Prior to (R)                                                           |\n|       | 430-6050-203 | Enroute/Terminal Certified GPS | Prior to (R)                                                           |\n\n| GX60 | 430-6050-600 | Approach CertifiedGPS/COM          | With any of the followingmods:                                           |\n| ---- | ------------ | ---------------------------------- | ------------------------------------------------------------------------ |\n|      |              |                                    | (H), (N), (S), (AB) or(AC);prior to (AE)                                 |\n|      | 430-6050-601 | Approach Certified GPS/COM         | With any of the following mods:(H), (N), (S), (AB) or (AC);prior to (AE) |\n|      | 430-6050-602 | Approach Certified GPS/COM         | Prior to (AE)                                                            |\n|      | 430-6050-603 | Approach Certified GPS/COM         | Prior to (AE)                                                            |\n|      | 430-6050-604 | Approach Certified GPS/COM         | Prior to (AE)                                                            |\n| GX65 | 430-6050-800 | Enroute/Terminal Certified GPS/COM | With any of the following mods:(F), (L), (P), (Y) or (AA);prior to (AC)  |\n|      | 430-6050-801 | Enroute/Terminal Certified GPS/COM | With any of the following mods:(F), (L), (P), (Y) or (AA);prior to (AC): |\n|      | 430-6050-802 | Enroute/Terminal Certified GPS/COM | Prior to (AC)                                                            |\n|      | 430-6050-803 | Enroute/Terminal Certified GPS/COM | Prior to (AC)                                                            |\n|      | 430-6050-804 | Enroute/Terminal Certified GPS/COM | Prior to (AC)                                                            |\n\nNote 1: The above table was sourced from UPS Aviation Technologies Service Bulletin 561-4002-001, dated 19 April 2002, which was referenced in FAA AD 2004- 13-20 and the certification in the table refers to the FAA TSO C-129a class of the unit.\n\nRequirement: 1. Modify and test the software for the Apollo GX50/55/60/65 TSO-C129a GPS navigation unit by accomplishing all of the actions specified in paragraphs 3.B. and 3.C. of Service Bulletin (SB) 561-4002-001, dated 19 April 2002.\n\n2. Reidentify the modified Apollo GX50/55/60/65 TSO-C129a GPS navigation unit, according to paragraph 3.D. of SB 561-4002-001.\n\nNote 2: FAA AD 2004-13-20 Amdt 39-13702 refers.\n\nCompliance: For Requirement 1 \\- Within six months after the effective date of this Directive.\n\nFor Requirement 2 \\- Immediately following completion of Requirement 1\\. This Airworthiness Directive becomes effective on 2 September 2004.\n\nBackground: The United States Federal Aviation Administration (FAA) has advised that, under certain conditions, Garmin AT, Apollo GX series GPS navigation units with software versions 3.0 to 3.4 may provide erroneous cross-deviation information, which could result in the aircraft deviating from its intended course for a brief period of time. This erroneous information may place an excessive workload on the flightcrew while they monitor other available navigation data to avoid deviating off course.\n\nTo prevent the GPS unit from providing erroneous information, this Directive requires modification and testing of the software for the GPS navigation units.\n\n![Signature of Bernard Malcolm Hole Delegate of the Civil Aviation Safety Authority](image.002.png)  \n\nBernard Malcolm Hole\n\nDelegate of the Civil Aviation Safety Authority 20 July 2004\n\n![](image.001.png)  \n\nThe above AD is notified in the Commonwealth of Australia Gazette on 11 August 2004.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific software defect in specific GPS units. The scope remains precisely limited to the identified unsafe condition and affected products, with no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Extensive tabular data with 15+ specific part numbers and modification levels requiring careful matching","Cross-reference to external FAA Airworthiness Directive (2004-13-20) and manufacturer Service Bulletin (561-4002-001)","Software version conditionality (versions 3.0 through 3.4 inclusive)","Dual compliance deadlines with dependency (Requirement 2 triggers immediately after Requirement 1)","Technical aviation terminology requiring domain knowledge (TSO-C129a, cross-deviation, modification levels)"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of certain Garmin/Apollo GPS units (GX50/55/60/65 with specific software 3.0–3.4) to install a manufacturer software update and relabel the unit. The fix corrects a bug that can briefly display incorrect cross‑deviation, risking undetected course drift.\n\nIf your unit matches the listed parts/levels, you must update and test the software within six months and apply the new label."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"This AD implements a narrowly focused corrective action to address a specific unsafe condition reported by the FAA for particular Apollo GX series GPS units and software versions. It does not broaden the subject matter beyond that original safety purpose: it prescribes the manufacturer’s software modification, testing and reidentification for the listed units. There is no indication in the text that the AD expanded its scope beyond the FAA’s identified problem or beyond the affected units/software versions."