Paris Hilton's youngest brother, Conrad, agreed to plead guilty to assaulting flight attendants on a trip from London to Los Angeles last year during which authorities say he called other passengers "peasants" and threatened to kill crew members.

Hilton, 20, signed the agreement Tuesday and is set to appear in court Thursday, but will officially plead guilty to the misdemeanor later, said the U.S. attorney's office in Los Angeles.

The offense carries a maximum sentence of six months in jail, a year of probation and a $5,000 fine, but under the deal prosecutors said they would ask a judge to give Hilton only probation.

Hilton's attorney, Robert Shapiro, did not immediately reply to an after-hours phone message seeking comment. But Shapiro said previously that Hilton's behavior may have been "the effects of a sleeping pill" or some similar circumstance.

According to an FBI affidavit, Hilton acknowledged calling other passengers "peasants" and said he had would have killed one flight attendant if another passenger hadn't calmed him down during the 10-hour July 31 flight.

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Hilton ignored instructions to keep his seat belt fastened and began pacing the aisle as the aircraft ascended, the document said.

When told to sit, he launched a series of tirades that had some of the children aboard the plane in tears. He threatened to kill several flight attendants and a co-pilot, and threatened to get them fired, the affidavit said.

"I could get you all fired in five minutes. I know your boss," Hilton said in one of the document's few quotes that didn't include an expletive.

Hilton said he was angry over the breakup with a girlfriend and wanted to smoke marijuana. At one point, he went to a lower deck restroom and the odor of marijuana wafted out, the affidavit said.

Hilton threw a punch inches from another flight attendant's head that struck the bulkhead, the affidavit said. Although the attendant said he felt threatened, he said, "I don't believe he intentionally wanted to hurt me."

WATCH: Conrad Hilton to face consequences

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