The U.S. Navy’s Unmanned Combat Air System Demonstrator number two achieved aviation history July 10 as the first-ever tailless, stealthy unmanned aircraft to conduct an arrested landing onboard an aircraft carrier.

The landing helps to “make sure that we keep the technological edge” as other nations, such as China, work to build stealthy aircraft and unmanned vehicles, Navy Secretary Ray Mabus said during a press conference on the carrier shortly after the landing.

Though a significant historical achievement, the event underscored that the $1.4 billion UCAS program is experimental as operators quickly implemented a workaround after experiencing an on-deck difficulty after the first landing.

The aircraft conducted two landings, the first of which snagged the number 3 wire as planned onboard the USS George H.W. Bush off the coast of Norfolk, Va., just after midday. The second followed a catapult takeoff from the deck and touched down with the number 2 wire, also as planned.

Both landings appeared nominal, according to Rear Adm. Mat Winter, program executive officer for unmanned aviation and strike platforms. The UCAS took off from NAS Patuxent River, Md., escorted by two F/A-18s.

Prior to the first landing, the UCAS was ordered by the landing systems operator (LSO) on the carrier deck to conduct a go-around, a procedure used to wave a pilot off. The LSO uses a digital interface to relay such commands to the UCAS, and the system’s software translates those commands for use by the aircraft.

One anomaly experienced on the mission occurred as the UCAS operators attempted to hand off control of the air vehicle from an on-deck operator, who uses an arm-mounted device to taxi the aircraft, to a mission operator in the aircraft’s hangar. On the first attempt, the blue light — a signal of a successful handoff — did not illuminate. Instead, operators got a red light, indicating the handoff was not successful.

The handoff is needed so that the mission operator in the hangar can monitor and control the aircraft once it is away from the deck.

The deck crew quickly shifted to a backup arm-mounted deck controller, achieved a blue light signaling a successful control handoff and prepared for the catapult takeoff, according to Capt. Jaime Engdahl, Navy UCAS program manager.

Though not planned, the quick shift to the backup controller validated the modeling and planning leading up to the test. The backup system was there to ensure the aircraft was not stuck on deck for a long period of time, which would be a significant problem in an active air wing where aircraft are constantly landing and taking off from the deck.

The arrested landing is the capstone event and most difficult test for the demonstration program. The first catapult takeoff occurred in May, after which operators conducted more takeoffs and touch and go’s prior to returning to Patuxent River for more work ashore in advance of the landing trials.

However, the landing is more complex because the aircraft’s autonomous software and precision guidance system must accommodate the motion of the carrier on the sea, Winter says. This guidance system allows for the aircraft to know its precise location relative to the ship in preparation for the landing.

The aircraft’s at-sea period on the Bush is slated to end July 16. Program officials hope to achieve at least one more landing prior to the UCAS returning to Patuxent River, Winter says.

Winter says that once air vehicle 2 returns to Patuxent River, operators will sift through the arrested landing test data to see if any more flight tests are needed.

The air vehicles are, however, likely almost finished with their flight careers and both are slated to take permanent residence at naval museums, one in Pensacola, Fla., and the other at Patuxent River, Winter says.

UCAS is a precursor to the Navy’s Unmanned Carrier-Launched Airborne Surveillance and Strike (Uclass) program. Through Uclass, the Navy plans to buy at least two “orbits” — or the ability to conduct two separate 24/7 operations from a ship — for use at sea. The number of aircraft per orbit could vary depending on the different designs offered by various contractors.

Navy Secretary Ray Mabus says affordability is a key requirement for Uclass. Winter says the Navy plans to buy the first two orbits for $150 million or less; that figure does not include the technology demonstration price.

Boeing, Northrop Grumman, Lockheed Martin and General Atomics are all vying for the Uclass contract. Air vehicles designed by each are currently being reviewed by the Navy through a nine-month preliminary design review phase.

In parallel, the Navy plans to issue a draft request for proposals in August to kick off the competition for the aircraft contract. A formal RFP is expected by the end of March 2014, with a downselect by October 2014.