Two U.S. pilots’ associations are claiming that Boeing Co. failed to warn of a safety issue on the company’s 737 Max aircraft that has been linked to the deadly crash in Indonesia.


Both Boeing and the Federal Aviation Administration issued directives last week notifying flight crews about the plane’s system that is designed to provide extra protection against pilots losing control. Aviators, unions, and training departments realized shortly after that none of the documentation for the 737 Max aircraft included an explanation.


In a statement to Bloomberg, Jon Weaks, president of the Southwest Airlines Pilots Association told the publication, “we don’t like that we weren’t notified.”


Dennis Tajer, a 737 captain and spokesperson for the Allied Pilots Association at American Airlines Group Inc., echoed Weaks’ concerns.


This is not about silos and layers of bureaucracy, this is about knowing your airplane,” Tajer told Bloomberg. “We will always be eager and aggressive in gaining any knowledge of new aircraft.”


Few details have emerged about the underlying cause of the Lion Air crash in the sea near Jakarta on Oct. 29 that killed all 189 people aboard.


Indonesian investigators said that an erroneous sensor prompted the plane’s computers to push the aircraft into a steep dive. A new safety measure added on the Max models to prevent pilots from losing control is what caused the plane to point downward, according to the FAA and Boeing.


According to a report from Skift, Boeing and the FAA said in the directives that an existing procedure could have halted the dive. The FAA ordered airlines to add an explanation into flight manuals.