By Kyle Arnold

The Dallas Morning News

The unions for American Airlines’ flight attendants and pilots say they are worried about the safety of the 737 Max after “alarming” testimony from Boeing’s CEO before Congress last week.

The flight attendants’ union chief, Lori Bassani, said she has concerns over “serious breakdowns in the supervision of the Boeing 737 Max” after hearing Boeing CEO Dennis Muilenburg testify.

The Association of Professional Flight Attendants, which represents 28,000 workers at American Airlines, sent a letter to Muilenburg on Thursday with her worries and is joining a growing group of critical workers who could soon have to fly on the beleaguered 737 Max.

“The 28,000 flight attendants working for American Airlines refuse to walk onto a plane that may not be safe and are calling for the highest possible safety standards to avoid another tragedy,” Bassani said in the letter. “Our lives are not for sale.”

Dennis Tajer, a spokesman for the Allied Pilots Association that represents American Airlines pilots, said Muilenburg’s testimony was concerning to those flying planes, too.

“There were areas that were alarming and another crack on the fragile glass of this company,” said Tajer, a 737 Max captain for American Airlines. “It’s clear that the certification system failed. It failed for Boeing and it failed for the FAA.”

Tajer also took issue with Muilenburg’s comments that training is only needed for pilots to fly the airplane, not to diagnose problems. Boeing employees lobbied the Federal Aviation Administration to remove mentions of the MCAS system from pilot training manuals.

“(Muilenburg) said sometimes less information in the manual is more safe,” Tajer said. “He’s wrong on that.”