The woman, identified only as Airman 1, told the jury hearing the court-martial of Tech. Sgt. Christopher Smith in Texas she had looked up to Smith as a father figure and was very uncomfortable during the incident, the San Antonio News-Express reported.
"All I could do was look down at my hands because I was just trying to figure out how to get out of that situation," she said.
Smith is facing charges of making sexual advances toward a trainee, seeking to develop an intimate relationship with her and wrongfully having a social relationship with another trainee, as well as one count of obstruction of justice.
Prosecutors allege that in spring 2011, Smith drove the two trainees to a house off Joint Base San Antonio-Lackland, where they met up with fellow instructor, Master Sgt. Jamey Crawford.
Smith allegedly then led Airman 1 to a bedroom where he made sexual advances toward her, while Crawford and the other trainee had sex in another room.
The 19-year-old trainee was the last of three witnesses called by prosecutors rested their case. Smith's attorney did not call any witnesses.
The case, which is being heard by a jury of seven commissioned officers, was heading toward closing arguments Wednesday afternoon, the newspaper said.
If found guilty, Smith could be sentenced to 12 months in prison, a bad-conduct discharge, forfeiture of two-thirds of his pay for one year and reduction to pay grade E-1.
Crawford is charged with having a sexual relationship with a basic trainee, giving her alcohol and committing adultery. His court-martial is scheduled for Sept. 5.
Similar sexual intimidation accusations have been leveled against 15 basic training instructors at the base, the newspaper said.