The US Navy has launched flight testing on the Northrop Grumman MQ-4C Triton of one of the first active electronically scanned array (AESA) radars with 360-degree coverage that was developed exclusively for the maritime patrol mission.

The Northrop multifunction active sensor (MFAS) completed first flight on board the MQ-4C on 18 April following an extended risk reduction phase on a Gulfstream GII testbed.

“We’re very confident the radar is going to work,” Sean Burke, the navy’s MQ-4C programme manager, told reporters about five days before the test flight.

Burke cited the 42 test flights already completed on the GII testbed as the source of the navy’s confidence in the new sensor. “The radar modes are working very well for us,” he says. “Now what we’re worried about is the integration effort.”

The MFAS forms the heart of the $12.8 billion MQ-4C’s programme’s surveillance capability.

A decade ago, the navy conceived of a broad area maritime surveillance fleet of unmanned air systems (UAS) to augment about 117 Boeing P-8A anti-submarine warfare and maritime patrol aircraft. The MQ-4C would be tasked with maintaining five continuous surveillance orbits above 50,000ft over vast swaths of the world’s oceans. The MQ-4C would use onboard sensor suite to detect possible threats and queue the P-8A or other aircraft to either take a closer look or attack.

Northrop’s proposal based on an AESA sensor adds a new capability in maritime patrol. Other UAS and manned aircraft operating a similar mission profile typically used a mechanically-scanned or rotating array to achieve 360-degree coverage.

The MFAS test flights on board the MQ-4C are critical to informing a navy decision at the end of this year on whether to launch low-rate initial production of a Triton fleet expected to number 70 aircraft.

An initial capability is scheduled to become operational in May 2018 with radar and electro-optic/infrared sensors. An upgraded version of the aircraft is scheduled to become operational between July and September of 2020 with a low-band and high band signals intelligence system.

Meanwhile, the navy is working to reinsert a due regard radar (DRR). That sensor was dropped two years ago after the contractor, Exelis, struggled to meet performance requirements. The DRR provides the aircraft’s “eyes” as it descends through air traffic, detecting low-flying aircraft against ground clutter. Northrop has developed a way to improve the Exelis DRR payload, the navy says. Until it is available, the due regard function for the MQ-4C will be performed by ground-based or ship-based radars, Burke says.