},"complexity_factors":["Short, single-purpose AD with two substantive requirements (modify/test; reidentify).","Applicability determined by a table of specific models, part numbers and modification levels (increases identification complexity).","Cross-reference to an external technical document: Service Bulletin 561-4002-001 (paragraphs 3.B, 3.C, 3.D) for the detailed technical steps.","Reference to FAA AD 2004-13-20 (informational cross-reference only).","Single compliance deadline (six months) and an immediate follow-on action (reidentification).","No nested exceptions or multiple conditional compliance tracks in the AD itself."],"plain_english_summary":"**What this directive does (mechanically)\n\n- This Airworthiness Directive (AD) requires owners/operators of specific Garmin AT (formerly UPS Aviation Technologies) Apollo GX50, GX55, GX60 and GX65 TSO‑C129a GPS navigation units with software versions 3.0 through 3.4 to have the unit software modified, tested and reidentified.\n- The required work is to be done exactly as set out in Service Bulletin (SB) 561-4002-001 (paragraphs 3.B, 3.C and 3.D): apply the software modification, run the prescribed tests, and update the unit identification.  \n- The software modification and testing must be completed within six months of the AD’s effective date; reidentification is to be done immediately after the modification and testing are finished.\n- The AD is issued under the Civil Aviation Safety Regulations (CASR) power to require corrective action for an unsafe condition; compliance is mandatory for affected aircraft/equipment.\n\n**Who this affects**\n\n- Aircraft owners and operators that have any of the listed Apollo GX50/55/60/65 GPS units installed and that have the software at versions 3.0, 3.1, 3.2, 3.3 or 3.4. The AD lists specific part numbers and modification levels to identify affected units.\n- Maintenance organisations or technicians who will perform the software modification, testing and reidentification, and the organisations that keep maintenance records for the aircraft.\n\n**Why the action is required (stated rationale)**\n\n- The FAA reported that, under certain conditions, the listed GPS units (software versions 3.0–3.4) may provide erroneous cross‑deviation information. That incorrect information could briefly lead an aircraft off its intended course and increase pilot workload while they check other navigation sources. The AD’s stated purpose is to prevent the GPS from providing that erroneous cross‑deviation information by installing and verifying corrected software.\n\n**Practical consequences, costs and incentives**\n\n- Who pays: aircraft owners/operators pay for the software modification, associated testing, any necessary removal/installation labour, and downtime while the unit is out of service. Maintenance record entries and reidentification work are also an operator cost.\n- Who decides: the CASA delegate issued the AD under CASR subregulation 39.1(1); operators must comply by the stated deadlines unless they obtain an approved alternative method of compliance from CASA.\n- Behaviour change required: operators must inspect rosters to identify affected units (by part number, mod level and software version), schedule the modification and test, and update the unit identification and maintenance records.\n- Implementation risks and compliance burden: locating all affected units in a fleet can be time-consuming because the AD requires matching part numbers and modification levels; units may need to be sent to authorised service centres or specific repair facilities (depending on how the SB is implemented), creating potential scheduling bottlenecks and short-term capacity constraints.\n- Effects on market participants: authorised service centres and the manufacturer are likely to gain the bulk of modification work (concentrated benefit). Independent maintenance providers may be able to perform the work if they have the SB instructions and necessary tooling, but the AD and SB together tend to centralise demand for documented, traceable modification work and record‑keeping. The directive does not itself set prices or approve service providers; market pricing for the retrofit will depend on supply of qualified technicians and facilities.\n\n**Trade-offs, opportunity costs and substitutions**\n\n- The AD trades short-term operator costs (modification, testing and downtime) against reduced risk of incorrect navigation guidance. Operators can substitute by relying on other certified navigation sources while arranging the retrofit, but regulatory compliance still requires the modification within the specified period.\n\n**Limitations of the directive and sources of uncertainty**\n\n- The AD relies on a manufacturer service bulletin (SB 561-4002-001) for the technical steps; the AD does not itself prescribe alternative technical methods except through the SB or an approved alternative method of compliance. The extent to which independent repair stations can perform the work depends on the SB’s instructions and any applicable approvals, which the AD does not specify.\n\n**Legal effect in one line**\n\n- The AD makes the software modification, testing and reidentification mandatory for the listed units within the timeframe stated; failure to comply with an AD is a breach of the CASR requirements for continuing airworthiness.\n\n(References: applicability table in the AD for affected models/part numbers/mod levels and the Requirement and Compliance sections describing required actions and the six‑month deadline.)"},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation","history":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation/history","analysis":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation/analysis","conflicts":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation/conflicts","importantCases":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation/important-cases","documents":"/api/acts/ad-rad-82-prevent-gps-navigation-unit-from-providing-erroneous-cross-deviation/documents"}}