AI2379 AND AI171: INVESTIGATIVE INDEPENDENCE CANNOT BECOME INSTITUTIONAL SILENCE

 A preliminary accident report is not expected to determine causation, provide an exhaustive analysis, or pronounce definitive conclusions. But that limitation cannot serve as a convenient justification for withholding pertinent facts already established. Investigative independence and transparency are not competing principles. A credible investigation requires both.

The Aircraft Accident Investigation Bureau (AAIB) therefore needs to confront a fundamental question: why does important factual information repeatedly surface in the public domain through unnamed “civil aviation sources”, leaked documents and media reports before the investigating authority acknowledges it?

For a major aviation occurrence, periodic factual briefings should be integral to the investigative process. They need not speculate on causation. They need only inform the public of what has been established, what remains under examination, what evidence is being analysed, and whether any immediate safety concern has been identified.

Silence does not suppress speculation. It creates the conditions for speculation to flourish.

AI2379: A Narrative That Changed Outside AAIB

The handling of AI2379 illustrates the problem.

The initial public narrative was turbulence. As late as 6 August, Civil Aviation Minister K. Rammohan Naidu was still discussing the occurrence principally in those terms. No official public reference mentioned the extraordinary transient loss of hydraulic pressure later identified in all three hydraulic systems.

Yet a substantially different story was already emerging elsewhere.

The Aviation Herald published a more technically detailed account on 5 August. Media organisations subsequently reported hydraulic-system problems, in some cases attributing their information to civil-aviation or investigative sources. By 10 August, reports were openly referring to a transient triple-hydraulic-system failure. A copy of the aircraft's post-flight technical report, apparently downloaded on 4 August and showing the relevant failure messages, surfaced publicly on 13 August.

Eventually, Airbus DFDR analysis and the AAIB preliminary report established the essential fact: the aircraft had experienced an extraordinary, rapid sequence of events involving loss of hydraulic pressure across all three systems, accompanied by significant degradation of flight-control capability.

The early reporting was therefore not simply wild media speculation. Its central technical assertion was subsequently substantially validated.

That raises an uncomfortable question. If such information was sufficiently credible to circulate among aviation sources and journalists, why was the investigating authority not the authoritative source explaining what was known and, equally importantly, what was not known?

The Captain's Condition: An Unanswered Human-Factors Question

Another issue requires clarification.

Media reports citing unnamed sources claimed that one pilot fell in the cockpit and required assistance from the cabin crew. Subsequent accounts went further, alleging that the PIC appeared unsteady after landing, required assistance to sit, and was physically supported while providing the post-flight urine sample (India Today). These reports remain unverified allegations unless the AAIB confirms them. They should not be presented as established fact.

But they cannot simply be ignored.

The relevant investigative question is clear:

What was the PIC’s physical and functional condition immediately before, during and after the occurrence, and why was he reportedly assisted?

The preliminary report states that, after recovering from the upset, the captain assumed control of the aircraft. If reports that he had fallen, was unsteady, or required assistance are accurate, an obvious operational question follows: why was control transferred to him?

Conversely, if the captain was fully fit and functioning normally, the AAIB could dismiss this speculation with a factual statement.

Both versions cannot comfortably coexist without an explanation.

Why Continue for Another 98 Minutes?

The operational decision following the hydraulic event raises an even more pressing question.

The aircraft had just experienced an apparently unprecedented transient loss of hydraulic pressure affecting all three systems, together with temporary degradation of key flight-control functions. The systems recovered, but the initiating mechanism remained unknown.

The crew nevertheless continued to their destination for about another 98 minutes rather than diverting to the nearest suitable airport.

That decision warrants rigorous examination.

What ECAM warnings and system indications were available to the crew? What did they understand about the sequence of hydraulic losses and subsequent recovery? Were the systems indicating normal operation afterwards? Did the crew appreciate that three hydraulic systems had apparently been affected within seconds of one another? What technical, operational or dispatch considerations supported continuation?

The issue is not whether hindsight can produce a better decision. The issue is whether continuation was consistent with the information actually available to the crew at the time.

That is precisely the sort of factual context an investigating authority can explain without determining whether probable cause exists.

An Aircraft-Specific Failure—or a Fleet Safety Issue?

The technical implications are equally significant.

VT-EXO's maintenance history is available to investigators. Airbus participated in the technical examination. DFDR data were recovered. Components and hydraulic fluid samples were reportedly subjected to further examination.

Yet the central technical question remains publicly unresolved:

Was this an aircraft-specific anomaly, or was there any possibility of a failure mechanism relevant to the wider A320neo fleet?

The distinction is critical.

The fleet was not grounded. No fleet-wide Airworthiness Directive was issued. No publicly known urgent service bulletin was issued. No comparable warning to operators emerged. This may ultimately indicate that investigators and Airbus found no evidence requiring immediate fleet action.

But the absence of regulatory action is not, by itself, an explanation.

If the analysis demonstrated that continued operation of the fleet posed no immediate safety concern, stating this would strengthen public confidence rather than compromise the investigation.

More troublingly, technical material reportedly linked to Airbus's early analysis was published publicly and later withdrawn on confidentiality grounds. Whether that material was authentic, preliminary or incomplete is precisely why authoritative communication matters. When official information is absent, leaked technical material inevitably acquires an authority it may not deserve.

