LOS ANGELES (CBSLA) – A 20-year-old Irvine man has been federally charged with attacking a flight attendant aboard an American Airlines flight from New York to Orange County last week, forcing the plane to be diverted to Denver.

The passenger suspected of alleged assault of a female flight attendant on AA Flight 976 from JFK to John Wayne Airport. (source: Mackenzie Rose)

The U.S. Attorney’s Office reported Monday that Brian Hsu has been charged with interference with a flight crew and assault within the special aircraft jurisdiction of the U.S.

During a brief court appearance in Santa Ana on Monday afternoon, U.S. District Judge Autumn Spaeth set Hsu’s bond at $10,000. He was expected to post that and be released from custody.

Spaeth also restricted his travel to Rhode Island for unspecified medical care, Southern California and Denver. Hsu will need permission to travel elsewhere, but Hsu’s public defender, Andrea Jacobs, indicated that he wants to return to school in New York in the spring.

The attack occurred on the evening of Oct. 27 aboard American Airlines Flight 976 from John F. Kennedy Airport to John Wayne Airport, prompting the fight to be diverted to Denver International Airport.

According to an FBI affidavit in the case, Hsu was returning home after undergoing brain surgery when the purported attack occurred.

The defendant’s mother, Julia Yu, was on the plane with him at the time and is a witness in the case. She declined to comment after Monday’s hearing.

Four witnesses told the FBI that the flight attendant told Hsu to stay away from the plane’s bathroom, prompting him to punch her in the face “with sufficient force to cause her to hit the lavatory door,” the FBI alleged in an affidavit.

Another witness said it appeared the defendant punched her in a way that was “practiced or trained,” according to the document. Another witness “recalled the victim stating, “I have a fractured nose’ after the strike.”

According to the affidavit, the flight attendant told an investigator said she was in the “mid-galley section of the airplane when she felt something strike her in the head.” When she turned to see what had struck her she saw the defendant and she asked him if he was OK, the investigator wrote in the document.

Hsu did not apologize and said he needed to use the bathroom, the victim told the investigator.  She told Hsu it was occupied and that because the “fasten seatbelt” sign was on, he needed to go back to his seat, according to the document.

Hsu made a motion to stretch again, but instead slammed his elbow on her head, the victim told the FBI. That prompted her to take a “defensive posture with her arms out in front of her and her hands up.”

Hsu backed off, but “then charged at her, flailing his arms,” the victim told the investigator. Another flight attendant then rushed over to intervene and Hsu backed off again, but when he charged her again he “struck her in the face with the closed fist of his right hand,” the victim said, according to the document.

The victim said she was “stunned and walked into the first-class cabin where she met up with the lead flight attendant and reported the assault,” the FBI said.

An announcement was made for two men on the flight to help restrain Hsu.

Another flight attendant told Hsu to go sit down, which he did eventually, an FBI investigator stated in the document. Hsu was then restrained with duct tape and “plastic bonds,” according to the affidavit.

“Many witnesses commented on Hsu’s odd behavior before and after the incident,” the FBI said.

The plane then landed at Denver International Airport a little after 6:30 p.m. Mountain time Wednesday. The flight attendant was treated at a Denver hospital for broken bones to her face, the Association of Professional Flight Attendants union said.

American Airlines has told CBS News that they do not believe the attack was mask-related.

“I understand that he actually punched her twice,” Mackenzie Rose, a passenger on the flight, told CBSLA last week. “I did see her walk back down the aisle afterward. She had blood splattered on the outside of her mask.”

American Airlines issued a statement at the time saying, “Acts of violence against our team members are not tolerated by American Airlines.”

The airline announced that Hsu would no longer be permitted to fly on AA.

Hsu is next expected in federal court in Denver on Nov. 15.