Staff Sgt. Emily Allen wiped away tears after Col. Donald Eller Jr. accepted her admission that she had a tryst with the trainee on Independence Day weekend in 2011.
Allen pleaded to that charge and three other specifications that included an attempted sexual relationship with another technical school trainee, as well as improper social relationships with two women in the Air Force.
“I have no excuses for my choices, and I'm aware of everything that I've done,” she said.
A 10-year Air Force veteran, Allen is the only woman among 33 boot camp instructors who have been charged with illicit contact with 63 recruits and technical school trainees.
Eller will reconvene court Thursday to decide punishment in the case.
She could receive 12 months in jail, a bad-conduct discharge, forfeiture of two-thirds' pay for a year and reduction to the Air Force's lowest rank.
It's rare for female training instructors to be tried for having consensual sex or being involved in improper relationships. The last case at Lackland was in 2001.