What Is Known—and What Is Not

AI2379 is not an investigation starved of evidence.

The DFDR and CVR were available. The flight and cabin crew could be interviewed. Maintenance records were available. The post-flight technical report was available. Airbus and BEA participated in the technical investigation. The sequence of aircraft behaviour could therefore be reconstructed with considerable precision.

The immediate aircraft response—the altitude excursion, flight-control degradation, hydraulic-pressure losses and subsequent recovery—is well known.

What remains publicly unresolved is the most important technical question: what initiated the extraordinary hydraulic event?

That uncertainty is entirely legitimate. Complex technical investigations take time.

What is harder to defend is withholding established factual information merely because the ultimate causal mechanism is unknown.

AI171 Shows the Same Institutional Problem

The concern is not limited to AI2379.

The Supreme Court proceedings on AI171 revealed a similar communication deficit. Despite notices issued in September 2025, the Court was informed in January 2026 that the Centre and AAIB had still not filed their responses, and the investigating side was reportedly unrepresented when the matter was taken up. At a further hearing scheduled for May, counsel for AAIB was reportedly absent.

AAIB subsequently filed its substantive response opposing a court-monitored investigation and appeared before the Court to defend its investigative process.

Whatever the petition's legal merits, the optics are damaging.

An accident-investigation authority handling one of India's most consequential aviation disasters should not have to be repeatedly pressed—by courts, families, professional organisations or the media—to explain its procedures.

Transparency Is Not Premature Causation

There is a tendency to frame demands for information as demands for premature conclusions, but that is a false choice.

Nobody should expect AAIB to announce a probable cause before the evidence supports it. Nobody should expect protected CVR material, sensitive personal information or speculative technical hypotheses to be released merely to satisfy public curiosity.

But verified factual information is different from investigative speculation.

AAIB can say what the recorders show without explaining why it happened. It can describe components under examination without predicting what those examinations will establish. It can state whether an immediate fleet-safety concern has been identified without prejudging final causation. It can clarify demonstrably false narratives without compromising investigative independence.

That is what mature accident-investigation authorities do.

The present approach risks producing precisely the opposite outcome. Official silence leaves journalists reliant on anonymous sources. Technical documents leak. Partial information is amplified. Competing narratives become entrenched. Investigators then cite confidentiality to avoid discussing information already in the public domain.

Confidentiality cannot replace communication.

AAIB's responsibility is not merely to produce a technically defensible final report months or years after an occurrence. It must also preserve confidence in the investigative process during the investigation.

AI2379 demonstrates why this matters. The public was initially told about turbulence. Hydraulic-system information emerged elsewhere. Technical documents surfaced, and Airbus analysis was reported. Questions arose about the captain's physical condition. The decision to continue for another 98 minutes remained unexplained. Eventually, the preliminary report confirmed much of the underlying technical sequence.

The problem is therefore no longer simply a matter of insufficient information.

It is a problem of who provides that information, when it is provided, and whether the investigating authority remains the most credible source of facts about its own investigation.

On that measure, AAIB has serious grounds for recovery.

Investigative independence deserves protection, but institutional silence does not.

Note: The Final report on AI171 is expected on 13 Oct 2026. Hope it puts some of the ongoing speculations to rest.

Author: GR Mohan

AI2379: Transparency Must Not Be Lost in the Investigation

 The preliminary report on Air India flight AI2379 raises more questions than it answers. That is not, by itself, a criticism of an accident investigation. Preliminary reports are not intended to establish causation or apportion blame. But when an aircraft loses all three hydraulic systems in rapid succession, loses autopilot and flight-control capability, triggers a stall warning, and undergoes a significant altitude excursion, the aviation community is entitled to expect a clear account of the established facts and any immediate safety implications.

AI2379, an Airbus A320-251N, was operating from Phuket to Delhi on 4 August 2026 with 145 people on board. The aircraft was cruising at FL360 when, according to the Aircraft Accident Investigation Bureau (AAIB), the flight-control system detected a loss of Green hydraulic pressure at 04:02:43 UTC. Four seconds later, Blue and Yellow hydraulic pressures were also reported as lost. At 04:02:48, the autopilot disconnected, and a continuous, repetitive chime sounded. Three seconds later, a stall warning was triggered.

The aircraft initially climbed 372 feet above its assigned level, then descended 292 feet. The First Officer, who was Pilot Flying, attempted to control the aircraft before the Pilot-in-Command took over. (Unofficial reports indicate that the pilot was standing behind the copilot, fell during the incident, and was helped into the seat by the cabin crew. After landing, the crew assisted him off the aircraft because he could not move on his own.) Remarkably, the Blue hydraulic system recovered almost immediately, followed within seconds by Yellow and Green, with the flight-control surfaces recovering and normal aircraft operation restored. The central technical question is therefore clear: why did three normally independent hydraulic systems apparently lose pressure almost simultaneously, and why did they recover within seconds?

The preliminary report does not answer that question. Nor should it be expected to at this stage. What is harder to understand is why the report offers so little indication of what the investigation team has established about this extraordinary sequence, despite already having access to the principal sources of evidence.

