Ali Reza Shahsavari, 30, of Indialantic, Fla., rambled about meeting President Obama and vandalized the airplane's restroom on a Southwest Airlines flight from Los Angeles to Orlando, Fla., in October, authorities said.
The flight made an emergency landing in Amarillo, Texas, after he screamed, a passenger said, "You're all going to hell. Allahu Akbar," which translates from Arabic as "God is great".
He was arrested and later indicted by a Lubbock grand jury, and spent a month in a low-security prison in Austin, but in court in Amarillo Monday, U.S. District Judge Mary Lou Robinson accepted his plea of not guilty by reason of insanity.
Shahsavari explained in court he was prescribed the medication Abilify in 2005, used to treat schizophrenia, and had not slept or taken his medication before the flight. He said that, while he did not dispute the indictment's allegation, he did not remember his actions aboard the plane.
He will undergo a final evaluation in Fort Worth within 40 days, court records state.
"I'm just really sorry. I just want to go home to Florida," Shahsavari said in court, the Amarillo Globe-News reported.