The US Air Force has selected Lockheed Martin’s Infrared Search and Track (IRST) system for its Boeing F-15C, but a potential freeze on Pentagon dollars could delay delivery.

President Donald Trump’s proposed fiscal year 2018 budget included $57 million for an IRST upgrade to the F-15C fleet. But if Congress refuses to pass a long term budget, the Defense Department will be forced to operate under a continuing resolution that would maintain funding at the previous fiscal year level. Lockheed plans on delivering its first Legion Pod to the USAF in 2018, but since the programme is considered a new start it could risk a delay under the continuing resolution.

IRST, a passive air-to-air radar system that detects airborne threats in radar denied environments, is already fielded on the US Navy’s Boeing F/A-18E/F fleet and international F-15 aircraft. Budget woes have hit the USAF’s IRST implementation previously. Though never a joint programme, the USAF and Navy shared identical requirements for IRST, but while the Navy went ahead with IRST, the USAF had funding issues in 2010 and set the programme aside, says Don Bolling, director of business development at Lockheed missiles and fire control.

“Now we’re at an opportunity where we can bring the programmes back in alignment,” he says.

Lockheed plans to deliver engineering, manufacturing and development pods in 2018, with a fielded capability for the USAF by 2020, Bolling says. The navy and USAF configurations only differ in their “wrapper,” with the navy’s IRST inside a centerline fuel tank and the air force’s version inside Legion pod, he adds.

Boeing and Lockheed have discussed a future F-15 configuration, though Bolling says he’s not sure at this point whether Boeing’s “Advanced F-15” will entail different sensor configurations or airframe modifications.