ABOARD THE USS THEODORE ROOSEVELT — The U.S. Navy executed its first-ever takeoff and landing of unmanned and manned aircraft in rapid succession on an aircraft carrier deck Aug. 17, putting the service one step closer to its goal of a mixed fleet of manned and unmanned aircraft in the coming years.

This also marks yet another seminal event in the X-47B Unmanned Combat Air System (UCAS) program, funded with roughly $1.5 billion by the Navy and managed by prime contractor Northrop Grumman. The goal of this set of tests was to validate whether unmanned aircraft — operated from an onboard mission control center for its flight but overseen by human handler once on deck — can be integrated into the fast-paced flow of a carrier air wing using catapult launch and arrested landing systems. Navy officials invited a handful of media to witness the event roughly 112 nm off the coast of NAS Oceana, Virginia.

As with almost any test program, the trials did not go as planned. But by the afternoon, the Navy had accomplished some aviation firsts. These were the first-ever cooperative Navy aviation tests on a carrier, including manned and unmanned aircraft landings and takeoffs in succession. The goal is to eventually craft unmanned aircraft capable of operating in the typical carrier air wing tempo — taking roughly 90 sec. to launch from a catapult and about 60 sec. to land and clear the runway for another landing.

Though not achieved while the press were watching the trials, the first-ever cooperative arrested landing and take off also took place. X-47B ship 501 landed and properly employed its new automatic tailhook retractor as well as automatic wing fold using new software. The on-deck operator, paid by Northrop Grumman, also quickly taxied the stealthy aircraft off the runway path, allowing an F-18 to land in its place. Though eventually this must happen in 60 sec. to mesh with actual ship operations, this first attempt took about 90 sec., according to Capt. Beau Duarte, the Navy’s X-47B program manager.

The cooperative takeoff was more thorny. A first attempt was marred by the ship’s position; the runway’s attitude was just slightly below the horizon, Duarte said. Experimental aircraft are prevented from flying off deck unless the attitude is level or higher than level; ship operators shifted fuel on the carrier to level the deck. It is unclear why the test director launched the F-18 if the deck attitude was wrong, or whether the ship shifted in the seconds following the Hornet launch.

About 150 sec. separated the second cooperative takeoff attempt between the F-18 and the UCAS. "What you saw today was history," said Rear Adm. Mat Winter, program executive officer overseeing the project. "It is not unmanned over all others. It is a blending of manned and unmanned."

Four more one-hour flight test periods were planned for UCAS after the one witnessed by media. The goal was to continue condensing the flow time between the manned and unmanned takeoffs and landings, and if time permits, experiment with night-time deck handling of the X-47B. Operators in a containerized mission control area in the belly of the ship control the aircraft during its flight. Once on deck, an on-deck operator handles the aircraft using an arm-mounted device. This is used for taxiing, lining the aircraft up into the catapult and wing fold and tailhook retraction. This operator also has voice connectivity to the air boss, as would any pilot in a manned aircraft.

Navy officials are eyeing another potential set of ship trials; these under way now are the fifth time the system has been onboard a carrier for testing. Next up could be more testing of operations in off-nominal winds. The next possible slot is in the first quarter of 2015.

The X-47B program was to be shelved, but senior defense officials directed the Navy to continue testing to gather more data on how to infuse unmanned aircraft into the carrier air wing. Another possible test point, if approved, would be autonomous aerial refueling using ship 502, which was not used Aug. 17 during the testing witnessed by the media. Owing to a fuel-pump issue it stayed ashore at NAS Patuxent River, Maryland.

Data from these tests will are being used to populate various models for the program that could influence the design of the follow-on Unmanned Carrier Launched Airborne Surveillance and Strike (Uclass) system.

A long-awaited request for proposals will be issued in secret to four potential bidders early next month, Winter says. Lockheed Martin, Boeing, General Atomics and Northrop Grumman are planning to offer bids.

Editor's Note: This story was amended to update the U.S. Navy's cost estimate for the UCAS program.