Investigators in India are studying the black boxes of a Boeing 787 Dreamliner after recovering them from the aircraft wreckage to ascertain the cause of last week’s plane crash that left at least 270 people dead.

The black boxes will provide cockpit conversations and data related to the plane’s engine and control settings to investigators and help them in determining the cause of the crash.

The London-bound Air India aircraft, a Boeing 787 Dreamliner, crashed on a medical college hostel soon after taking off from the western city of Ahmedabad. Only one passenger survived the crash, while 241 people on board and 29 on the ground were killed in one of India’s worst aviation disaster in decades.

Experts from India’s Aircraft Accident Investigation Bureau are probing the crash with assistance from the U.K., the U.S. and officials from Boeing.

Black box data is crucial

Amit Singh, a former pilot and an aviation expert, said the recovery of the flight data and cockpit voice recorders, or black boxes, are crucial to piece together the sequence of events.

The cockpit voice recorder records pilots’ conversation, emergency alarms and any distress signal made before a crash. The plane’s digital flight data recorder stores information related to engine and control settings. Both devices are designed to survive a crash.

“The data will reveal everything,” Singh said, adding that the technical details could be corroborated by the cockpit voice recorder that would help investigators know of any communication between air traffic control and the pilots.

India’s aviation regulatory body has said the aircraft made a mayday call before the crash.

Singh said the investigating authorities will scan CCTV footage of the nearby area and speak with witnesses to get to the root cause of the crash.

Additionally, Singh said, the investigators will also study the pilot training records, total load of the aircraft, thrust issues related to the plane’s engine, as well as its worthiness in terms of past performances and any previously reported issues.

Investigation into the crash could take time

Aurobindo Handa, former director general of India’s Aircraft Accident Investigation Bureau, said the investigators across the world follow a standard UN-prescribed Manual of Accident Investigation, also called “DOC 9756,” which outlines detailed procedures to arrive at the most probable cause of a crash.

Handa said the investigation into last week’s crash would likely be a long process as the aircraft was badly charred. He added that ascertaining the condition of the black boxes recovered from the crash site was vital as the heat generated from the crash could be possibly higher than the bearable threshold of the device.

The Indian government has set up a separate, high-level committee to examine the causes leading to the crash and formulate procedures to prevent and handle aircraft emergencies in the future. The committee is expected to file a preliminary report within three months.

Authorities have also begun inspecting and carrying out additional maintenance and checks of Air India’s entire fleet of Boeing 787 Dreamliners to prevent any future incident. Air India has 33 Dreamliners in its fleet. The plane that crashed was 12 years old. Boeing planes have been plagued by safety issues on other types of aircraft. There are currently around 1,200 of the 787 Dreamliner aircraft worldwide and this was the first deadly crash in 16 years of operation, according to experts.