AD/B747/320 - AFM Limitation - RVSM Operations

Reduced Vertical Separation Minimum (RVSM) airspace is a volume of airspace, typically between FL290 and FL410, where the vertical separation between aircraft is reduced from the standard 2,000 feet to 1,000 feet. This increases airspace capacity but places stricter demands on altitude-keeping systems. The directive targets this environment specifically because the closer proximity of aircraft increases the risk of wake turbulence encounters sufficient to trigger autopilot disconnects, as reported by the FAA.

Autopilot/flight director command mode refers to a mode where the autopilot or flight director actively controls the aircraft's flight path in response to commands from a system, rather than simply providing raw guidance or remaining in a basic hold mode. The prohibition applies only when the speed mode switch has the Performance Management System (PMS) selected. The PMS is a computerised system that computes optimal speeds for cruise, climb, and descent based on the flight plan and performance data. The directive leaves open the use of PMS generated airspeeds when the crew manually enters them via the Mode Selector Panel. The distinction matters: the prohibited configuration is when the PMS directly controls the speed mode, meaning the autopilot may be responding to speed commands from the PMS without crew intervention. The directive’s background cites unexpected autopilot disconnects induced by the passing of another aeroplane within 1,000 feet below. The mechanism is likely that wake turbulence causes rapid changes in airspeed or attitude, and when the autopilot is in PMS command mode, it may react in a way that leads to disconnect or altitude deviation. The FAA reports this as an observed failure mode.

Aircraft Flight Manual (AFM) Limitation is a legally binding part of the aircraft's certification documents. Revising the Limitations section means the prohibition becomes a mandatory operating condition. Any flight in RVSM airspace with the prohibited configuration engaged would be a breach of the AFM, which is itself a regulatory breach. The directive allows the operator to insert a copy of the directive itself into the AFM as a temporary means to satisfy the requirement, but once the AFM is generally revised (e.g., at the next revision cycle), the copy may be removed. This is a common mechanism to expedite compliance without waiting for a full manual reprint.

The directive references an FAA AD (2004-25-06 Amdt 39-13894). This is a bilateral recognition: CASA adopted the FAA's finding that an unsafe condition exists and requires corrective action. The FAA AD presumably has a similar effect in the United States. The directive does not restate the full text of the FAA AD, only notes its existence.

Exclusion for certain service bulletins means that operators who already complied with Boeing SB 747-34-2294 or 747-34-2296 do not need to take any action. These bulletins likely modified the autopilot/PMS interface or the AFM already. The existence of these bulletins suggests that Boeing had previously identified a similar risk and provided a design fix.

The directive directly affects operators of Boeing 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SP and 747SR series aeroplanes with variable numbers listed in Table 1. This includes a specific set of roughly 100 distinct variable numbers (e.g., RA521-RA528, RB071-RB075, RS251-RS259, among others). The variable number is a Boeing internal identifier tied to a production block or customer configuration. The effect extends to Australian registered aircraft falling within these variable numbers; aircraft not in Australia but operated by an Australian operator may also be subject if the regulations apply extra-territorially. The directive does not provide a complete list of tail numbers, so an operator must cross reference their aircraft's variable number. The variable number can typically be found on the data plate or in the aircraft maintenance records.

Aeroplanes on which either Boeing Service Bulletin 747-34-2294 (dated 25 May 1989) or 747-34-2296 (dated 1 July 1989) have been accomplished are excluded. This means operators who have already incorporated those service bulletins are not required to revise their AFM. However, they must still ensure that the AFM reflects the current configuration; if the SB work was not marked in the manual, the exclusion may be missed during an audit.

The directive imposes duties primarily on the operator or owner of the aircraft, as they are responsible for maintaining the AFM and ensuring compliance with Airworthiness Directives. However, the actual work of revising the AFM may be delegated to a maintenance organisation or a flight operations department. The requirement to insert a copy of the directive or a revised page is a manual task that could be performed by any authorised person. The crew (pilots) are ultimately the end users who must follow the AFM limitation; they need to be trained on the new prohibition. The directive does not address training explicitly, but compliance logically requires crew awareness.

The directive affects maintenance planners who must schedule the AFM revision within 10 days. Quality assurance departments must verify compliance and keep records. Flight operations personnel must update manuals and procedures. CASA inspectors will check compliance during surveillance activities. The cost burden falls on the operator: printing, distributing, and recording the AFM change, plus any crew briefing. Larger airlines with many affected aircraft may face a non-negligible administrative cost, but it is relatively low compared to a hardware modification.

