Deutsche Lufthansa AG executives sought to calm customer nerves frayed by a dozen pilot strikes while cautioning that walkouts may continue, as cabin-crew employees offered to assist in ending the dispute.

In a letter dated March 20 that was sent to the airline’s customers, senior managers apologized for disruption from strikes, while vowing they “cannot and will not make any compromises that endanger our future viability.” Pilots are asking to keep conditions under an early-retirement program, and have just emerged from the longest strike in the carrier’s history.

With both sides still at loggerheads, the UFO cabin-crew union took the unusual step of proposing a conciliatory role under the stewardship of an external mediator, saying all Lufthansa employees are ultimately bearing the brunt of the walkouts. The dispute cost Lufthansa 220 million euros ($240 million) in operating profit in 2014.

“It can’t go on like this,” UFO wrote in a statement today after 220,000 customers were affected by last week’s strike. The company and pilots are “holding all employees hostage” in their conflict over pensions, which ought to be solved through mediation including representatives of cabin and ground staff, UFO said.

Lufthansa’s management board is scheduled to meet on Tuesday. The conflict has grounded more than 9,300 flights in a year, as the airline tries to reduce pension costs. Those expenses contributed to the suspension of the dividend for last year as the carrier tries to preserve cash. Lufthansa is trying to reduce overheads as it faces increasing competition from low- cost airlines and Persian Gulf rivals.

‘Last Resort’

Pilots have already gone on strike for six days in 2015. Last week’s walkout saw more than 1,600 flights scrapped from Wednesday through Saturday.

UFO suggested bundling a number of labor issues in an arbitration process. Lufthansa has said it sees arbitration as a last resort if formal negotiations fail and there have been no talks yet on some of the topics.

Still, the company has said it may be willing to agree to mediation on some issues if they exclude issues of strategy such as its decision to operate long-haul flights with its Eurowings budget arm.

The Vereinigung Cockpit pilots union has said it won’t accept younger pilots having to agree to early retirement benefits that are “noticeably worse” than those paid to longer-serving ones.

This article was written by Richard Weiss from Bloomberg and was legally licensed through the NewsCred publisher network.

Photo Credit: Pilots walk past a flight schedule board announcing cancelled flights of German airline Lufthansa at Munich's airport. Michaela Rehle / Reuters