Black Boxes Recovered: What The FDR, CVR Could Reveal About Air India Flight's Final Moments

Last Updated:June 16, 2025, 11:32 IST

Air India AI171 Flight Black Box: From cockpit warnings to engine behaviour, the black boxes may hold the key to understanding what brought down AI-171

Investigators are examining multiple sources of data and footage to determine what caused the crash. (PTI Image)

Air India AI171 Flight Black Box: With both the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) recovered from the wreckage of Air India Flight AI-171, investigators are now focusing on decoding what exactly went wrong in the final moments before the crash near Ahmedabad airport on June 12. These two devices—together often referred to as “black boxes"—are central to every modern air crash probe. But what do they record, and how do they help?

Here’s a detailed look at what the CVR and FDR do, how they differ, and why both are vital to the investigation into India’s deadliest aviation disaster in over a decade.

What Does The Cockpit Voice Recorder Do?

The Cockpit Voice Recorder, or CVR, captures all audible activity inside the cockpit. This includes conversations between the pilots, communication with air traffic control, cockpit alarms, automated warnings, and ambient background sounds such as engine noise and switches being activated. Modern CVRs are designed to record up to two hours of cockpit audio in a continuous loop.

If there are any signs of human error, stress, distraction, or confusion, the CVR often reveals it. In many past crash investigations, the CVR has helped establish what the crew was dealing with in real time, and whether they followed emergency protocols.

What Does The Flight Data Recorder Do?

The Flight Data Recorder stores technical data about the aircraft’s behaviour and systems throughout the flight. This includes readings on altitude, speed, heading, vertical acceleration, and control surface positions like rudder, ailerons, and throttle. It also logs engine performance indicators, autopilot engagement, and any system alerts triggered during the flight.

FDRs can store at least 25 hours of such data, logging multiple parameters every second. When decoded, this information allows investigators to reconstruct the aircraft’s precise movements and detect anomalies that could point to mechanical failure, system errors, or instability in flight.

What’s The Difference Between CVR And FDR?

The CVR and FDR work together but serve very different purposes. The CVR focuses on audio inside the cockpit and captures the human element of flying—what the pilots said, heard, and how they responded in the moment.

The FDR, on the other hand, records the technical side of the story: how the aircraft performed, what systems were active, and whether there were any mechanical irregularities.

While the CVR helps investigators understand how the crew reacted to a developing situation, the FDR offers insight into what may have caused it. Both sets of data are analysed in sync to build a complete picture of the flight.

Why Are CVR And FDR Crucial To The Ahmedabad Crash Probe?

In the case of the Air India AI-171 crash, statements by the Press Information Bureau (PIB) and the Prime Minister’s Office (PMO) on Sunday said that the CVR had been retrieved from the crash site. Investigators had earlier found the FDR, one of the black boxes, at the crash site.

Their analysis will likely be central to understanding whether the Boeing 787 suffered a technical failure, if the crew made a distress call, or if external factors such as a bird strike or engine malfunction contributed to the incident.

How Long Does Black Box Analysis Take?

The timeline for decoding CVR and FDR data depends on their physical condition and the complexity of the crash. If the recorders are intact and the data is recoverable, preliminary analysis can begin within a few days. However, a full investigation often takes weeks or months.

Most countries, including India, follow the international convention of releasing a preliminary report within 30 days, with a final report issued after a comprehensive technical review.

How CVR And FDR Data Is Protected And Accessed

Once recovered, both recorders are sent to a specialised laboratory—either within the country or, in some cases, abroad—for data extraction. In India, this is handled by the Aircraft Accident Investigation Bureau (AAIB) or outsourced to certified international labs if needed. The devices are designed to withstand high-impact crashes, intense fire, and deep water pressure. Even if the outer casing is damaged, the memory units are often intact and retrievable.

Strict access protocols are followed. Only authorised accident investigators are permitted to examine the raw data. In the case of cockpit voice recordings, privacy norms are observed, and such recordings are rarely made public. The purpose of accessing the data is not to assign blame, but to understand what happened and prevent future incidents.

Why This Data Matters

While speculation around the cause of the Ahmedabad crash continues, only the CVR and FDR can provide verified answers. These recorders are not just tools for accountability, they are essential for improving aircraft design, refining pilot training, and strengthening emergency response protocols. With the data now in the hands of investigators, the focus will shift from recovery to evidence and explanation.

How CVR And FDR Have Helped In Past Indian Crashes

Black box data has played a pivotal role in solving several major air accidents in India.

According to the official Court of Inquiry report submitted to the Directorate General of Civil Aviation (DGCA), in the 2010 Air India Express crash in Mangalore, the Cockpit Voice Recorder revealed that the pilot was disoriented after a prolonged nap and ignored multiple automated warnings during the approach. The Flight Data Recorder confirmed that the aircraft touched down significantly beyond the intended zone on the table-top runway, leaving insufficient distance to stop, which led to the fatal overrun.

Similarly, in the 2020 Air India Express crash in Kozhikode, black box data—analysed as part of AAIB’s final report—showed that the pilots attempted to land in challenging weather conditions and that the aircraft touched down significantly farther down the runway than the recommended touchdown zone. Both the CVR and FDR findings led to regulatory changes by the AAIB and DGCA, including enhanced training for pilots operating on tabletop runways and stricter protocols for landing during adverse weather conditions.

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The News Desk is a team of passionate editors and writers who break and analyse the most important events unfolding in India and abroad. From live updates to exclusive reports to in-depth explainers, the Desk d...

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