While some passengers disrupt flights with drunken rages, verbally abusive outbursts, or other violent actions, others are quieter in their approach. Like a United Airlines passenger who was arrested after allegedly making up a bomb threat and reporting it to the flight crew.

According to the FBI, a 20-year-old man on a flight from San Diego to Denver on Monday claimed he’d found a note in the bathroom that said there was a bomb on board, and warned the crew not to try to land the plane.

He then gave the note to the flight crew, the agency says, which notified police and the FBI. Once the plane landed, it taxied to an isolated runway to evacuate passengers onto buses. Police swept the plane with bomb-sniffing dogs, but no explosives were discovered.

Agents started to get a whiff of something suspicious when they asked the passenger to write an account of what happened, and noticed that his handwriting looked a lot like the handwriting in the note he’d supposedly “found” in the bathroom.

Instead, authorities allege, he found a piece of paper jammed in his seat, wrote the fake threat on it, then hid it in the toilet seat cover dispenser in the bathroom so he could point it out to a flight attendant like he’d never seen it before.

He’s now facing federal charges of maliciously conveying false information, and could be sentenced to up to 10 years in prison and a fine of up to $250,000.

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