Boeing Co. met with 737 Max operators and lessors in Amsterdam on Tuesday, the first of about six sessions planned around the world as the planemaker lays the groundwork for resuming commercial flights of the aircraft following two deadly crashes.

Executives are using the sessions to discuss how to maintain the jetliners, which were grounded days after a March 10 disaster, said Boeing spokesman Gordon Johndroe. The meetings will also touch on plans to “turn the fleet back on” once regulators clear the Max to fly. Other topics include pilot training, software updates and a public campaign to bolster the jet’s bruised reputation.

“We know that we have a number of areas where we need to improve, including transparency,” Johndroe said in an interview.

Boeing is stepping up customer outreach two days after revealing it had known long before the first 737 Max crash in October that a cockpit alert wasn’t working the way buyers of the jet had been told. The manufacturer is also finalizing an update for software that in both accidents pushed the plane’s nose down until pilots lost control.

The changes will need to be certified by aviation regulators before the jet is cleared to resume commercial flights, and the U.S. Federal Aviation Administration announced a new panel to review the software.

Regulatory Decision

“The decision to return the Max to commercial service rests in the hands of global regulators,” Johndroe said. “In anticipation of that day, we are meeting with our customers in regional conferences to talk through the activities to prepare the fleet and implement the software and training requirements.”

The shares fell 3.9 percent to $357.23 at the close in New York after a downgrade by Barclays Plc, which said that investors were underestimating the fallout from the crashes. Boeing’s drop was the biggest on the Dow Jones Industrial Average, as U.S. markets fell sharply amid fears of a worsening trade war between the U.S. and China.

The FAA is convening a panel of outside experts from the Air Force, the National Aeronautics and Space Administration and a Transportation Department center to review Boeing’s software fixes for the Max.

The panel’s recommendations will “directly inform the FAA’s decision concerning the 737 Max fleet’s safe return to service,” the U.S. regulator said in a statement announcing the Technical Advisory Board. The FAA and Boeing have been working closely on the software update, but the Chicago-based planemaker hasn’t completed its work.

Existing Reviews

The new panel is separate from two other existing reviews created by the FAA. The agency has called for a summit of international regulators later this month to discuss its safety analysis of the aircraft.

The FAA is also conducting a Joint Authorities Technical Review, which consists of eight other countries and the European Aviation Safety Agency, that will examine the Max’s original certification. That work is expected to take three months, with initial meetings held in Seattle last week.

EASA is running its own review of 737 Max’s design, and vowed not to allow flights of Boeing’s best-selling jet until its probe is finished.