FORT WORTH, Texas >> Representatives from more 30 countries met with Federal Aviation Administration officials today to hear the U.S. regulator’s approach to determining how soon the Boeing 737 Max can resume flying after two crashes that killed 346 people.

Before the meeting, acting FAA Administrator Daniel Elwell declined to give a timetable for the plane’s return. He hinted it could be several months, saying that even October — a later return than airlines expected — might not be realistic.

The meeting is crucial to the U.S. agency’s hopes of convincing other regulators around the world to lift their bans on the plane soon after the FAA does.

Among those scheduled to attend were regulators from China, Europe and Canada, as well as officials from Indonesia and Ethiopia, sites of the two crashes that occurred before the Max was grounded worldwide in March.

Boeing is fixing flight-control software that in each accident pushed the plane’s nose down based on faulty readings from a single sensor. It will tie the system to more than one sensor and make it less powerful — pilots for Lion Air and Ethiopian Airlines were unable to counter the system’s automatic nose-down pitch.

Elwell has said he hopes other regulators will lift their bans on the plane soon after FAA does.

However, regulators in China, the European Union and Canada have said they plan to conduct their own reviews of Boeing’s software changes and the need for additional pilot training.

The FAA did not allow reporters to attend or watch the meeting, and it kept them away from international aviation officials who attended the all-day session at a gated FAA office in Fort Worth, Texas.

It is unclear whether the event will do much to convince travelers that the Max is safe.

Barclays said that its survey this month of 1,765 travelers in North America and Europe found that nearly half plan to avoid flying on the Max for a year or longer. About half said they would pick a non-Max flight if given the choice.

Airlines are making plans for a campaign to reassure nervous customers. They know it won’t be easy.

American Airlines CEO Doug Parker told NBC that because of all the news coverage of the crashes and their aftermath, no amount of marketing will sway worried passengers.

“There may be some period of time” before customers are comfortable flying on the plane, Parker said, “but we will work through that.” He suggested that if passengers see U.S. pilots getting on board, they will follow.

United Airlines CEO Oscar Munoz said this week that he will be on the carrier’s next Max flight. He added, however, that United would let passengers who don’t want to fly on the plane rebook without the customary ticket-change fee.

The Flight Safety Foundation, a nonprofit group based in the Washington suburbs, is urging regulators to coordinate recertification of the Max. The group’s CEO, Hassan Shahidi, said that would lift public confidence and be less disruptive than a fragmented, country-by-country return of the plane.