An FBI affidavit states that passengers on the June 21 Allegiant Air flight saw Martin exposing his genitals and twice joined Stroble in oral sex and other acts despite warnings from flight attendants.
One of the passengers complained to an attendant that "this is not the sex education I wanted to give my teenage sons," according to the criminal complaint.
Martin and Stroble were asked to stop by an attendant and did so during the drink and snack service, but later repeated the sex acts before landing, the affidavit states.
The original charge carried a maximum sentence of up to 90 days in jail and a $US500 fine, according to the complaint.