Jaren Yang, the passenger, said no one was injured and noted that he and other passengers were not aware of a disturbance until the pilot announced a security threat 20 minutes before landing.
According to authorities, Anil Uskanil, 25, was a ticketed passenger aboard the flight and had gone through a TSA screening.
"Crazy! Someone tried to break into the cockpit on my flight from LA to Honolulu", the Instagram user wrote.
Mark and Donna Basden were among the first to board the plane and found a laptop in the seat pocket of Mark Basden.
Passenger Lee Lorenzen told CNN affiliate KITV that the flight attendant told the man: "You're not coming in here" and used the cart to block his path.
Basden returned it to the man when he came out.
The Los Angeles Police Department said at LAX, the man was involved in a separate security incident and was detained but subsequently released, Hawaii News Now reports. That's when Uskanil, now apparently wearing a towel or blanket over his head and with his laptop in his hand, was trying to get into the first-class cabin.
The flight attendant ran down the aisle with her serving cart and blocked the doorway separating first class from the rest of the plane.
A passenger aboard the flight posted a video of agents in Federal Bureau of Investigation shirts taking the suspect off the plane in handcuffs.More news: Over 60 electoral 'violations' in run-up to Iran vote: judiciary
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The media outlet reports police said the suspect went through a door from a concourse that led onto an airfield ramp. They say he was spotted by a contractor and detained until police officers arrived.
Police say Uskanil had been drinking but didn't meet the criteria for public drunkenness. He was arrested on suspicion of misdemeanour trespassing and given a date to appear in court.
After landing in Honolulu on a flight from Los Angeles, passengers described a midair disruption involving an unruly man whose attempts to get to the front of the jetliner prompted flight attendants and passengers to subdue him. and fighter jets to escort the plane.
Lorenzen and his wife Penny Lorenzen, of Orange County, California, were sitting in first class and saw a really serious look on the flight attendants face. "He was pushing against the cart and a bunch of guys grabbed him".
Flight attendants, an off-duty Los Angeles police officer and other passengers were able to stop the man and secure him in a seat.
The official says the man had "tried to breach the cockpit door" and was taken into custody by federal agents when the plane landed.
Federal agents escort the man off the plane.
American Airlines aircraft sit on the tarmac at LaGuardia airport in NY.