There are new signs that the Boeing 737 Max won't be flying passengers for a while after the Federal Aviation Administration met with foreign regulators in Fort Worth Thursday to discuss the jet's future. Features on the plane may have been a factor in two deadly crashes in the past year.

Acting FAA administrator Daniel Elwell told CBS News' Kris Van Cleave the agency does not have a timeline for when they expect to get the 737 Max flying passengers again.

"We have to finish our system safety analysis, there will be some test flights that have to be done," Elwell said. "And when we're convinced that the 737 Max is safe to fly again, we will lift the prohibition order."

Aviation regulators from 33 countries where the Boeing 737 Max flies came to a FAA facility in Fort Worth Thursday. At a closed-door meeting Elwell laid out the agency's plan for certifying the Max as safe. Some countries did not attend – a sign the Max may start flying first in the U.S. while the world watches.

"None of us are going to lift the prohibition on the 737 Max until its safe to do so," Elwell said.

As Elwell makes his case for the rest of the aviation world to trust the FAA when the agency is ready to deem the 737 Max ready to fly again, new research shows Americans are leery about setting foot on the Max – even when it's cleared to fly.

A new study by Atmosphere Research Group found only about 1 in 5 people surveyed would definitely fly on a Max in the first six months of its return to service. Roughly half said they'd be unlikely to get on board.

"So it's important that the FAA doesn't regulate by survey, right? We regulate … where in the last 10 years in the United States, 90 million flights, 7 billion passengers carried with one fatality," Elwell said.

Pressed on the how they'll handle public opinion that the plane isn't safe, Elwell said, "Yes we need to be concerned if the public is concerned about flight, yes is that bothersome? It's bothersome. But we can't respond specifically to that concern when it comes to setting safety standards."

It could be the fall before the plane has passengers on it. Boeing said it's still answering information requests from the FAA about the software.

Boeing has hired a PR firm to help restore trust in the Max and plans to rely heavily on pilots as a show of confidence in the plane but some pilots are saying they're not interested in being arm candy.