The chief U.S. aviation regulator said he was very encouraged by a one-day discussion with his counterparts from around the world on the steps needed to return Boeing Co.’s grounded 737 Max jetliner to service, including the need for additional pilot training.

The meeting was “both comprehensive and constructive,” said Federal Aviation Administration acting chief Daniel Elwell, addressing reporters Thursday night after the meeting in Texas concluded.

“It was truly a remarkable day,” Elwell said in some of his most upbeat comments since the plane was grounded on March 13 following the second fatal crash in less than five months. “It’s unprecedented in my career. It was exceedingly positive, exceedingly constructive and productive. I’m very encouraged.”

Attendees included China, which moved to ground the plane days before FAA did, as well as Canada, Australia, Singapore and the European Aviation Safety Agency. In all, delegates from 31 individual countries participated in the meeting in Fort Worth, Texas.

Transport Canada officials found the Texas gathering to be “a beneficial session” at which global regulators formed a general consensus that there is no time frame to work against for returning the Max to service, said Nicholas Robinson, the agency’s director general civil aviation.

“This is not about meeting a deadline, this is about getting safety done properly,” he said on a teleconference with reporters.

Boeing is still finalizing an update for software implicated in both crashes, along with accompanying changes to training. But in the meeting with global regulators, the FAA shared its framework for the safety analysis it will use to evaluate the proposals, Elwell said. The agency also detailed the extensive steps necessary to get the planes back into service, which have missed maintenance checks while sitting on the ground.

Elwell reiterated comments from earlier in the week that the FAA has no timetable for recertifying the plane. In addition to its own review, the U.S. regulator has created an outside panel of experts from the Transportation Department, the Air Force and the National Aeronautics and Space Administration to look over its shoulder and make suggestions.

There are signs that some aviation regulators plan to go slower than the FAA. Both EASA and Canada, for example, have said they plan to conduct additional reviews to ensure that the plane is safe.

Robinson said Transport Canada will review Boeing’s software changes to the Max and the FAA’s certification of them through a “rigorous” validation process, which may require further work by the company or FAA. “We have full confidence in the FAA and the process they have in place.”

It’s still too soon to determine if the 737 Max will require simulator training for pilots, which remains an option Canada may mandate, Robinson said. Regulators must first evaluate Boeing’s software changes. “I would suggest that there’s many factors we have to consider before we determine what sort of training will be required,” he said.

An FAA panel that advises the agency on pilot training issued a draft report in April finding that simulator sessions weren’t necessary for the 737 Max. The report wasn’t final and the agency hasn’t made a decision.

The FAA discussed the need for whether simulator training specifically on the automated system that drives down the plane’s nose would be required, said Elwell, a former American Airlines pilot who has also worked for the U.S. airlines’ trade group.

When asked whether other nations might request such training, Elwell said he wasn’t aware of it. “No individual country stood up and said we need to have simulator training,” he said.

It’s possible the FAA won’t require simulator training before returning the plane to service, but will mandate related simulator assignments during recurrent training. Airline pilots must demonstrate flying skills as frequently as every six months.

Once the fix is in place, the risks of a malfunction should be lower and that may reduce the need for specialized simulator training, Elwell said. He cautioned that FAA has made no decisions on the issue.

“Our team, our airline customers, and regulators place the highest priority on the safety of the flying public,” Boeing said in a statement. “Once we have addressed the information requests from the FAA, we will be ready to schedule a certification test flight and submit final certification documentation.”

The FAA grounded the 737 Max models on March 13 after evidence emerged that a crash three days earlier of an Ethiopian Airlines flight that had just taken off from Addis Ababa had involved an erroneous activation of a device that repeatedly commanded the plane to dive.

The U.S. was one of the last countries to halt flights on the plane. Elwell has said the FAA needed hard evidence of a link between the two accidents, while other countries said they were acting out of caution.

The same system, Maneuvering Characteristics Augmentation System or MCAS, was also activated in the Oct. 29 crash of a Lion Air 737 Max leaving Jakarta.

Chicago-based Boeing has developed a software fix that won’t allow MCAS to push down a plane’s nose more than once and it will rely on data from two sensors instead of one in an attempt to lower the chances that a single malfunction can trigger it.

A representative for Australia’s Civil Aviation Safety Authority, which sent a senior manager to the meeting in Texas, said it wasn’t appropriate to comment on the talks.