Sen. Joni Ernst of Iowa is urging the Air Force to consider a "buddy system" for trainees at Joint Base San Antonio in Texas -- having them travel in pairs as a way to reduce the risk of sexual assault.

Ernst, who retired from the National Guard after 23 years and served in combat, said she was surprised that the Air Force is "the only service that did not require such a system for all of its students in training status," she said in a letter addressed to Air Force Brig. Gen. Heather L. Pringle, commander of the 502nd Air Base Wing.

"Specifically, the Air Force does not require students in training status on JBSA-Ft. Sam Houston or JBSA-Randolph to travel in a buddy pair," the Iowa Republican said. "This is disappointing, as the buddy pair system not only can reduce vulnerabilities for sexual assault, but also helps young service members make better decisions.

"When I deployed in support of Operation Iraqi Freedom as a captain, all service members on our base were required to travel in pairs, including myself," Ernst said Jan. 25.

Capt. José Davis, spokesman for Air Education and Training Command, the service's leading command for basic trainees, on Friday told Military.com it is "aware of Senator Ernst's letter."

"We are in coordination with 2nd Air Force officials, the organization responsible for overseeing basic military and non-flying technical training for the Air Force, to evaluate what we have in place equivalent or not to the buddy pair system expressed in the letter," Davis said in an email statement.

"We take great measures to ensure a wingmanship culture in our basic military training. Today's trainees are assigned a wingman on day zero of training. If one trainee needs to go anywhere, his or her wingman is required to accompany the trainee.

"Additionally, each Airman carries a 'wingman card' on their person at all times. On the card, it has the name of their wingman as well as emergency phone numbers to the trainee/student hotline and their sexual assault response coordinator. Safety of our Airmen is always a top priority," Davis said.

The Army, Navy and Marine Corps have mentorship programs that remind recruits and active-duty service members to watch each other's backs when in off-duty situations and when deployed.

Ernst's letter stemmed from her visit to Fort Sam Houston in November, which she said focused "on investigating military sexual assault."

The senator's letter did not specifically mention Lackland Air Force Base, part of Joint Base San Antonio, where more than 30 female trainees were sexually assaulted by male drill instructors dating back to 2009. By 2014, at least 28 Military Training Instructors, or MTIs, had been charged or convicted of sexual assault and other crimes linked to the scandal, according to Air Force Times.

Retired Air Force Col. Don Christensen, a former chief prosecutor in the Air Force, said Ernst's efforts speak to a larger problem.

"If our recruits have to travel in pairs to avoid being sexually assaulted, we have a major problem," Christensen, now the president of the advocacy group Protect Our Defenders, said in a statement Friday.

"A service member should be able to walk on a military base by themselves without the fear of being sexually assaulted. That should be the standard.

"It's clear that Senator Ernst sees the current system is failing our troops. We call on her to join with Senator Kirsten Gillibrand and many of her Republican colleagues in supporting fundamental reform to fix the broken military justice system," he said.

Both Ernst and Gillibrand, a Democrat from New York, have co-sponsored bills in Congress to combat sexual assault in the military.

"As we continue to see sexual assault plague institutions around the country, it is my hope that the military will continue to take concrete steps to improve and become a leading example for how to effectively curb this problem," Ernst said in her letter to Pringle.

"Therefore, I request that you consider making a buddy pair system mandatory for all Air Force personnel in a training status on Joint Base San Antonio."

-- Oriana Pawlyk can be reached at oriana.pawlyk@military.com. Follow her on Twitter at @Oriana0214.