The families of four victims of the June 12 crash of Air India Flight AI171 have filed a lawsuit against US planemaker Boeing and aerospace supplier Honeywell, alleging that faulty cockpit fuel switches caused the deadly accident that killed 260 people. The complaint, lodged in Delaware Superior Court, claims the accident occurred seconds after the Boeing 787 Dreamliner took off from Ahmedabad for London due to a defective design of the aircraft’s fuel cutoff switches.

Honeywell manufactured the switches, which were approved by the US Federal Aviation Administration (FAA). While the FAA has said the switches themselves do not appear to have caused the crash, the lawsuit contends that their design and placement made them prone to accidental activation. The lawsuit seeks unspecified damages on behalf of the families of the victims.

According to India's Aircraft Accident Investigation Bureau (AAIB), the Dreamliner took off normally before both of its engines lost power. A cockpit voice recorder captured one pilot asking the other, “Why did you shut off the fuel?” to which the co-pilot responded, “I did not.” Investigators found that the fuel switches had been flipped to “CUTOFF,” cutting power to both engines. Though the crew reset them to “RUN” within 14 seconds, triggering an automatic engine relight the aircraft had already lost critical thrust. The plane entered a steep descent, crashing into a nearby building just 32 seconds after takeoff.