The directive does not directly affect aircraft manufacturers, suppliers, or passengers, except possibly through reduced operational flexibility in RVSM airspace.

The primary duty is to revise the Limitations section of the AFM to include a specific prohibition statement. The operator must accomplish this within 10 days after the effective date (17 February 2005). The directive provides a permissible method: the operator may insert a copy of the directive itself into the AFM as a temporary revision. This is a straightforward administrative task that requires no engineering or modification. Once the AFM is subsequently revised through general revisions that include a statement identical to that required, the copy of the directive may be removed. This gives operators flexibility; they are not forced to wait for a full manual update.

The operator has the right to rely on the exclusion provided by prior accomplishment of Boeing SB 747-34-2294 or 747-34-2296. If the aircraft's records show those service bulletins were done, no further action is required. However, the records must be verifiable; the directive does not establish a grace period or alternative means of compliance. If an operator believes the risk is mitigated by other design features not covered by the specified service bulletins, there is no avenue for approval of an alternative in the text of the directive. The operator would need to seek a separate CASA approval under Part 39 of the CASRs, which is not mentioned in this source.

The directive does not include any obligations related to reporting changes, sending proof to CASA, or notifying the crew in any specific form. The duty is simply to have the AFM revised before flight in RVSM airspace. However, if the operator intends to operate in RVSM airspace, compliance is mandatory before such operation. If the aircraft never enters RVSM airspace, does the directive still apply? The directive states: "Revise the Limitations section ... to include the following statement." It does not condition the requirement on actual RVSM operations; the AFM must be revised regardless. But if the aircraft does not have RVSM approval, the limitation may be academic. However, the directive does not exempt aircraft not approved for RVSM. A strict reading suggests the AFM must contain the prohibition for all affected aircraft, even if they do not fly in RVSM airspace. This is a gotcha for operators that may think the directive is self-limiting.

The operator also has the right to remove the copy of the directive from the AFM once the general revisions contain an identical statement. But "identical" means the precise wording. Operators must check that the revision incorporates the exact text. If the revision uses different phrasing, the directive remains effective. The onus is on the operator to ensure the AFM limitation is present.

The directive does not specify record-keeping requirements. However, under CASR Part 39, compliance with Airworthiness Directives must be recorded in the aircraft maintenance log or equivalent. The source does not mention it, but it is a general obligation.

The directive itself does not explicitly state any penalty for non-compliance. As a legislative instrument issued under the Civil Aviation Act 1988 (by way of delegation from CASA), failure to comply with an Airworthiness Directive is an offence under the Civil Aviation Regulations 1988 or Civil Aviation Safety Regulations 1998. At the time of issue (2005), the relevant penalty provisions in CAR 1988 applied. Specifically, CAR 39 (now replaced by CASR Part 39) made it an offence to operate an aircraft that does not comply with an applicable AD. Penalties could include fines (penalty units) and potentially imprisonment for serious offences under section 20A of the Civil Aviation Act (reckless operation). However, those penalties are not grounded in the source text; we can only note what the source says. The source says nothing about penalties or enforcement. So we must state that.

The enforcement authority is CASA. CASA inspectors can ground an aircraft if they find that the AFM has not been revised in accordance with the directive. The aircraft would be considered unairworthy, and a flight without the AFM limitation could be in breach of the conditions of the airworthiness certificate. In practice, non-compliance might be discovered during routine airworthiness audits, ramp checks, or accident investigations. The 10-day compliance window is tight; operators who miss it by even a day could be non-compliant. However, enforcement discretion may apply; CASA may issue a direction to comply rather than immediate prosecution.

The directive is based on a finding of an unsafe condition. The background describes a scenario that could lead to a mid-air collision or loss of control. If an operator knowingly operated in RVSM airspace without the AFM limitation and an incident occurred, the operator could face civil liability and regulatory action beyond the AD violation. But that is speculative.

The source does not mention any alternative dispute resolution or appeal mechanism. Operators who dispute the need for the directive must seek a review of the AD through CASA's internal processes or through the Administrative Appeals Tribunal, but that is extra-textual.

