WASHINGTON (NEXSTAR) -- Nevada Congresswoman Dina Titus says the Federal Aviation Administration has a credibility problem.
"You were in bed with those that you were supposed to be regulating," Titus said.
The U.S. was the last country in the world to ground the Boeing 737 MAX 8 jets after two crashes just months apart killed 346 people.
"The public perception was that it took so long for us to do it, we were the last ones to do it, because FAA was just too cozy with Boeing," Titus said.
Preliminary investigations show a link between both crashes and an anti-stall feature in the MAX jets called the MCAS system.
Oregon Congressman Peter DeFazio says Boeing knew for a year about the problems before notifying the FAA.
A new audio recording obtained by CBS News reveals that American Airlines pilots confronted Boeing about problems before the second crash.
"In the US the 737 MAX will return to service only when the FAA's analysis of the facts and technical data indicate that it's safe to do so," Acting FAA Administrator Daniel Elwell said.
Some lawmakers suggest Boeing has far too much control over the safety certification process and that needs to change.