When Air Force leaders sat before the Senate defense appropriations subcommittee Tuesday, they had to answer for the Air Force’s plan to retire some legacy systems in favor of new technology.

“When military leaders tell me that they believe spending money on something is no longer a good idea, I take that very seriously,” the panel’s chair, Sen. Jon Tester (D-Mont.) said in opening remarks at the hearing. “But I also know that new weapons rarely deliver on time and on budget. This subcommittee needs to ask the question of whether the Air Force is rolling the dice.”

Acting Air Force Secretary John Roth, Air Force Chief of Staff Gen. Charles Brown Jr. and Space Force Chief of Space Operations Gen. John Raymond stressed that the divestments outlined in the administration’s budget request are forward-looking.

“Enabling our military advantage in the long term means we need to shift away from legacy platforms and weapons systems that are decreasing in relevance today and will be irrelevant in the future—our aircraft fleet is 30 years old on average, and 44% are beyond their designed service life,” they said in joint prepared opening remarks. “Maintaining our aging weapon systems is costly now and, without change, will mortgage our future.”

Budget hearings continue this week.

Defense Secretary Lloyd Austin and Joint Chiefs Chair Gen. Mark Milley appear before the Senate Armed Services Committee Wednesday morning. The House Armed Services Committee’s readiness panel hears Wednesday afternoon from the vice chiefs of the Army, Navy, Air Force and Space Force, along with the assistant Marine commandant.

Air Force photo by Eric Dietrich