WASHINGTON — Top senators on Tuesday told Air Force leaders the service’s plans for modernizing key portions of its fleet could hurt its ability to carry out crucial missions — perhaps for years.

In a hearing, members of the Senate Armed Services air land subcommittee highlighted as worrisome plans to retire half the Air Force’s E-3 Sentry fleet and cut procurement of the EC-37B Compass Call electronic warfare plane and HH-60W Jolly Green II combat rescue helicopter.

The Air Force in March proposed retiring 15 of the service’s 31 E-3s, also known as Airborne Warning and Control System, or AWACS, aircraft, as part of its fiscal 2023 budget. And last month, the service said it planned to start replacing some of the E-3 fleet with Boeing E-7 Wedgetails, currently flown by the Royal Australian Air Force.

But the first of those Wedgetails wouldn’t be delivered until 2027, and subcommittee chairwoman Sen. Tammy Duckworth, D-Ill., said that means it would be several years before significant numbers of Wedgetails would be available to support combatant commanders.

Lt. Gen. David Nahom, the Air Force’s deputy chief of staff for plans and programs, said the dire state of the current AWACS fleet means the service is already facing a considerable gap in its ability to manage battlefields.

The Air Force is struggling to keep even half of the aging AWACS aircraft, some of which were delivered in the 1970s, properly maintained and in the air, Nahom said. And it also is facing “capability issues” Nahom said he could not detail in an unclassified forum.

“The aircraft is exhausted,” said Lt. Gen. Joseph Guastella, deputy chief of staff for operations. “It’s been deployed continuously — much of the Air Force’s fleet is in that condition. It’s not maintainable out there in the field, and it has significant capability gaps.”

The generals said cutting those 15 AWACS will allow the Air Force to reinvest money into bringing on the Wedgetail in 2027, as quickly as possible. And the cuts will also allow the service to concentrate on keeping the remaining AWACS in the air, Guastella said.

Lt. Gen. Duke Richardson, the military deputy for the Air Force’s head of acquisition, said rushing the contract process would not be wise. But once the certification work is done, he said, the Air Force can try to procure more E-7s quickly.

Nahom said Australia has offered to help get American pilots, maintainers and air battle managers trained on the Wedgetail ahead of time, so they can quickly start operating the aircraft after it’s delivered.

Sen. Mark Kelly, D-Ariz., also pressed the Air Force on the budget’s planned reduction in the number of new Compass Calls it would buy. The service originally planned to end up with a fleet of 10 new Compass Calls to replace the aging and retiring EC-130H. So far, the Air Force has bought six of the Gulfstream G550 business jets it will transform into EC-37Bs, most recently in 2021.

Documents supporting the 2023 budget show the service is, at least for now, planning to stop procurement there and not buy any more beyond those six, although its unfunded priorities list asks for another $979 million for the last four G550s.

Compass Call aircraft are used to hack or jam enemy signals overseas. The decades-old EC-130H played an important but less visible role in the wars in the Middle East over the last two decades, interrupting communications and bomb transmissions from groups like the Taliban and the Islamic State.

But some of those legacy EC-130Hs date back to the Vietnam War era, and they are reaching the end of their lives.

L3Harris Technologies won a contract from the Air Force in 2017 to carry out the Compass Call’s crossdeck program, modifying the Gulfstream jets into EC-37Bs and transplanting the electronic warfare equipment into them. BAE Systems is in charge of the new Compass Calls’ electronic components.

Richardson said the first two new Compass Calls are now being modified by L3Harris; the first is on track to be delivered to the Air Force in the first quarter of 2023 to begin testing.

Kelly said a reduction in electronic warfare capabilities would be particularly concerning given the sophisticated air defense systems being fielded by China.

Nahom said the Air Force still wants to get to a fleet of 10 new Compass Calls.

“Six is too small,” Nahom said. “If you take a couple away for training, maybe one or two away for maintenance, you’re not left with a lot for operational use — and there is a lot of use for those airplanes right now.”

But budgetary limitations forced the Air Force to propose cutting the total Compass Call purchase, Nahom said, emphasizing Air Force Chief of Staff Gen. CQ Brown made sure to include the remaining four on the unfunded priorities list.

Richardson said Gulfstream has stopped taking orders for new G550s, but there is a healthy market of used aircraft the service could buy from — if it gets the funding.

Kelly said he’s willing to work with the Air Force to help get those four Compass Call airplanes.

Duckworth also pressed the generals on the service’s plans to stop buying more HH-60Ws after reaching 75 in 2023, a roughly one-third reduction from the 113 the service originally planned to buy.

The Air Force said in March it would cut the number of new combat rescue helicopters as it shifts away from counterinsurgency-focused conflicts and towards potential fights against peer or near-peer adversaries such as China or Russia. That kind of a war would have a highly contested airspace, and the service believes rescue helicopters would be more vulnerable.

But Duckworth wanted to know more about why the Air Force decided a smaller rescue helicopter fleet was worth the risk, and how it would affect the service’s ability to pull personnel out of harm’s way.

Nahom said the Air Force wants to make sure the Guard and Reserve get their full complement of HH-60Ws from the 75 combat rescue helicopters the service now plans to buy. Air Force Reserve units, for example, would need them to help recover astronauts returning from space that splash down off Florida’s coast.

But the Air Force needs to consider what combat rescue will look like in a future contested environment, Nahom said.

“It’s likely not [going] to be in a Black Hawk-type helicopter,” Nahom said. “As we outfit this fleet, we also have to make sure that we don’t spend too much resource on this capability, and then not have the resources to invest in what rescue is going to look like in a contested environment.”

Nahom said the Air Force is still war gaming and conducting analyses to figure out what that future capability will be.

Duckworth asked if the Air Force has considered using other aircraft such as CV-22 Ospreys to conduct rescue operations and lessen the risk that might come from buying fewer HH-60Ws.

Nahom said the Air Force often puts its pararescuemen in a variety of aircraft, including Ospreys, Chinooks, and Black Hawks, sometimes supporting the Army.

Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.

More In Air Warfare