The Air Force expects to lose more remotely piloted aircraft pilots to attrition than it trains this fiscal year, Air Combat Command spokesman Benjamin Newell said on Friday.

The active-duty Air Force already has a shortfall of RPA pilots, in part because more RPA pilots are joining Air National Guard units, an Air Combat Command official told reporters on Thursday.

On Friday, Newell told reporters that the loss of active-duty RPA pilots to the Air National Guard is not the main reason why the Air Force projects that it will train fewer RPA pilots than it loses in fiscal 2015.

"We are losing them through a combination of factors," Newell said in an email to Air Force Times and other media outlets. He did not elaborate what those factors are.

"Factors leading to a decrease in the number of pilots available to fulfill surge level mission requirements are manifold, but we're in the planning and coordination stage at the moment," Newell said in a follow-up email to Air Force Times. "We're not able to discuss specific measures, because we don't yet know which ones we'll use."

The head of Air Combat Command recently wrote a memo to Chief of Staff Gen. Mark Welsh explaining the RPA community was coming under increasing stress to fly all of the combat air patrols being asked of pilots, as first reported by The Daily Beast.

"We are above our program of record," Col. Ray Alves, of Air Combat Command, told reporters on Thursday. "We're actually at surge capacity right now – and surge, by definition, we cannot maintain forever. So we need to start looking at … how do we ensure that the enterprise is correctly manned to continue to meet the levels of demand that the combatant commanders are putting upon us."