The AAIB states that it recovered, downloaded, and made both the CVR and DFDR available to the investigation team. The AAIB also conducted in-person interviews with the pilots and cabin crew. It further notes that Airbus technical experts, assigned through France’s BEA, inspected the aircraft between 13 and 15 August. Investigators then removed hydraulic components and collected fluid samples for further analysis, and collected maintenance and operational records, fuel and oil samples, and ATC data.

In other words, this is not an investigation awaiting evidence. Considerable evidence was already in hand, making the lack of a meaningful technical safety assessment particularly striking. Classifying it as an accident should not be a reason to withhold established safety-relevant facts. A legitimate distinction exists between releasing factual information and prematurely declaring a probable cause. The former can support safety; the latter can prejudice an investigation.

AAIB need not—and should not—speculate publicly about the root cause while evidence is still being analysed. But it could have stated clearly what is already known. That would neither compromise the investigation nor assign blame.

Another issue that cannot be overlooked concerns what happened after the hydraulic systems recovered.

The report records that the cabin supervisor informed the cockpit of the injuries. The aircraft experienced a triple hydraulic failure, a temporary loss and recovery of flight controls, and an altitude upset. Yet the crew elected to continue to Delhi for approximately 1 hour 28 minutes rather than divert. The preliminary report records that decision but does not analyse it. This decision warrants careful professional scrutiny.

The investigation must establish precisely what the crew saw on the ECAM, which hydraulic indications remained after recovery, and what the CVR and crew interviews reveal about the crew’s assessment and decision-making.

There have also been reports of speculation about “human intervention”. The published chronology, by itself, does not establish that humans deliberately initiated the hydraulic failures. Any conclusion about crew input must be based on the correlation of control inputs, system parameters, ECAM events, warnings, and CVR evidence—not on selective leaks or anonymous briefings.

The preliminary report does not establish that the toxicology result caused, contributed to, or was related to the hydraulic failure or altitude excursion. The technical sequence remains unexplained.

What Airbus knows matters

Perhaps the most uncomfortable aspect is the apparent discrepancy between what has emerged publicly from technical sources and what has appeared in the official preliminary report. The AAIB has already confirmed Airbus's technical involvement. Yet the preliminary report makes no technical safety recommendations to Airbus or the operator regarding the apparent simultaneous loss of all three hydraulic systems.

That is not necessarily evidence of an investigative failure. A safety recommendation should be based on a sufficiently validated safety issue. If the investigation has not yet established the mechanism, an immediate fleet-wide technical recommendation may not be justified.

But this raises an important question: has the investigation established that the event was confined to VT-EXO, or has it carried out an interim fleet-risk assessment?

If the answer is yes, the aviation community should be told why no precautionary action is considered necessary. If the answer is no, that too warrants explanation.

Ultimately, a safety investigation is about learning from the last event before the next—not merely explaining it.

Transparency is itself a safety tool

At present, there is insufficient evidence to accuse AAIB of a deliberate cover-up. Such an allegation would be premature and unfair. However, the current communication strategy creates an avoidable perception of selective disclosure.

When official silence is accompanied by fragmented technical information emerging through other channels, speculation inevitably fills the vacuum. That is particularly dangerous when the event involves a modern transport aircraft apparently losing all three hydraulic systems simultaneously. AAIB’s own report states that its sole objective is to prevent future accidents and incidents, not to apportion blame or liability. That principle should extend to its communication with the aviation community. Its only substantive public statement says it is collecting evidence and that no conclusions should be drawn from isolated information. Meanwhile, detailed engineering information has emerged through the media. The consequence is perverse: the official investigator supplies less factual information than leaked Airbus and maintenance documents, leaving unofficial sources to define the public narrative.

And that creates exactly the problem we discussed previously with AI 171: confidentiality is being interpreted as silence rather than as disciplined transparency.

AI2379 presents an extraordinary technical event, a significant crew decision, and a potentially important systemic safety issue. The final cause may take months to determine. Selective leaks to the media have clouded the investigation and shaped the public narrative. There is no justification for allowing uncertainty about the cause to become uncertainty about the facts.

The aviation community does not need premature conclusions.

It needs the truth about what is already known.

Author: GR Mohan

Accident Investigation in India: Silence Is Not Transparency

 Aircraft accident investigations take time, which is understandable.

What is harder to justify is prolonged silence when verified facts are already available.

The recent handling of Vietnam Airlines flight VN34 in Munich, the mid-air collision over the Potomac in the United States involving Air India flight AI2379, and the ongoing investigation into AI171 raise an important question for India: should an investigating authority remain largely silent until it is ready to discuss probable cause, or should it progressively share established facts as the investigation progresses?

These are not the same.

Investigators should not speculate. They should not announce causes before the evidence supports them. But investigative caution does not require an information vacuum.

Following the VN34 incident at Munich on 15 August 2026, Vietnamese aviation authorities released a factual account within about a day. It detailed the sequence of events, the warnings received, the crew’s decision to return, and how passengers were handled afterwards.

It did not attempt to explain why the incident happened. That is the key distinction.

A wide gap exists between saying nothing and declaring a cause. Within that gap lie verified facts: recorded warnings, aircraft behaviour, systems under examination, recorder recovery, completed tests, and safety actions already taken.

