But one recent parolee in San Diego, with a reported rap sheet 22 pages thick, didn't let little things like rules and regulations stop him from boarding a place -- even though he didn't have a ticket.
In fact, the man, whose identity has not been released boarded United Airlines flight 6323 at San Diego International Airport without a ticket Tuesday morning after getting onto the tarmac through a fire door, according to police.
The plane's 11:15 a.m. departure was delayed out of Lindbergh Field to LAX due to a Transportation Security Administration investigation, according to San Diego Harbor Police.
A witness aboard the plane told Fox 5 San Diego that the man wandered out of a fire door onto the tarmac, dropped off a bag, boarded the flight, and took a seat on the flight.
The alarm quickly sounded, but the man handed his duffle bag to a flight attendant, saying he urgently needed to use the bathroom, NBC San Diego reported.
"When he went through the door, it set off the alarm. It was caught on camera," San Diego Harbor Police Lt. James Jordan told NBC San Diego.
The flight attendant quickly realized there were too many people on the plane and identified the extra passenger, who was easy to spot, according to fellow passenger Nicholas Blasgen, who described the accused as looking disheveled and suspicious.
"Within a minute of this happening we had cops and K-9 units out there," Blasgen told Fox 5 San Diego.
After that, the passengers were told to get off the plane while dogs sniffed their bags. Then they were all forced to go through security a second time before taking off. But while they had to answer security questions to get back on board, Blasgen had some questions of his own.
"How could this happen? " Blasgen rhetorically asked NBC San Diego. "In this day and age when I have to take my shoes off to get on a plane, this guy bypasses everything. What if he had a bomb?"
Officials did not release the identity of the suspect, but said he was a parolee, who was released from jail Monday and wanted to travel to Alaska to meet up with family.
According to police, the suspect was mentally ill with a criminal record 22 pages deep, including convictions for theft and prostitution.
That rap sheet may get longer. The unticketed passenger is back in jail and being held for two counts of trespassing.
Meanwhile, the flight departed just before 1 p.m., but Blasgen called the whole thing "an ordeal."