Passengers recall the fear that gripped the dissident journalist as their flight was diverted.

The tray tables were being raised and the seat backs returned to the upright position as passengers on Ryanair Flight 4978 prepared for the scheduled landing in the Lithuanian capital, Vilnius. Then, suddenly, the plane made an abrupt U-turn.

There was no explanation given.

It would be roughly 15 minutes before the pilot came over the intercom and announced that the plane would be diverting to Minsk, the capital of Belarus, according to those on board.

For many passengers, it seemed, at first, it was most likely just one of those unexpected delays that can be part of airline travel — perhaps a technical problem, some speculated.

For one passenger, however, the situation was clear. And frightening.

Roman Protasevich, a prominent Belarusian opposition journalist who had been living in exile since 2019, started to panic.

“He panicked because we were about to land in Minsk,” Marius Rutkauskas, who was sitting one row ahead of Mr. Protasevich, told the Lithuanian broadcaster LRT upon arrival in Vilnius. “He said: ‘I know that death penalty awaits me in Belarus.’”

Once in Belarus, Mr. Protasevich’s worries appeared more real than ever. The plane was surrounded by Soviet-looking officials in green uniforms, along with dogs, fire crews and technical workers from the airport.

Saulius Danauskas, a passenger who spoke to Delfi, a news website, after arriving safely in Vilnius, said it quickly became apparent to him that the notion of a bomb threat was all a ruse.

“When we landed people were standing around the plane doing nothing, looking pleased with themselves,” Mr. Danauskas said. “They didn’t let us out for half an hour,” he added. “If there was a bomb on the plane, why would they not let us out?”

Passengers were eventually told to descend in groups of five with their luggage, which was thoroughly checked by security officials.

Mr. Protasevich’s luggage was checked twice, passengers recalled. Then a security officer escorted him to the terminal, where he was arrested.

Most of the rest of the passengers were kept standing in a dark corridor for three hours. Some had to stand with their children. Guarded by security officials, they had no access to food, water or a toilet.

In retrospect, passengers noted how weird it all was.

Mantas, a passenger on the plane, told a Lithuanian news website that the pilot was “visibly nervous” during the landing in Minsk.

Alyona Alymova, one of the passengers, wrote about the experience in a Facebook post, noting that for much of the time there was only “light anxiety.”

“There was no clear understanding of what was going on,” she wrote.

Some passengers learned about the bomb threat only hours later, when they could connect to the internet.

In an Instagram post, one passenger said that they were “treated as prisoners in Minsk.” Hours later, they were allowed in an airport lounge area with a small cafeteria.

“I want to see who will be responsible for this chaos,” she said.