Sharing such information does not compromise an investigation. It helps establish the investigating authority as the most credible source of information. The January 2025 Potomac mid-air collision provides an even clearer example. The US National Transportation Safety Board held repeated briefings, progressively released factual information, and later held public hearings while its investigation continued. The final determination still took about a year.

The NTSB did not confuse transparency with premature judgement.

Instead, it allowed the public and the professional community to see that the investigation was progressing.

That visibility matters.

In contrast, India's handling of AI2379 left a significant information gap. AAIB confirmed it had opened an investigation and said it would release further information at an appropriate stage. Yet other sources later released important technical details on hydraulic-system behaviour and flight-control response. The Airbus technical analysis of the DFDR data, which was initially available, was later withdrawn from public view.

That is not an ideal situation.

If reliable technical information is already available to investigators, the official investigating authority should ideally be the first to inform the public of what has been established and what remains uncertain.

A statement that a system lost pressure, that specific warnings were recorded, or that flight controls became temporarily unavailable is not a causal conclusion. It is factual information. Determining why it happened is a separate analytical task.

The distinction between facts and causation should be fundamental to investigative communication.

AI171 raises the issue at an entirely different level.

The accident occurred on 12 June 2025. AAIB released a preliminary report one month later. A year after the accident, it stated that it had carried out an extensive examination of technical, operational, organisational and human factors.

That is reassuring as far as it goes.

But it also invites a reasonable question: what has that extensive examination established that it can now responsibly share?

The criticism is not that AAIB has failed to announce a cause. A catastrophic accident involving a modern wide-body aircraft may legitimately require a lengthy and complex investigation.

The more pressing concern is why so little additional factual information from the investigating authority has entered the public domain.

a) What systems have been examined?

b) Which component tests have been completed?

c) Have any hypotheses been eliminated?

d) Have any interim safety concerns emerged?

e) What major areas remain unresolved?

None of these questions requires the disclosure of protected cockpit voice recordings, confidential witness testimony, or evidence whose release could prejudice the investigation.

They simply ask where the investigation is.

An information vacuum does not stop speculation. It encourages it.

When the investigating authority offers limited information, others tend to fill the void with anonymous sources, leaks, media commentary, social media analysis, and complex technical theories. This pattern can have unintended consequences, undermining the purpose of investigative restraint. Rather than reducing confusion, institutional silence may actually allow it to grow.

Some may be informed, but many may not be.

The unfortunate result is that silence intended to prevent confusion can cause more confusion.

There is also a longer-term concern.

Public attention peaks immediately after an accident or serious incident and naturally declines over time. No evidence shows that AAIB deliberately delays to let public interest fade, and such a motive should not be alleged without proof.

However, prolonged non-communication can still produce that effect.

By the time substantive findings finally emerge, public scrutiny may have substantially diminished.

That is why periodic factual disclosure should not be regarded as a public-relations exercise. It should be recognised as part of modern safety-investigation practice.

ICAO Annex 13 properly protects certain investigative records and sensitive evidence. But confidentiality of protected material should not become opacity about the investigation's progress.

A professional investigation authority should be able to say:

a) These are the facts currently established.

b) These matters are still under examination.

c) These issues remain unresolved.

d) No conclusion on probable cause has yet been reached.

That is not premature disclosure. It is disciplined transparency.

The communication issue also raises a further concern: independence.

AAIB was established to separate accident investigation from DGCA’s regulatory function. That was both necessary and sensible. However, AAIB still operates administratively within the Ministry of Civil Aviation.

There is no evidence that MoCA or DGCA has improperly interfered with the AI171 or AI2379 investigations, and it would be irresponsible to suggest otherwise without proof.

But institutional independence is not only about whether interference has occurred. It is also about whether the structure is sufficiently independent to remove any reasonable perception of it.

An accident investigation may ultimately need to examine regulatory oversight, certification, air traffic management, airport operations, or government aviation policy. The investigating authority must therefore be positioned to scrutinise the entire aviation system, including regulators and government agencies, without ambiguity.

Independence must be both genuine and visible.

India does not need AAIB to become a running commentary service. Nor should investigators respond to every speculative theory in the media.

What is needed is simpler: a deliberate policy of periodic factual communication.

For major accidents and serious incidents, AAIB could issue concise updates at key milestones, covering recorder analysis, systems under examination, major tests completed, and any immediate safety action. Each update could make clear that the information is factual and provisional, and that no causal conclusion should be inferred.

VN34 and Potomac show that transparency and investigative rigour are not opposites.

AI2379 and AI171 suggest that India has yet to maintain that balance consistently.

The real question is not whether AAIB should pronounce causes earlier.

It is whether India’s accident-investigation system should communicate more openly while it works.

Investigations require patience.

Public confidence requires visibility.

The two are not incompatible.

 

Author: GR Mohan

VietJet VN34: A Tail Strike Or Something More Alarming?

 The Vietnam Airlines VN34 incident at Munich on 15 August 2026 was more than a tail strike. The Boeing 787-9 used almost the entire 4,000-metre Runway 26L before rotating very late, striking its tail and reportedly becoming airborne at or beyond the runway end. The key issue isn’t just the tail strike but why the aircraft couldn't accelerate normally and why the crew recognised the performance problem so late.

