Boeing Co. directors plan to meet with top executives from some of their largest airline customers, who are growing increasingly frustrated about the planemaker’s crisis tearing into their business.

Dave Calhoun, Boeing’s chief executive officer, will not participate in the gatherings set to begin next week, said people familiar with the matter. Larry Kellner, the chairman of Boeing’s board, is spearheading the unusual listening tour, and will be joined by two to three other directors for each session, although the cast of participants will vary, said the people, who asked not to be identified as the plans are confidential.

For Kellner and other board members, the initiative will provide unfiltered feedback from some of the largest airlines in the world, as Boeing navigates another crisis centered on its most important product, the 737 Max jetliner. Calhoun is supportive of the sessions, a Boeing official said. 

The plans underscore the growing customer frustration with Calhoun and Stan Deal, the head of Boeing’s commercial aircraft business, as a crisis centering on the planemaker’s manufacturing quality and safety shows no signs of receding nearly three months after a fuselage panel blew out of an airborne 737 Max. 

A sweeping audit of Boeing and its suppliers by the U.S. Federal Aviation Administration raised concerns about the company’s safety culture, the agency’s top official said March 19.  

Read More: Boeing Sees Massive Cash Drain as 737 Max Episode Takes Toll

Kellner, a former airline CEO, initiated the customer outreach after several top U.S. airline chiefs discussed meeting as a group with Boeing directors during a recent session of the Airlines for America trade group, the people said. The Wall Street Journal earlier reported that the airline leaders had approached the board.

Planning discussions are still underway, and a meeting schedule has not been finalized, the people said. The sessions are expected to include the chiefs of the major U.S. carriers in addition to key international airlines, such as Ryanair Holdings Plc’s outspoken CEO Michael O’Leary.

Boeing’s largest U.S. customers include American Airlines Group Inc., United Airlines Holdings Inc., Delta Air Lines Inc., Southwest Airlines Co. and Alaska Air Group Inc.

“We have ongoing, frequent communication with Boeing, which is not new and will continue,” Southwest said in a statement.The CEOs of multiple prominent airlines have aired frustration with the state of Boeing’s operations since the January accident. 

Michael O’Leary, the outspoken CEO of Ryanair Holdings Plc, on March 20 called on Boeing to get its act together during an airline conference in Brussels. While he voiced confidence in Calhoun and chief financial officer Brian West, the Ryanair leader said “the performance in Seattle has not been acceptable.”

Ryanair won’t take part in the meetings with Boeing directors, the airline said in a statement.

Representatives for Boeing, American, United, Alaska and Airlines for America either had no comment or didn’t immediately respond.