Ahmedabad plane crash: Here is how air accidents are investigated

With at least 170 killed in the Ahmedabad plane crash, it is set to be one of the worst aviation disasters in the country.

The plane crashed shortly after takeoff in Ahmedabad’s Meghani area. The plane was carrying 242 passengers from India.

The air crash investigation will start as soon as the conclusion of the rescue operation at the site of the crash.

As per established norms, the authorities of the country in whose jurisdiction the accident takes place takes the lead in the investigation. Other countries are also often part of the investigation, such as countries whose nationals are involved in the accident and where the airline and the plane’s manufacturer are based.

In India, the responsibility of air accident investigation is with the Aircraft Accident Investigation Bureau (AAIB) under the Ministry of Civil Aviation (MoCA).

Here is how air crash investigations are conducted.

How air crash investigations start

The first step in the investigation is securing the site and collecting all available physical evidence and documenting it. This involves photography and videography of the site and debris.

Investigators salvage as much debris of the aircraft as possible. The debris is stored properly at a secure site. They also map the distribution of debris.

All of this helps them understand the trajectory of the plan, when the plane started disintegrating, how it disintegrated, and how the final impact was, including its angle and force, among other things.

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Investigators conduct interviews with witnesses and survivors to get firsthand information.

Investigators collect all the documents related to the aircraft, crew, and their recent flights for forensic analysis. They also collect samples of all deceased and test them with samples of family members of those onboard for the identification and handover of bodies.

‘Black box’ holds key to understanding air crashes

As soon as investigators reach the site, they start searching for the ‘black box’ of the aircraft.

Black box consists of a cockpit voice recorder (CVR) and flight data recorder (FDR).

The CVR consists of many microphones in the cockpit that record all the sounds ranging from spoken words to even low clicking of switches. The recordings are critical in understanding the circumstances of the crash as they help understand what was going on inside the cockpit through the flight. The CVR has recordings of pilots and crew, sounds and warning from instruments, and engine sounds, among others.

The FDR consists of many sensors in the plane that track the time, altitude, speed, and fuel.

Together, the CVR and FDR help investigators reconstruct the flight trajectory, including the descent into accident.

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In case the black box is damaged, the investigators may ask the aircraft or device’s manufacturer for help in accessing the data. They may also rope in international partners with expertise in the matter. For example, Ethiopian investigators probing the Ethiopian Airlines crash of 2019 roped in France’s Bureau of Enquiry and Analysis for Civil Aviation Safety for help which is considered to be one of the world’s most experienced air crash investigation agencies.

Who probes air crashes? How is report prepared?

In India, the Aircraft Accident Investigation Bureau (AAIB) is the dedicated agency to probe air crashes.

While the country where the accident takes place takes the lead in investigation, other countries are also often part of the investigation in various capacities.

These countries are usually the countries where the aircraft is registered, where the airline is headquartered, where the aircraft designer is headquartered, and where the aircraft was made. Countries where critical components of the plane were made, such as engines, may also be part of the investigation.

Within 30 days of the accident, investigators submit a preliminary report to the International Civil Aviation Organization, the United Nations (UN) agency for air travel.

Usually, the final report is expected within a year, but updates are usually given at significant dates, such as the one-year anniversary, if investigation stretches for a long period of time.

The purpose of such a report is not to assign blame but to find reasons for the crash with the purpose of improving aviation safety. The reasons may range from human error of pilots or air traffic controllers to equipment malfunction. Corrective actions may range from correcting any flaws in equipment or improving training of pilots or sanitising the area of birds.