The crew was highly experienced, comprising three captains and one first officer, with a combined total of over 60,000 flying hours. This makes it a significant human-factors case. Experience alone doesn’t ensure effective monitoring, and having three captains may have created complex CRM dynamics, such as authority gradients or role confusion.

According to the crew, acceleration stalled around mid-runway, briefly resumed, then worsened again. By then, they believed there wasn’t enough runway left for a safe rejected take-off and decided to continue with maximum thrust.

This unusual acceleration pattern is critical. A simple error—such as incorrect weight, temperature, flap setting, or V-speeds—would usually cause consistently poor acceleration, not a pattern of loss, recovery, and then slowdown. This suggests possible intermittent retarding forces, such as unintended brake application, wheel resistance, or a brake-system fault.

Photographs and videos reportedly show brake or tyre marks near the runway end, but it’s unclear what they signify—whether they caused the acceleration loss or resulted from the aircraft departing the paved surface. Only flight recorder data can clarify the sequence.

The BFU recovered both the flight data and cockpit voice recorders. Analysing them should involve correlating engine thrust, acceleration, brake pressure, wheel speed, pilot inputs, flap settings, V-speeds, pitch, and control inputs over time.

If thrust was normal but acceleration dropped suddenly, the cause was likely due to external drag; if brake pressure increased at the same time, it suggests either crew input or a brake malfunction.

Until the data is available, attributing the event to pilot error, data errors, or aircraft failure is premature. What is clear is that the incident didn’t begin with the tail strike but earlier, when the Boeing 787 failed to accelerate properly during high-speed take-off. That’s the anomaly the BFU must explain.

If confirmed, the acceleration pattern warrants detailed scrutiny. A simple performance error would typically cause consistently poor acceleration, not an intermittent loss and recovery, which points to an external force such as brake or wheel resistance.

The technical cause is only part of the story. With a 240-tonne aircraft, rotation should normally occur well within the available runway—roughly 8,000 feet—depending on conditions. The actual roll-out was abnormally long. So why did four experienced pilots not recognise earlier that the aircraft was using too much runway?

This may reveal weaknesses in current take-off monitoring practices. Pilots are well trained for clear emergencies, such as engine failure or tyre blowouts, but less so for subtle issues where the engines appear normal, airspeed increases, yet acceleration is inadequate.

Unlike approaches, take-offs lack a clear performance checkpoint to confirm that a specific speed has been reached at a particular point on the runway. Modern aircraft can compare actual performance with calculations, but this isn’t usually flagged explicitly.

Hence, VN34 raises questions about procedures and training. Simulator exercises might need to include scenarios involving low or silent acceleration issues to help crews recognise problems early. Greater focus on runway position, expected acceleration, and active performance monitoring could improve safety.

The BFU should be able to resolve much of the technical uncertainty by analysing engine thrust, acceleration, brake pressures, wheel speeds, configuration, V-speeds, and runway position. The CVR will show when and how the crew first noticed the problem, what they discussed, and whether CRM influenced their decisions.

While the visible event was the tail strike, the real issue began earlier—when a heavily loaded Boeing 787 failed to accelerate as expected. The BFU must determine why this happened. But the industry should also consider another crucial question. Why did an exceptionally experienced crew apparently fail to recognise the developing performance deficit when there was still sufficient runway to act?

The lesson may extend well beyond VN34.

For now, assigning blame would be premature. The BFU has not published the recorder-derived sequence, and there is insufficient evidence to determine whether the cause was technical, procedural or human.

If the recorder evidence confirms that the reduced acceleration was detectable well before V1, VN34 should prompt a wider examination of take-off monitoring philosophy, CRM within augmented crews, and low-acceleration recognition and simulator training.

Commercial aviation has become highly proficient at teaching pilots what to do once an emergency has been identified.

VN34 may ultimately remind us that the harder challenge is recognising an emergency developing before the aircraft announces it. That may ultimately prove to be VN34's most important safety lesson.

AI 2379 incident: a speculative introspection.

 Indian aviation continues to face a credibility challenge stemming from operational shortfalls, perceptions of regulatory opacity, institutional fragility, and, in some quarters, allegations of corruption. My earlier evaluation of the AI 2379 incident rested almost exclusively on the technical data available at the time. I normally confine myself to conclusions grounded in recorded evidence. After further reflection, I am making a rare departure into reasoned speculation.

One possibility—if the unverified reports of the pilot’s earlier unconventional experimentation are accurate—is especially troubling. It has been claimed that he had previously switched off all fuel pumps to test whether gravity feed alone would keep the engines running. If a similar experimental inclination had been present on this flight, an alternative explanation for the reported hydraulic event would become conceivable.

The aircraft landed in Delhi at 11:03 IST. Maintenance personnel downloaded the post-flight report at 11:14 IST, which recorded multiple hydraulic-system failures and alerts. Airbus provided its DFDR analysis response at 02:59 on 5 August. Despite that information, the first public statements attributed the altitude excursion to turbulence. The pilot’s formal report and the corresponding tech-log entry have not been released. After media reports citing DGCA sources mentioned a possible hydraulic malfunction, the airline characterised the event as a transient triple hydraulic failure. The pattern of limited disclosure has again fuelled questions about transparency.

