Air France Poser and Other Impostors
PHOTO: Phillipe Jernnard, 61, of LaRocelle, France, boarded a US Airways flight, alleging to be an Air France pilot.

An American-hating Frenchman allegedly impersonating an Air France pilot was arrested after a flight attendant and co-pilot found him sitting in the cockpit of a US Airways flight en route to Florida.

Police said Phillipe Jernnard, 61, of LaRocelle, France, was apparently able to gain access to the cockpit and seat himself in the jump seat behind the pilot because he was wearing a white button-down shirt with an Air France logo on it.

A suspicious flight crew contacted police, who arrested Jernnard after finding fake crew credentials, a makeshift ID badge and Air France decals in his luggage.

Jernnard is certainly not the first civilian to pose as a pilot. If he'd been successful, he would have joined the ranks of those who've tricked people into thinking they were somebody else -- celebrity offspring, a decorated military veteran, even a Rockefeller.

There seems to be no single motivating factor that has prompted these people to assume false identities. But, according to Dr. Charles V. Ford, a professor of psychiatry at the University of Alabama at Birmingham, it may stem from the thrill of fooling others.

"It's almost like a hit of cocaine," he said. "This may, in some way, have some of the same qualities as an addiction. [Con artists] do it over and over again to get that kind of a thrill or a hit."

"They have no respect for the laws of society. They think they can do what they want," said Dr. Sara West, a forensic psychiatrist at Northcoast Behavioral Healthcare in Cleveland. "They can be quite charming, and that can be helpful in pulling off a con."

Click through for people who posed as others until they got caught. media: 18788833

Frank Abagnale

Between the ages of 16 and 21, Frank Abagnale managed to successfully pose as an airline pilot, an attorney, a college professor, and a pediatrician. He also made a name for himself cashing $2.5 million in fraudulent checks in the U.S. and abroad.

Apprehended by the French police at 21, Abagnale served five years in prison before joining the ranks of the U.S. federal government to help them catch fraudsters. He has been associated with the FBI for more than 35 years, according to his website.

Abagnale wrote an autobiography, "Catch Me If You Can," about his escapades as a con man. A 2002 film version of the book starred Leonard DiCaprio as the con man himself. A Broadway musical adaptation of the film followed in 2011.

West told ABCNews.com that people who impersonate others have to be organized, smart and flexible.

"These people have to be able to think on the spot. They have to come up with and adapt to changes in their plan very quickly, and to lie," she said. "Dishonesty is at the basis of all of this."

But a con artist's motivation is harder to pinpoint.

"It could be the attention, the thrill seeking behavior, the impulsivity," she said. "That's difficult to say."

Christian Gerhardstreiter

Ever heard of Clark Rockefeller? This German native immigrated to the United States in 1978 on a forged student visa, creating personas for himself that included British baronet, Hollywood producer and Ivy League graduate, before he emerged as a relative of the famed American dynasty.

Dr. Stephen Montgomery, director of Vanderbilt University's forensic psychiatry department, told ABCNews.com that the two common characteristics of con artists are a blend of narcissism and antisocial behavior.

"They are very self-absorbed, and they have an exaggerated sense of their own importance," he said. "They often have these unrealized grandiose fantasies about themselves and that's how they satisfy these fantasies by creating false identities."

Gerhardstreiter's scheme ultimately faced its demise when he was arrested in 2008, and later convicted, for kidnapping his daughter in the wake of limited visitation rights dictated by his 2007 divorce.

But Gerhardstreiter's story didn't stop there. In March 2011, he was charged with the 1985 murder of John Sohus when he allegedly was masquerading in San Marino, Calif., as Chrisopher Chichester. He is currently on trial in Alhambra, Calif.

Matthew Scheidt

Scheidt, 18, was sentenced to a year in jail in November 2012 for impersonating a physician's assistant at a medical center in Kissimmee, Fla.

Scheidt was able to get a badge because he was employed as a clerk as a doctor's office across the street from Osceola Regional Medical Center in Kissimmee. When he went in for his badge, he claimed that he was given the wrong credentials.

While his attorneys blamed hospital administrators for giving the teen a badge without checking his credentials, the prosecution said Scheidt played the part a little too well, and said he dressed in scrubs, wore a stethoscope, and had a knack for the job's technical jargon.

Edith Silva, a hospital human resources employee, testified during the trial that she never verified that he was a physician assistant "because the office was very busy."

Montgomery said that, in some cases, people who impersonate others sometimes may actually believe that they are somebody else or that they actually are that profession.

"They could be psychotic or out of touch with reality," he said.

Scheidt was arrested in Sept. 2011. Four months later, he was arrested for allegedly impersonating a police officer in Miami Beach, Fla.

"He isn't right upstairs," Thomas Scheidt Sr. told "Good Morning America" in September 2011. "He needs some psychiatric help."

David Hampton

Hampton, whose impersonation inspired the play, and later the film, "Six Degrees of Separation," fooled the upper crust of New York society in the 1980s when he posed as the son of actor Sidney Poitier. He was notorious for peddling the Poitier name to get meals on the house, a warm bed to sleep in, and cash to blow.

Hampton was 19 when he was arrested in October 1983. He pled guilty to seven counts of attempted burglary. The judge required him to give $5,000 back to his victims.

The reason Hampton started his scheme? He wanted to get into Studio 54.

"For a person to carry [an impersonation] off, either they have to be incredibly bright to do it, or they want to challenge themselves," West said.

"It would be much harder to impersonate someone who's famous," she said. "That's why people pick famous people."

Hampton died of AIDS-related complications while receiving treatment at Beth Israel Hospital in New York in July 2003. He was 39.

Xavier Alvarez

As a newly elected member of the Three Valleys Water District in Claremont, Calif., Alvarez lied at a 2007 board meeting that he had received a Congressional Medal of Honor as a Marine in 2001 after 25 years of service.

But Alvarez had never served in the military, and was indicted under the Stolen Valor Act, a federal law that made it illegal to claim to have won or wear military honors they did not earn.

He was sentenced to three years probation, a $5,000 fine, and community service.

Alvarez later appealed the decision to the Supreme Court, claiming the First Amendment defends a person's right to lie. He won on appeal, and the Supreme Court declared the act unconstitutional in June 2012.

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