Costs for Boeing Start to Pile Up as 737 Max Remains Grounded

And when the Max is approved to fly again, it remains unclear whether passengers will feel comfortable on the planes. In the days after the crash of Ethiopian Airlines Flight 302 in March, before the Max was grounded, the travel booking website added a filter that allowed customers to filter by plane type.

Yet for all the uncertainty facing Boeing today, analysts believe there is little long-term risk to the company. Boeing and its European rival Airbus are the only significant manufacturers of commercial aircraft. And the 737 Max, for all its problems, remains one of two midsize fuel-efficient passenger jets on the market, along with the Airbus A320neo.

“Boeing’s best protection is that this is a supply-constrained industry,” Mr. Aboulafia said. “There are only two modern airplanes that offer fuel savings. The risk of defection is minimal because of that.”

Nor is there much risk that airlines that have already placed orders with Boeing will walk away, analysts said. With Airbus also backlogged, airlines looking for new planes have no real alternatives.

“Boeing’s ability to modify the aircraft effectively, the duopoly structure of the aircraft market, the large installed base of 737s, and Boeing’s deep and long-term relationships with its customers mean that demand for the Max will not change dramatically,” Mr. Seifman wrote.

Even if Boeing weathers the immediate financial storm, it faces other unknowns. The families of passengers and crew members killed in the Ethiopian Airlines crash and the crash of Lion Air Flight 610 in October have hired lawyers to pursue legal claims against the company.

The Transportation Department’s inspector general and the Justice Department are investigating the design, manufacturing and certification of the Max. And it may be months or even years before Boeing wins back the public’s confidence.

“The general flying public seems to be asking more questions about the airplane than they have with prior fleet groundings,” Mr. Poponak, the Goldman Sachs analyst, wrote in a recent note. “We see a risk that lasts in the order book moving forward over the next few years.”