Reports indicate the captain was standing behind the first officer at the critical moment. In that position, it is at least physically possible that the hydraulic control switches could have been manipulated, simultaneously deactivating the Green, Blue and Yellow systems. Loss of hydraulic pressure would have left the elevators and ailerons without powered control for approximately four seconds. In damping mode, the ailerons would have drifted towards their zero-hinge-moment positions (reportedly around –13°), producing a pitch excursion.

Faced with the sudden pitch increase and loss of control, the first officer might have pushed the sidestick nose-down, which initially had little effect. Once hydraulic pressure was regained, this input would have taken effect quickly, causing a rapid descent and a negative-G experience. Reports state that, in the process, the captain fell onto the cockpit floor and the cabin crew assisted him back to his seat.

This sequence would also explain another puzzling feature of the event: after the disturbance, the aircraft recovered, remained controllable, and continued to its destination, landing some 90 minutes later. A reversible cockpit action could more readily explain a brief, self-limiting loss of control than a genuine, simultaneous failure of three independent hydraulic systems—an event long regarded as extremely improbable on the A320.

The incident occurred on 4 August. Maintenance downloaded PFR-recorded failures and alarm events, which Airbus corroborated in its report. Pilots’ accounts of what transpired remain unavailable. Meanwhile, social media and TV interviews have dissected the event with little clarity, while the pilots’ union is trying to deflect any possible fallout on the crew, with the AAIB and DGCA remaining mute spectators. Who or what is the AAIB covering up? The recurring opacity around accident and incident investigation and reporting in India is a serious cause for concern. The aim of the powers that be appears to be to allow time to pass and to heal any acrimonious public response. One would normally expect a public statement from the DGCA/AAIB on the interim findings and causal factors under consideration.

This remains speculation. The official investigation by the Aircraft Accident Investigation Bureau, assisted by the French BEA and Airbus, is still examining the DFDR, CVR, maintenance records and human-factor evidence. Until the primary data and a completed causal analysis are published, treat any hypothesis attributing the event to deliberate interference with appropriate caution.

Author: GR Mohan

Air India AI2379: A Transient Triple Hydraulic Event Rather Than a Sustained Failure

 The serious incident involving Air India flight AI2379, an Airbus A320 operating from Phuket to Delhi on 4 August 2026, has been widely described as a “triple hydraulic failure.” However, Airbus’s preliminary DFDR analysis suggests a more complex and technically significant event: a rapid, sequential loss of indicated hydraulic availability across the Green, Blue, and Yellow systems; a temporary loss of elevator and aileron control; and recovery of all three systems within seconds.

According to the publicly reported Airbus analysis, the Green hydraulic system was the first to register a loss of pressure, shortly before 09:32:44. About a second later, the Blue and Yellow systems also lost pressure. Elevator and aileron control then became unavailable for approximately four seconds. During this interval, the aircraft pitched up, and the First Officer applied a full nose-down sidestick input, but the flight-control surfaces initially showed no corresponding response. At about 09:32:51, the Blue system recovered first, followed shortly thereafter by the Yellow and Green systems. Flight-control response returned, the aircraft was stabilised, and the crew subsequently continued the flight to Delhi and landed safely.

This sequence is important because it does not resemble a conventional, sustained triple hydraulic failure involving major fluid loss or permanent loss of pressure generation. A serious leak sufficient to depressurise all three independent hydraulic systems would not normally disappear spontaneously within seconds. Nor would an aircraft suffering continuing total hydraulic loss be expected to regain normal flight-control authority and proceed to destination. The rapid restoration of all three systems therefore points more strongly to a transient common-mode disturbance, a hydraulic-pressure sensing anomaly, an electrical or wiring problem, or temporary removal of hydraulic actuators from service by the flight-control system. Airbus has reportedly requested checks of pressure switches, sensors, associated wiring, hydraulic-system condition, and recent maintenance history to establish whether the recorded pressure losses were genuine or the result of erroneous system indications.

The distinction is fundamental. A major technical difference exists between all three systems registering low or unavailable pressure and all three systems physically failing. Airbus’s preliminary analysis establishes the former, but the root cause remains unresolved.

The pitch-up during the approximately four-second interval also requires careful interpretation. It should not be automatically attributed to “aileron float-up.” Although a control surface deprived of hydraulic actuation may move under aerodynamic loads, the ailerons are primarily roll-control surfaces. Their contribution to pitch would depend on whether both surfaces moved symmetrically, their actual positions, aircraft speed and aerodynamic loading. The elevators and trimmable horizontal stabiliser are therefore equally, if not more, important in explaining the longitudinal response. If elevator servo-control capability was temporarily lost while the stabiliser remained at its cruise trim setting, the aircraft could experience a transient pitch change until hydraulic control was restored.

The A320 is fly-by-wire, but its primary flight controls are hydraulically actuated. The First Officer’s nose-down sidestick input could therefore be recorded electrically even when the elevators were temporarily unresponsive. The reported DFDR sequence—hydraulic indications deteriorating, loss of control-surface response, the aircraft pitching up, a full nose-down sidestick input producing no immediate effect, followed by the restoration of hydraulic capability and control response—matches that architecture.

The investigation will need to correlate Green, Blue and Yellow pressure and pressure-switch states with reservoir quantities, pump status, electrical-bus condition, flight-control computer status, elevator and aileron positions, THS position, sidestick inputs, pitch attitude, pitch rate and normal acceleration. Of particular importance is determining whether hydraulic pressure actually disappeared and, if so, why three independent systems were affected within roughly one second and recovered just as rapidly.

