(CNN) — The parents of Dr. Rio Nanda Putrama, who died in the Indonesia airplane disaster last month that killed all 189 passengers on board, have sued Boeing for its alleged “unsafe design” of the 737 Max 8 aircraft.

The lawsuit, filed Thursday in the Circuit Court of Cook County, Illinois, where Boeing is headquartered, centers on a new safety feature that can cause the 737 Max 8 aircraft to “auto-dive” in certain situations.

The suit alleges this is a change from prior Boeing 737 designs and that the company failed to communicate the change.

“At no relevant time prior to the crash…did Boeing adequately warn Lion Air or its pilots of unsafe condition caused by the new ‘auto-diving’ design,” the suit alleges.

Putrama was flying to Pangkal Pinang in Indonesia to get married, according to his parent’s lawyers.

It is the latest headache for Boeing, which has faced mounting pressure in the wake of the crash.

On Wednesday, a top Lion Air official joined a US pilots’ group in alleging the company failed to warn pilots about the potential hazards of the new safety feature implicated in the crash.

Zwingli Silalahi, Lion Air’s operational director, said the manual did not tell pilots that in certain situations, the plane’s stall-prevention system could automatically trigger a response, such as lowering the airplane’s nose, to prevent or exit a stall.

“We don’t have that in the manual of the Boeing 737 Max 8. That’s why we don’t have the special training for that specific situation,” Zwingli said.

Representatives from American, United and Southwest airlines each said Friday that Boeing did not include information in its flight crew manual that explained the functions of new features found on the aircraft.

Because that information was not spelled out with specificity, the airlines said, their pilots were not clear on all of the functionality of a key system in the aircraft.

The airlines say Boeing has now communicated what the new features are and how they work, and pilots are aware of them as well. American and United airlines said the revelation of new information will not require additional pilot training.

Investigators are examining whether a sensor on the outside of the plane transmitted incorrect data that could have triggered the stall-prevention system.

The airline’s claims come after Boeing was similarly accused Tuesday by the Allied Pilots Association (APA), a labor union that represents American Airlines pilots, of withholding information about the potential danger of the plane’s new features. On Thursday, American Airlines backed up their pilots’ claims.

Lion Air Flight 610 crashed shortly after taking off from the Indonesian capital of Jakarta on October 29. Investigators believe the Max 8 plane may have experienced problems with several sensors.

Boeing said last week that a safety bulletin issued to aircraft operators in the wake of the crash was merely meant to reinforce existing procedures. Both Lion Air and the APA reject the company’s assertion.

“They (Boeing) didn’t provide us all the info we rely on when we fly an aircraft,” Capt. Dennis Tajer, a spokesman for the APA group, told CNN on Tuesday. “The bulletin is not reaffirming, it’s enlightening and adding new info.”

Zwingli added that Boeing’s safety bulletin did not suggest additional training for pilots operating that aircraft. “We didn’t receive any information from Boeing or from regulator about that additional training for our pilots,” he said.

Zwingli said that if the result of the ongoing investigation — conducted by Indonesia’s National Transportation Commission, the US National Transportation Safety Board and Boeing — found that additional training was necessary, Lion Air pilots would undertake it.

On Wednesday, a Boeing spokesperson said in an email that the company could not “discuss specifics of an ongoing investigation” and that the company had “provided two updates for our operators around the world that re-emphasize existing procedures for these situations.”

“We are confident in the safety of the 737 MAX. Safety remains our top priority and is a core value for everyone at Boeing,” the spokesperson said.

The head of the Directorate of Airworthiness and Aircraft Operations (DOAAO) at the Indonesian Transportation Ministry told CNN on Wednesday that the agency was in the process of intensive discussions about additional training for the pilots who fly the Max 8 planes, but did not elaborate on what any additional training would involve.

On Tuesday, the APA said while there were no immediate safety concerns about the Max 8 planes, “the fact that this hasn’t been told to pilots before calls into question what other info should we know about this aircraft.”

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