This Airworthiness Directive is a specific regulatory instrument within the framework of the Civil Aviation Act 1988 and associated regulations. It interacts with the general provisions for airworthiness that require an aircraft to comply with all applicable ADs in order to be considered airworthy. The directive itself references FAA AD 2004-25-06 Amdt 39-13894, indicating that it is a bilateral adoption of a foreign AD. This is standard practice under the Bilateral Aviation Safety Agreement between Australia and the United States. The existence of the FAA AD means that the same prohibition applies to US-registered aircraft of the same type. Australian operators may have already complied with the FAA AD if they operate aircraft that were previously under US registration.

The directive also interacts with earlier service bulletins. Aeroplanes that have accomplished SB 747-34-2294 or SB 747-34-2296 are excluded. Those service bulletins are themselves voluntary but become mandatory when referenced in an AD. This shows how the AD system can adopt manufacturer recommendations as law.

The directive does not mention any interaction with other states' ADs, but it is possible that the same issue is addressed by other civil aviation authorities (e.g., EASA may have its own AD). An operator that operates in multiple jurisdictions must comply with each jurisdiction's requirements; however, the prohibition is the same, so no conflict arises.

The directive is a stand-alone requirement but it ties into the broader RVSM approval process. To obtain RVSM approval, an operator must demonstrate that its aircraft and procedures meet minimum altitude-keeping performance. This AFM limitation is part of that demonstration. The directive may also interact with Part 91 (general operating rules) and Part 121 (air transport operations) of the CASRs, as those parts require compliance with the AFM.

The directive does not affect any state or territory laws. It is a federal regulation under the Commonwealth's power over air navigation.

The source is the original issue of AD/B747/320 dated 6 January 2005, effective 17 February 2005. It carries the serial number 2/2005 (likely the second AD for Boeing 747 issues in 2005). There is no amendment history provided in this document. It does not reference any prior versions or superseded directives. This is the initial publication of this particular requirement for these 747 models. Since the source is a single page extracted from CASA's records, there is no indication that this AD has been amended, superseded, or withdrawn. However, given the age of the directive (over 19 years as of 2024), it is likely that it has been either superseded by a later AD (perhaps incorporating broader requirements or design changes) or cancelled because the affected aircraft have been retired from service. The source itself gives no such information. For an analyst, this means that this deep dive is based solely on the text as published in January 2005. Any further amendments or supersessions are outside the source. If this directive is still active, it remains in effect. If it has been superseded, operators must follow the later directive. The lack of amendment history in the source means we cannot state anything certain about post-2005 changes.

The source makes no mention of any litigation related to AD/B747/320. There are no court cases referenced in the text. Given the straightforward administrative nature of the directive (a simple AFM revision), it is unlikely that it was ever challenged in court. There may have been disputes about the underlying FAA AD or about the findings of the unsafe condition, but those would be in the United States, not Australia. No Australian court cases citing this specific AD appear in the source. As a matter of legal research, a high court challenge to an AD is rare; operators typically comply and seek alternative means if they disagree. The directive's justification is based on FAA reports of autopilot disconnects; if an operator had evidence that the prohibition was unnecessary, they could petition CASA for exemption or argue the AD is ultra vires, but no such cases are documented here. Therefore, the litigation history for this instrument is essentially non-existent. This section necessarily relies on the absence of information rather than positive evidence. The directive appears to have been implemented without controversy, at least as far as the source indicates.

Several aspects of this Airworthiness Directive could lead an operator to inadvertently be non-compliant.

First, the 10-day compliance period runs from the effective date, not from the date of receipt of the directive. If an operator receives the directive after 17 February 2005 (e.g., by mail from CASA), the clock has already started. Operators must have systems in place to monitor CASA AD publications and act immediately.

Second, the exclusion for service bulletins 747-34-2294 and 747-34-2296 might be overlooked. An operator who has accomplished those bulletins but fails to document them in the aircraft records might still perform the AFM revision unnecessarily; more critically, an operator who mistakenly believes an earlier modification addresses the issue but is not one of those two specific bulletins is not exempt. Only the exact bulletin numbers qualify. The directive does not accept equivalent modifications or later revisions of those bulletins unless explicitly stated.

Third, the prohibition applies only to the autopilot/flight director "in command mode with Performance Management System (PMS) selected on the speed mode switch". It does not prohibit other uses of PMS or autopilot. However, the AFM revision must include the exact statement as written. If the operator uses a paraphrased version, it may not satisfy the requirement. The directive says "when a statement identical to that above has been included in the general revisions of the AFM, the general revisions may be inserted into the AFM and the copy of this Directive may be removed." This implies that the statement must be word-for-word. Operators who issue a general revision with slightly different wording may still be required to retain the copy of the directive.