The fact that the aircraft subsequently stabilised, remained fully controllable, and continued to Delhi is one of the strongest indications that this was not a sustained loss of all three hydraulic systems involving major fluid depletion. A genuine fault in one system cannot yet be ruled out, but the available evidence is more consistent with a short-duration, common-mode hydraulic or hydraulic-sensing disturbance that temporarily deprived the aircraft of normal elevator and aileron authority.

At this stage, it is more accurate to describe AI2379 as a transient triple-system hydraulic-availability event rather than a confirmed physical failure of all three hydraulic systems. Airbus’s DFDR analysis has established the sequence and seriousness of the event; identifying the mechanism that caused it remains the investigation's central task.

Author: GR Mohan

AI-171: Transparency, Secrecy and the Purpose of Accident Investigation

 More than a year after the loss of Air India Flight AI-171, the central issue is no longer simply whether the Aircraft Accident Investigation Bureau is continuing its work. The more pressing question is whether the investigation will ultimately yield a technically convincing and publicly accessible explanation of what happened.

The Ministry of Civil Aviation has stated that the investigation is being conducted in accordance with the Aircraft (Investigation of Accidents and Incidents) Rules and with applicable ICAO Standards and Recommended Practices. It has also said that the AAIB has undertaken an extensive examination of the technical, operational, organisational and human factors associated with the accident, and that significant progress has been made in analysing aircraft systems, flight-recorder data and other evidence.

The AAIB, for its part, has reiterated its commitment to professionalism, transparency and investigative rigour.

Those assurances are welcome, but they also invite an obvious question: where is the transparency?

The preliminary report issued in July of last year was necessarily limited in scope and largely factual. This is entirely normal. Preliminary reports are not intended to establish probable cause or provide a complete analysis.

What is more difficult to understand is why, after such an extended period of investigation, so little substantive information has emerged regarding the direction of the technical inquiry.

We are told that aircraft systems have been examined, flight-recorder data analysed and forensic work undertaken. Yet fundamental questions remain unanswered.

Which components were subjected to detailed examination? Which systems were considered potentially relevant? Were any parts sent overseas for specialist analysis? Have those examinations been completed? Has the AAIB received the findings? Have investigators identified any mechanical, electrical, software or system anomalies? More importantly, have significant technical failure modes been conclusively ruled out?

These questions are not speculative distractions. They go directly to the purpose of an aircraft accident investigation.

At the heart of the AI-171 investigation lies a critical, still unresolved issue: how and why did both fuel-control switches move from RUN to CUTOFF shortly after take-off?

Everything else is secondary to that question.

The loss of thrust occurred during one of the most vulnerable phases of flight. If the switches changed state because of a technical or electrical malfunction, investigators must establish and explain the mechanism. If the possibility of a technical malfunction has been excluded, the basis for that exclusion must be demonstrated.

If human action is involved, the conclusion must rest on evidence rather than assumption.

And if the evidence does not allow investigators to determine with certainty how the switches moved, the final report should state this plainly.

There is nothing professionally unacceptable about an inconclusive finding when the evidence genuinely does not permit a definitive conclusion. What would be unacceptable is leaving the central causal question unanswered while relying on confidentiality provisions to avoid discussing the evidence.

This is where the issue of the Cockpit Voice Recorder is particularly important.

There is a sound and well-established reason for protecting raw CVR recordings. Cockpit recordings may contain private conversations, incidental remarks and information entirely unrelated to the accident. Unrestricted publication would serve little safety purpose and could seriously undermine the principles on which protected safety information is collected.

The aviation community should therefore resist simplistic demands that the complete CVR recording be released publicly.

But that is not the real issue.

The crucial distinction is between protecting a raw cockpit recording and withholding information about the safety significance of what that recording reveals.

ICAO provisions protecting CVR material were never intended to prevent investigators from explaining relevant cockpit events in a final accident report. On the contrary, if a statement, action or exchange recorded on the CVR materially assists in understanding the accident sequence, that information forms part of the evidential basis of the investigation.

The public does not need to hear every second of cockpit conversation. But the aviation community needs to understand what the recorder evidence establishes about the accident.

CVR confidentiality must therefore not become a convenient shield behind which critical causal evidence is concealed.

The same principle applies to the Flight Data Recorder and to any forensic examinations of aircraft components or systems.

A professional accident report should not merely state that no technical defect was identified. It should explain how investigators reached that conclusion.

What failure modes were considered? What tests were conducted? What physical evidence was recovered? Which electrical or electronic pathways were examined? Which system logic was assessed? Were switch mechanisms physically inspected? Were wiring, control systems, software functions, or associated components tested? Did the recorder data support or contradict any technical hypotheses?

The credibility of the investigation depends on the ability of technically qualified readers to understand the reasoning.

This is particularly important when a conclusion may point away from mechanical failure and towards human action.

Such conclusions carry significant consequences. They affect the reputation of crew members who cannot speak for themselves. They may influence litigation, manufacturer liability, airline accountability and public perception.

That makes evidential transparency even more important, not less so.

