Xue Vang had long known that his job deicing planes, loading bags and chocking wheels at the Missoula airport was dangerous, especially in the Montana winter, when blinding snow and rain obscure the spinning engines that can suck in a human body.

But this past winter, the conditions at Unifi, which services planes for United and Delta, became intolerable. Because of the pandemic, understaffing was so bad that Vang was simultaneously handling two or three planes on the “ramp,” or tarmac, while making sure new trainees didn’t get inhaled into the engines.

One day, Vang’s colleague Jared Bonney was complaining that he’d been promised a raise for years that never materialized. “I was like, ‘Join the club,’” Vang recalls. Bonney’s pay was capped at $10.40 an hour; Vang, whose job was more senior, was capped at $11.50. Single adults would need to make $14.13 an hour to support themselves in Missoula, according to MIT’s living-wage calculator.

Other Unifi workers started sharing complaints about low pay, lousy conditions and broken promises of raises, even though their jobs required specialized training…