The family of the Indonesian co-pilot of a Lion Air flight that crashed in October, killing all 189 on board, has filed a wrongful death lawsuit against Boeing in Chicago, adding to litigation piling up against the manufacturer in its hometown.

The lawsuit, filed on Friday in the Circuit Court of Cook County, Illinois, alleges that the Lion Air-operated Boeing 737 MAX 8 was unreasonably dangerous because its sensors provided inconsistent information to both the pilots and the aircraft.

Boeing declined to comment on pending litigation.

Lion Air Flight 610 crashed into the Java Sea after take-off from Jakarta on October 29.

The complaint was filed on behalf of the widow and three children of the co-pilot, who uses a single name, Harvino. The family is from Jakarta.

The lawsuit also alleges that the instruction manuals provided by Boeing with the two-month-old plane were insufficient, leading to the death of the pilots, crew and passengers.

In a statement, law firm Gardiner Koch Weisberg & Wrona said Harvino and Flight 610 Captain Bhayve Suneja were both experienced pilots, having logged more than 5000 and 6000 flight hours prior to the disaster.

At least two other lawsuits have been filed against Boeing in Chicago by the Lion Air victims.

A preliminary report by Indonesian investigators focused on airline maintenance and training and the response of a Boeing anti-stall system to a recently replaced sensor but did not give a cause for the crash.

One of the investigators, Nurcahyo Utomo, told reporters it was too early to determine whether or not a new version of the anti-stall system, which was not explained to pilots in manuals, was a contributing factor.

-AAP