The recent crash of Air India flight AI-171 in Ahmedabad has brought renewed attention to the critical role of "black boxes" in aviation accident investigations. The London-bound Boeing 787-8 Dreamliner, carrying 230 passengers and 12 crew members, crashed shortly after takeoff on Thursday, June 12, 2025, killing all but one on board and at least two dozen others on the ground. The aircraft struck a medical college hostel in a residential area, resulting in a devastating scene.

Following the crash, the recovery of the flight's digital data recorder, or "black box," became a top priority. The Aircraft Accident Investigation Bureau (AAIB) recovered the device from a rooftop near the crash site and has begun working to extract the data. But what exactly is a black box, and why is it so crucial in understanding what went wrong?

Despite the name, the "black box" isn't actually black. It's a bright orange-colored device designed to withstand even the worst crashes. More accurately referred to as flight recorders, these devices are essential tools for investigators. They support the overall picture of the event and are an indispensable tool in identifying and addressing the causes and contributing factors of an accident or incident.

A modern flight recorder typically comprises two separate components: the Flight Data Recorder (FDR) and the Cockpit Voice Recorder (CVR). Sometimes, these two devices are combined into a single unit. Both are installed in the tail of the aircraft, the part most likely to remain intact in a crash. They are also equipped with an underwater locator beacon (ULB) that emits an ultrasonic signal when immersed in water, aiding in their recovery, even in underwater accidents.

The FDR meticulously records dozens of parameters related to the aircraft's performance. Modern FDRs can record a vast array of data, from the position of a particular switch to the deflection of an aileron. The Federal Aviation Administration (FAA) requires that the FDR of a commercial aircraft record a minimum of 11 to 29 parameters, depending on the aircraft's size. This data paints a comprehensive picture of the aircraft's mechanical state and actions leading up to an incident. The FDR tracks information such as: Airspeed, Altitude, Engine performance, Flight path, Control-column position, Exterior temperature, Cabin temperature, Flap settings, Magnetic heading, Horizontal stabilizer, Fuel flow, Engine performance, Cabin pressure.

The CVR, on the other hand, captures the audio environment in the cockpit. This includes conversations between pilots, radio transmissions, and any other sounds or alarms. The CVR is typically connected to microphones in the pilots' headsets and an area microphone in the cockpit. Modern CVRs can store over two hours of audio, providing a detailed record of the crew's interactions and any audible warnings or anomalies. Trained investigators listen closely to this recorder to understand what the plane's engine was doing. For example, a recorder might pick up a stall warning sound or may reveal that the engine wasn't operating correctly. A recorder can also help investigators determine whether flight crew was aware that something was wrong before the plane went down.

The data from the black box is invaluable in determining the cause of an accident. By analyzing the flight data and cockpit conversations, investigators can identify potential factors such as human error, mechanical failure, or environmental conditions. The objective nature of the data provides a solid foundation for arguments, often becoming the linchpin in determining liability and accountability in complex aviation litigation scenarios. The black box data can verify reckless or impaired driving behaviors, such as excessive speeding or harsh braking and can also help establish fault against manufacturers, if a malfunction, such as brake failure or delayed airbag deployment, contributed to injuries.

While the black box is a crucial tool, decoding the data requires advanced equipment and expertise. The process can take weeks or even months. However, the insights gained from the black box are essential for improving aviation safety and preventing future accidents. Following the analysis of black box data, airlines and manufacturers can issue safety advisories, modify aircraft design, or enhance pilot training programs.