Fourth, the directive does not mention any procedure for returning to service after non-compliance. If an aircraft is found to have flown without the AFM limitation in RVSM airspace, it may be considered to have an unairworthy condition. The operator would need to ground the aircraft, revise the AFM, and possibly notify CASA. The directive does not provide a grace period for missed compliance.

Fifth, the directive applies to all aircraft with the listed variable numbers regardless of whether they are approved for RVSM operations. An operator with an aircraft that is not RVSM approved may think the directive is irrelevant. However, the directive requires the AFM revision as a standalone action; the aircraft's AFM must contain the prohibition even if it never operates in RVSM airspace. This could be an unnecessary compliance burden for non-RVSM operators, but it is nonetheless mandatory.

Sixth, the directive references FAA AD 2004-25-06, but the AD itself is Australian. If an operator holds a US registration or operates in US airspace, they must comply with both ADs. The FAA AD may have additional requirements not listed here (e.g., compliance times, alternative methods of compliance). The source does not reproduce the FAA AD, so operators cannot assume that compliance with the CASA AD is sufficient under FAA regulations.

Finally, the directive is effective from 17 February 2005. It does not have an expiry date. Unless superseded or cancelled, it remains in effect. An operator acquiring a used 747 from another operator must verify that this AD was complied with on the effective date and that the AFM still contains the prohibition. If the AFM has been revised since and the directive copy removed, the operator must ensure that the general revision contains the identical statement.

Compliance with AD/B747/320 is administrative and can be completed without modification to the aircraft hardware or software. The steps are as follows.

1. Determine applicability. Check whether the aircraft is one of the Boeing 747 models listed (747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747SP, 747SR) and obtain the Boeing variable number from the aircraft data plate or records. Compare that variable number against Table 1 of the directive. If the number falls within the inclusive ranges or is one of the single numbers listed, the aircraft is subject to the directive. If the variable number is not within the table, no further action is required. Also, check if the aircraft has accomplished Boeing Service Bulletin 747-34-2294 (dated 25 May 1989) or 747-34-2296 (dated 1 July 1989). If either has been accomplished (as recorded in the aircraft maintenance log or airworthiness records), the aircraft is excluded from the requirements. Document the basis for exclusion.

2. If the aircraft is subject and not excluded, obtain a copy of this Airworthiness Directive (AD/B747/320). The directive itself may be inserted into the AFM as a temporary revision. To comply, insert the copy into the Limitations section of the AFM. Ensure that the copy is legible and includes all parts (the prohibition statement, the note referencing FAA AD, and the background). The directive states that this may be done. No special approval is needed.

3. Within 10 days after 17 February 2005 (i.e., by 27 February 2005), the AFM must be revised. This means the copy of the directive must be physically inserted by that date. If the operator uses a binder system, the pages can be added. If the AFM is electronic, the revision must be made in the system. For historical compliance (i.e., for an aircraft acquired later), the operator must ensure that the AFM was revised within the original compliance period and still contains the prohibition.

4. Provide notice to flight crews. While not explicitly required by the directive, the AFM limitation must be briefed to flight operations personnel so that they are aware of the prohibition. This may involve updating Standard Operating Procedures (SOPs) and training materials.

5. Record compliance in the aircraft's airworthiness records. Although the directive does not state a specific record-keeping requirement, under CASR Part 39, compliance with ADs must be recorded. Typically, the aircraft maintenance log or an AD compliance certificate should note that AD/B747/320 has been complied with, the method used (insertion of directive copy or general revision), and the date of compliance.

6. Monitor for future changes. If the AFM undergoes a general revision that includes a statement identical to that required by the directive, the inserted copy may be removed. The operator must verify that the general revision contains the exact wording: "Operation of the autopilot/flight director in command mode with Performance Management System (PMS) selected on the speed mode switch during cruise in Reduced Vertical Separation Minimum (RVSM) airspace is prohibited. Use of PMS generated airspeeds and autopilot modes (e.g., IAS/Mach) with manually crew-entered airspeeds (via Mode Selector Panel) are allowed." If the wording matches, the copy can be removed and the general revision can be used instead. If it does not match, the copy must remain.

7. For aircraft not in RVSM airspace, compliance is still required. The AFM must contain the limitation even if the aircraft never enters RVSM. The operator cannot skip the revision on that basis.

8. If the aircraft is disposed of or sold, the airworthiness records should reflect compliance at the time of sale to assist the new operator.