WASHINGTON — A machinists strike. Another safety problem involving its troubled top-selling airliner. A plunging stock price.

This year was already a dispiriting one for Boeing, the American aviation giant. But when one of the company’s 737 jets crash-landed in South Korea on Sunday, killing all but two of the 181 people on board, it brought to a close an especially unfortunate year for Boeing.

The cause of the crash remains under investigation, and aviation experts were quick to distinguish Sunday’s incident from the company’s earlier safety problems.

Alan Price, a former chief pilot at Delta Air Lines who is now a consultant, said it would be inappropriate to link the incident Sunday to two fatal crashes involving Boeing’s troubled 737 Max jetliner in 2018 and 2019. In January this year, a door plug blew off a 737 Max while it was in flight, raising more questions about the plane.

The Boeing 737-800 that crash-landed in Korea, Price noted, is “a very proven airplane. It’s different from the Max. ... It’s a very safe airplane.”

For decades, Boeing has maintained a role as one of the giants of American manufacturing. But troubles in 2024 have been damaging.

The company’s stock price is down more than 30% in 2024.

Boeing’s reputation for safety was tarnished by the 737 Max crashes, which occurred off the coast of Indonesia and in Ethiopia less than five months apart in 2018 and 2019 and left a combined 346 people dead.

In the five years since then, Boeing has lost more than $23 billion. And it has fallen behind its European rival, Airbus, in selling and delivering new planes.

Last fall, 33,000 Boeing machinists went on strike for seven weeks, crippling the production of the 737 Max, the company’s bestseller, the 777 airliner and 767 cargo plane. Boeing has sought to change its culture. Since January, 70,000 Boeing employees have participated in meetings to discuss ways to improve safety.