Paris Hilton’s younger brother Conrad will plead guilty to an assault charge relating to a disturbance on a transatlantic flight last summer.

Thom Mrozek, a spokesman for the U.S. Attorney’s Office, said that the 20 year old socialite will appear in a federal courtroom on Thursday to be arraigned on a misdemeanour assault charge. If found guilty, he apparently faces up to six months imprisonment, in addition to a further year of supervised release and further fines.

Conrad Hilton
A youthful Conrad Hilton (L) back in 2008 at a red carpet call

Court documents obtained by the L.A. Times reveal that Hilton signed the plea agreement back on February 19th. As part of the plea, he cannot argue the facts of the case, must attend all court appearances and cannot commit any other crimes. He is not expected to actually enter any plea when he appears in court tomorrow.

More: Paris Hilton buys New York home

The charges relate to an incident dating back to last summer, and Hilton originally surrendered to the FBI early in February after being charged with assaulting the flight attendants and crew to the point that it was impairing them from carrying out their duties.

The hotel chain heir was a passenger on British Airways Flight 269 on July 31st last year from London to Los Angeles when he began repeatedly entering the bathroom and smoked tobacco and marijuana, according to reports at the time from TMZ.

Hilton apparently went into meltdown when challenged by flight attendants, physically threatening them and shouting things like “I am going to f***ing kill you!” and “I will f***ing own anyone on this flight - they are f***ing peasants”. The episode left fellow travellers, including several small children, frightened and distressed.

When Hilton eventually fell asleep, flight attendants restrained him and handcuffed him to his seat upon the orders of the captain in preparation for the plane’s descent.

At the time of his arrest, Hilton had argued that a sleeping pill that he had taken before the flight originally departed from London had impaired his behaviour and that he had little recollection of the incident.

More: Paris Hilton turns down car gift from fan