She had pleaded no contest to willfully and unlawfully entering the city as a stowaway on an aircraft, a misdemeanor, and was sentenced to 24 months' probation and ordered to keep away from LAX.
Hartman had recently left mental treatment that she had been ordered to attend.
She said homelessness drove her to take "desperate measures," and that she feels safer being in airports than in the streets.
On Monday she had made at least three attempts to get to a plane before she finally went past a screener who was busy checking a family's documents at Mineta San Jose International Airport, according to law enforcement officials. They would speak only on condition of anonymity because the security breach is being investigated.
She then went through the electronic screening process before entering an airport terminal.
Her boarding status was discovered once Southwest Airlines Flight 3785 landed in Los Angeles, the officials said.
Her breach of security caused federal officials and the airline to launch investigations. It also prompted criticism of San Jose's airport in light of the trespassing of a teenage boy who stowed away in the wheel well of a Hawaiian Airlines flight and survived the arduous journey to Maui.
In February, Hartman was sentenced to 18 months' probation in San Mateo County after being arrested for attempting to board three Hawaii-bound flights at the San Francisco International Airport on three separate days. In November 2010, Hartman made it as far as the airport baggage claim on the Hawaiian island of Kauai before being arrested, the San Francisco Chronicle said.
Hartman told authorities in the past that wanted to fly somewhere warm because she had cancer, said Steve Wagstaffe, district attorney for San Mateo County. Hartman had cancer but has been in remission for several years, the San Francisco Chronicle reported.
Authorities placed Hartman in treatment for mental disorders in May but said she stopped attending last month. Wagstaffe said he had no plans to take any additional measures against her.