The families of four people who died in the June 12 crash of Air India Flight AI171 have filed a lawsuit against US aircraft maker Boeing and aerospace supplier Honeywell, alleging that defective cockpit fuel switches were responsible for the accident that killed 260 people.

The lawsuit, submitted in Delaware Superior Court on Tuesday, says the crash happened just seconds after the Boeing 787 Dreamliner took off from Ahmedabad for London, due to a faulty design of the aircraft’s fuel cutoff switches.

Honeywell produced the switches, which were cleared by the US Federal Aviation Administration. While the FAA has said the switches themselves do not seem to have directly caused the crash, the lawsuit argues that their design and placement made them vulnerable to accidental use.

The complaint is seeking unspecified compensation for the families of Kantaben Dhirubhai Paghadal, Naavya Chirag Paghadal, Kuberbhai Patel, and Babiben Patel, who were among the victims, according to Reuters.

According to the Aircraft Accident Investigation Bureau of India, the Dreamliner took off normally before both engines lost power.

A cockpit voice recorder captured one pilot asking, “Why did you shut off the fuel?” and the co-pilot replying, “I did not.”

Investigators discovered that the fuel switches had been moved to “CUTOFF,” cutting power to both engines. Although the crew changed them back to “RUN” within 14 seconds, which triggered an automatic engine restart, the aircraft had already lost the thrust it needed.

The plane went into a steep descent and crashed into a nearby building only 32 seconds after takeoff. CCTV footage showed the Ram Air Turbine deploying, which is a backup power source used when both engines fail. The AAIB report also confirmed there were no bird strikes, as no signs of bird activity were found in the area.

Out of the 229 passengers, 12 crew members, and people on the ground, only one passenger survived.

The initial investigation also showed that Air India had not carried out every recommended inspection for this aircraft model. Maintenance records revealed that the throttle control module, which holds the fuel switches, was replaced in 2019 and again in 2023 on this plane.

Even so, the AAIB noted that “all applicable airworthiness directives and alert service bulletins were complied with on the aircraft as well as engines,” which indicated that regulatory standards were followed.

The lawsuit, however, claims that placing the switches just below the thrust levers “effectively guaranteed that normal cockpit activity could result in inadvertent fuel cutoff.”

Aviation safety specialists told Reuters that the switches’ design makes such accidental use very unlikely.

Legal experts also said that while aviation accidents usually happen due to several combined causes, lawsuits against aircraft manufacturers are common because airlines have liability limits that do not apply to plane makers, Reuters reported.

Fuel control switches are responsible for managing the fuel supply to an aircraft’s engines, and they are crucial during engine start-up, shutdown, and emergency situations in flight. On the Boeing 787-8 Dreamliner, these switches are located below the thrust levers.

If the switches are moved to “CUTOFF,” the engines immediately lose power. Aviation engineers say the switches are made to avoid accidental use.

However, once they are moved, the effect is instant, leaving little time to recover, as tragically shown in the Air India crash.