The Navy this week completed a second round of sea-based testing of the communications software that will be used to guide its envisioned aircraft carrier-based unmanned aerial vehicle on take-offs and landings, the service said yesterday.

The four days of testing aboard the USS Harry S. Truman (CVN-75) concluded on Tuesday under the Unmanned Combat Air System Demonstration (UCAS-D) program, which is precursor to the follow-on program known as Unmanned Carrier Launched Surveillance and Strike (UCLASS).

Northrop Grumman [NOC] has built two X-47Bs for UCAS-D program that have undergone flights but have not been used for the sea-based testing. Instead the Navy has used surrogate aircraft equipped with the software to represent the systems on the X-47B.

The testing is “looking for confirmation that our systems are properly monitoring the unmanned surrogate aircraft," said Lt. Cmdr. Chad Young, the Truman’s assistant air operations officer. "This testing will eventually lead to unmanned aircraft landing on and launching from U.S. Navy aircraft carriers."

The first UCAS-D test took place in June 2011 aboard the USS Dwight D. Eisenhower (CVN-69). Lt. James Reynolds, the UCAS-D surrogate project officer, said the testing aboard the Truman better represented the X-47B’s software following some modifications needed after last year’s test.

"We’re refining the system," he said.

The UCAS-D program, based at Naval Air Systems Command (NAVAIR), is designed to produce an unmanned, carrier-based intelligence, surveillance and reconnaissance (ISR) aircraft with the ability to carry out precision strike operations.

Navy officials had hoped to have either a UCLASS system deployed with the fleet’s carrier groups by 2018 under initial operational capability, but that has been delayed until at least 2020, Navy Secretary Ray Mabus said Feb. 16.

The Navy last summer issued four separate UCLASS research and development contracts to Boeing [BA], General Atomics Aeronautical Systems, Lockheed Martin [LMT] and Northrop Grumman [NOC].

Rear Adm. Joseph Mulloy, deputy assistance secretary of the Navy for the budget, said Feb. 13 that the UCLASS program was pushed back because an analysis of alternatives has not been completed and the “program was already sliding some.” The service also needed to better define the requirements, he said.