PHILADELPHIA (WPVI) -- After the second deadly crash in less than five months, Boeing's best-selling passenger jet is facing increasing scrutiny and it threatens to tarnish the plane maker's reputation.
Boeing's 737 Max was launched in 2011 as the fourth generation 737.
The crashes of two new jets in such a short time has brought extraordinary attention on the 737 Max 8, it's operators and national regulators.
Although Ethiopian Airlines, China & Indonesia have grounded all planes of that type, the Federal Aviation Administration issued a continued airworthiness notification. As such, two U.S. airlines that fly the 737 Max 8, American Airlines and Southwest, say they will continue to do so. Some passengers who flew on such a plane late Monday into Philadelphia from Phoenix say for now, they're not concerned.
"I have no problem, I trust Boeing and I fly a lot on Southwest and I flew this plane a lot, so I think there's not a problem," said Adam Weingard of Los Angeles.
"I've flown with Southwest a lot, and I've never had any trouble. The pilots are really good about letting us know when they're having trouble so, I feel confident flying with them," said Amanda Hoffman of Lancaster.
While investigators have still not determined the cause of the two crashes. Aviation experts say there are similarities between the two crashes. Both crashed shortly after takeoff.
"This is a very, very serious problem," said aviation expert, Arthur Wolk.
Wolk points out that investigators in the first crash of a Lion Air 737 Max 8 suspect the crash was caused by an angle of attack sensor, an AOA, that transmitted incorrect data to a kind of auto-pilot system, called the Maneuvering Characteristics Augmentation System, that forced the plane's nose down.
"It thinks it's going to stall. It thinks the nose is going to go up so high, it's gonna lose airspeed and quit flying. So what it does is it pitches the nose down, when it pitches the nose down, now the crew is literally between a rock and a hard place," said Wolk.
"What should airlines be doing right now that are using these planes?" asks Action News reporter Dann Cuellar.
"They have to ground them," Wolk said. "It's wrong. You're exposing 186 people at a time to this risk."
Boeing's new jet facing scrutiny after second fatal crash