Boeing held back information about possible malfunctions with the new flight-control feature that’s believed to have played a role in the Lion Air jet crash that killed 189 people in Indonesia last month, The Wall Street Journal reports. FAA officials and safety experts involved in the investigation told the Journal that the automated stall-prevention system on the Boeing 737 MAX 8 and MAX 9 models can kick in and send a plane into a steep dive even if pilots are manually flying the aircraft. Investigators are still working to determine if that is what caused the Lion Air flight out of Jakarta to plunge into the Java Sea on Oct. 29. Boeing warned airlines about that risk in a safety bulletin issued just days after the crash—but pilots who fly the latest models for U.S. airlines were reportedly left in the dark about not only the potential risks but the new system itself. “It’s pretty asinine for them to put a system on an airplane and not tell the pilots who are operating the airplane, especially when it deals with flight controls,” Capt. Mike Michaelis, chairman of the safety committee for the Allied Pilots Association, told the Journal. An unnamed high-level Boeing official quoted in the report said the company had decided to leave out certain details about the new models so as not to overwhelm average pilots with more information than they would need. Boeing has yet to comment on the claims but said the company is “taking every measure” to understand what caused the Lion Air crash.