The US Navy's P-8A Poseidon could pick up a new mission if the US Air Force is allowed to follow through on plans to cancel a replacement for the Northrop Grumman E-8C JSTARS.

The navy is buying 117 P-8As to perform anti-submarine warfare and maritime patrol missions, but a subset of the fleet is being equipped with Raytheon's Advanced Airborne Sensor (AAS) radar.

Raytheon also offered a version of the AAS to the USAF for the JSTARS recapitalisation competition, but it was rejected in favour of a Northrop system.

But the sensor performs the same mission as the Northrop APY-7 on the E-8C: offering wide-area ground surveillance with a ground moving target indicator mode.

"If [the air force] were to get out [of the E-8C JSTARS mission area], could a similar radar on a P-8 be a possibility? Potentially," says Capt Tony Rossi, P-8A programme manager for Naval Air Systems Command.

But Rossi casts doubt on whether the USAF would be allowed to simply drop plans for recapitalising the E-8C fleet, noting that the US Department of Defense or Congress could step in to prevent such a move.

The USAF launched the "JSTARS Recap" programme three years ago to replace the 17-strong E-8C fleet, with aircraft options ranging from the Bombardier G6000 to the Gulfstream G550 and the Boeing Business Jet version of the 737-800.

By mid-2017, however, the USAF began expressing concerns about the JSTARS Recap platform options. Two months ago, the USAF released a budget request for Fiscal 2019 to Congress with the JSTARS Recap line item deleted. The proposed platforms would not survive in combat after 2025 as air defence technology advances, the USAF says.

Although the navy's P-8A is also based on the Boeing 737, Rossi believes the Poseidon does not share the same vulnerabilities as the USAF's E-8C fleet. The P-8As mainly hunt for submarines in the deep ocean, far from land-based integrated air defence systems. As a weaponised surveillance platform, the navy's concept of operations for the P-8As also differs significantly from the air force's unarmed E-8Cs.

But the USN has been slowly developing an expertise in overland, wide area surveillance. By 2006, the USN had deployed Lockheed Martin P-3s with the Raytheon Littoral Surveillance Radar System. As the P-3s are replaced by the P-8A, the USN selected Raytheon's AAS to provide a similar capability, using an active electronically scanned array radar.