But employees were often blindsided by the labor setup once they were inside, according to the current and former Ryanair pilots and crew members.

Thousands of new Ryanair pilots went through the same process as Mr. Van Boekel. Some were required to form limited liability companies in several countries with pilots they didn’t know.

As contractors, they didn’t receive standard benefits for pensions or health insurance. Pilots and flight attendants on Ryanair’s Irish contracts weren’t always protected by labor laws in the countries where they worked. Ryanair said its contracts complied with labor laws in Ireland and the European Union.

Pay has been another concern. Self-employed pilots and aircrew members are paid only for hours flown, but not for time spent preparing for a flight, or when they are delayed or canceled. Minimum monthly work hours were promised though not guaranteed.

Contractor pilots paid their own transportation and costly hotel bills when assigned to fly from different airports. Like flight crews, they said they shelled out for uniforms, food and even drinking water on flights. Ryanair said that staff members received allowances to defray the costs of uniforms and other expenses. The company’s go-to employment agencies required job seekers to pay for qualification training, starting at around €2,500 for flight attendants and about €30,000 for pilots.

When tax authorities raided Ryanair’s German sites as part of their investigation into alleged tax evasion by Brookfield Aviation, they also questioned pilots who had signed contracts with Brookfield. That set off a mild panic among Ryanair pilots elsewhere in Europe with the same contracts.

Pilots, in interviews, said they felt discouraged from raising workplace concerns, which could lead to being called into Dublin for tense meetings with managers. Others recounted being pressured to limit their fuel consumption and fearful of being reprimanded if they complained of fatigue. Flight attendants reported coming to work ill and scrambling to fulfill sales quotas on flights for lottery cards, perfumes and other items to avoid rebuke by managers. Ryanair said it did not limit fuel consumption and that its aircraft take off with fuel exceeding E.U. safety guidelines. The company disputed reprimanding staff for complaining of fatigue or illness.