The US Air Force is looking into the possibility of replacing the Martin-Baker ejection seat on the F-35. is reporting that the United Technologies ACES 5 model is under consideration.

Air Force Lt. Gen. Arnold Bunch, the service’s top uniformed acquisition official, confirmed the service’s interest in the ACES 5 design.

“We believe it is prudent to look at what it would take to qualify the ACES 5 seat as a potential risk mitigation step if additional things happen as we go through the testing of the Martin-Baker seat,” Bunch said Friday. “We believe it’s prudent to determine what it would cost, how much [impact on] the schedule, what the timeline would be, if something else happened and we wanted to go a different way.”

Ejection seat issues for the F-35 surfaced last year. Authorities discovered that the ejection seat was not rated for lighter pilots and could cause them injury. Lightweight pilots had a 1 in 50,000 chance of hurting their neck from an ejection, compared with pilots weighing 136 pounds (62 kg) to 165 pounds (75 kg), who had a risk of 1 in 200,000 of a neck injury.