Smith will face up to 15 years in prison when sentenced April 16. But his attorney, William Brennan, said the recommended sentencing is 12 to 18 months.
Smith, 26, called airport police Sept. 6 and said that Christopher Shell, 29, who was traveling on a flight bound for Texas, had liquid explosives on board. The plane, with 69 passengers and five crew members, was over Harrisburg when it was ordered to return to Philadelphia. Shell was led off the plane in handcuffs.
According to court documents, Smith called in the threat from a pay phone because Shell, who had dated the same woman, had posted a naked picture of the 19-year-old woman on Facebook.
In the "20/20" segment, Shell, who also was interviewed, said that he posted the naked photo after the woman ended their relationship.
"The Facebook photo was there to say, 'Hey. See you later. I had my fun. Bye,' " Shell said in the interview.
Smith claims that he called in the threat as an act of chivalry to avenge the woman's honor, although he said in the interview that he now knows his actions were "completely moronic."
"It all happened so fast," Smith said in the interview. "Make a phone call in the morning, and 6 o'clock at night I'm sitting in a cell."
In the "20/20" piece, both men said that they were no longer romantically involved with the woman. However, the woman appeared in court today to support Smith at his hearing. Brennan said that the two are now just friends.
Outside the courtroom Monday, Smith declined to answer questions. When asked why he granted "20/20" an interview, he said: "I wanted to make sure people knew I was sorry for what happened."
Smith wept several times during the hearing. He said that he lost his job at a Port Richmond pizza shop as a result of the incident, but now works at another restaurant. He admitted to the judge that he had smoked marijuana two days before the hearing, but said that he would stop.
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