If human action is implicated, the report must establish the sequence convincingly. It should examine not only what appears to have happened but also the circumstances in which it happened: workload, cockpit interaction, procedural design, system ergonomics, possible inadvertent action, startle, cognitive factors, and any relevant organisational influences.

Accident investigation is not strengthened by prematurely reducing a complex event to a single cockpit action.

Nor is it strengthened by excluding technical explanations without demonstrating how they were eliminated.

The recent reports that a copy of the AAIB report may be submitted to the Supreme Court in a sealed cover add another dimension to the debate.

There may be perfectly legitimate reasons for a court to receive certain material confidentially. Judicial proceedings often require sensitive information to be protected, particularly where statutory restrictions apply to recordings, personal information or other investigative material.

But a confidential submission to the Supreme Court and a public aviation accident report serve very different purposes.

a) One serves a judicial process.

b) The other serves aviation safety.

c) A sealed report does not, in itself, prevent a recurrence.

d) It does not inform flight crews.

e) It does not change operating procedures.

f) It does not alert engineers to a system vulnerability.

g) It does not lead manufacturers to modify a design.

h) It does not enable regulators to improve oversight.

And it does not provide the wider aviation community with the lessons that accident investigation is intended to yield.

For that reason, a sealed submission can never be regarded as a substitute for a comprehensive public report.

The primary objective of a safety investigation is not to determine guilt behind closed doors. Its purpose is to reconstruct the sequence of events, identify causal and contributory factors, and recommend measures to reduce the likelihood of recurrence.

That purpose can only be fully achieved when the findings become accessible to those who must act upon them.

a) This is also why prolonged opacity is dangerous.

b) It inevitably creates suspicion.

If no technical defect has been identified, people will naturally ask what the remaining evidence indicates. If investigators have access to the CVR, FDR, physical evidence and forensic results, but the public continues to receive little more than assurances of progress, speculation will fill the vacuum.

Questions will arise about whether the crew, the manufacturer, the airline, the regulator or Government itself has an interest in limiting disclosure.

At present, there is no verified evidence that any of these parties is being protected.

That must be stated clearly.

Criticism of secrecy is justified. An allegation of a deliberate cover-up requires evidence.

But investigative authorities must also recognise that secrecy carries its own consequences. The longer crucial questions go unanswered, the more public confidence erodes.

Trust cannot be sustained indefinitely by statements about professionalism and rigour.

It has to be earned through evidence.

The final report must therefore do far more than announce a conclusion.

a) It must show its work.

b) If a technical failure was considered and rejected, the report should explain the basis for rejection.

c) If an electrical malfunction was investigated, the relevant findings should be presented.

d) If the fuel-control switch design or operation was examined, the results should be discussed.

e) If overseas forensic examinations were commissioned, their significance should be explained.

f) If recorder information establishes a particular sequence, the relevant parameters should be presented clearly enough for informed readers to follow it.

g) If human factors were involved, the analysis should be proportionate, detailed and evidence-based.

h) If organisational, training, regulatory or procedural weaknesses contributed, they should not be obscured by an excessive focus on the final seconds in the cockpit.

i) And if investigators remain unable to determine exactly why the decisive event occurred, the report should say so.

j) There is no need to manufacture certainty simply to produce a neat conclusion.

In aviation safety, an honest admission of limitation is far more valuable than an unsupported assertion.

Transparency should not be confused with indiscriminate disclosure. There is no need to publish irrelevant cockpit conversations or to invade personal privacy. Nor should incomplete or unverified evidence be released prematurely.

But once an investigation reaches its final stage, the evidence required to understand the accident must be disclosed in sufficient detail to withstand technical scrutiny. That is the standard by which the AI-171 investigation should ultimately be judged.

a) The families of those who died deserve meaningful answers.

b) Pilots need to know whether there is an operational lesson.

c) Engineers need to know whether there is a technical vulnerability.

d) Airlines need to know whether procedures require modification.

e) Manufacturers need to know whether design or system changes are necessary.

f) Regulators need to know whether certification, training or oversight require reform.

g) Passengers have a legitimate expectation that a catastrophic accident will result in a clear explanation and tangible safety improvement.

h) These interests are not secondary to the investigation.

i) They are the reason the investigation exists.

j) The public does not need the raw CVR.

k) It does not need speculation dressed up as fact.

l) It does not need premature accusations.

What it needs is a technically complete and intellectually honest account of the accident.

a) If a technical failure has been ruled out, show how.

b) If a system malfunction remains possible, explain why.

c) If human action is implicated, establish this rigorously.

d) If forensic analysis has produced important findings, disclose their safety significance.

e) And if uncertainty remains, acknowledge it.

The AAIB has repeatedly emphasised transparency, professionalism and investigative rigour.

The final report will offer an opportunity to demonstrate all three.

A sealed report may satisfy a procedural or judicial requirement.

But aviation safety is not advanced by sealing away evidence. It advances when evidence is examined rigorously, conclusions are explained convincingly, and lessons are shared openly.

The real test of the AI-171 investigation will therefore not be whether the AAIB says it conducted a thorough investigation. It will be whether the final report shows the aviation community that it did.

a) The investigation must answer the central questions.

b) It must subject its reasoning to professional scrutiny.

c) And above all, it must explain the accident — not bury it.

Author: GR Mohan