ABOARD THE U.S.S. GEORGE H.W. BUSH — At 11:19 a.m. today, for the first time in history, a plane without a pilot in it executed one of the most complex missions in aviation: launching off an aircraft carrier at sea. Only the Navy can’t yet land that drone aboard the U.S.S. George H.W. Bush, an even harder but necessary maneuver if large drones are really going to operate off carriers.

On a crisp, bright and nearly cloudless day, about 100 miles off the Virginia coast, the crew of the Bush and the team behind the highly autonomous X-47B loaded up the deck’s second catapult with the drone and shot it off into the sky above the eastern Atlantic. The drone — which has its own callsign, “Salty Dog 502” — turned downwind and passed over the ship twice, first from 1000 feet overhead and then from 60 feet overhead, before flying back to dry land in Maryland. The launch went exactly as the Navy hoped.

With that, the era of the drone took a major step toward patrolling the skies above the world’s waterways. It’s something the Navy hopes will have big implications for supplementing manned fighter jets in a carrier air wing, providing both persistent surveillance far out at sea and ultimately firing weapons in highly defended airspace that might mean death for human pilots.

Senior Navy officers openly likened the X-47B’s launch off the Bush to the first-ever launch of a plane off the U.S.S. Birmingham in 1910. “It’s one small step for man,” remarked Rear Adm. Matt Winter, the Navy’s chief program officer for unmanned systems, “and one significant technical step for unmanned-kind.”

Winter is right: the launch is legitimately historic. No nation possesses a drone that can operate off the deck of an aircraft carrier, a complex and dangerous environment that requires years of pilot training and constant deck-crew coordination. When the X-47B shot from the catapult off the Bush on Tuesday, it took a big step toward proving the U.S. will be the first. The X-47B is just a demonstrator aircraft: it will soon give way to the Unmanned Carrier-Launched Airborne Surveillance and Strike (UCLASS) robot that the Navy wants to integrate into its carrier air wings by the end of the decade. Today, the X-47B demonstrator demonstrated a lot.

But the X-47B, a Northrop Grumman creation, is a step ahead of other drones in another way. Almost all drones of its size — with a 62-foot wingspan, it’s bigger than a Predator and about on the scale of a manned F/A-18 Super Hornet — are flown by human beings. Those human beings might be thousands of miles away from the drone, in a cramped and freezing-cold Ground Control Station, but they have instruments that give them physical, real-time control of how the drone flies and what it sees — a very remote cockpit. The X-47B is different: its flight plan is pre-programmed, a matter of an algorithm, and the drone executes it autonomously, relying on GPS. The human back on board the ship only overrides it if something goes wrong.

“The Navy’s model is different from the Air Force’s,” said Rear Adm. Ted Branch, the commander of Naval Air Forces Atlantic. “We don’t have someone actively flying this machine with a stick and a throttle. We fly it with a mouse and a keyboard.” In military nomenclature, the Air Force has drone pilots; the Navy has drone operators.

Today’s launch has been planned for months and anticipated for years. Earlier this month, at the Navy’s aviation test hub in Maryland, known as Pax River, the X-47B touched down and caught the arresting wire on a mock carrier deck. Catching the wire, or the “Trap,” is as difficult as it is necessary to keep a plane from careening off the carrier and into the water. While it was a positive sign that the Navy’s new robot demonstrator could do it, the X-47B’s successful Trap catch was still on dry land.

And so it was today. The Navy programmed the X-47B to take off from the Bush and land back at Pax River. Navy officials, including X-47B program manager Capt. Jamie Engdahl, say that the X-47B will actually conduct its first carrier landing at sea around July or August. Engdahl and other Navy officials say they still have to perform more tests before the X-47B is capable of landing on a carrier, particularly to ensure that the robot’s so-called “relative navigation” systems — which ensure it can catch a moving target like a ship at sea — can place the drone precisely where it needs to be on the carrier deck to catch the Trap. “We did not accomplish all the land-based field testing,” Winter told reporters. Engdahl said he opted not to wait.

It remains to be seen whether the Navy will invite the same media spectacle aboard a carrier for the drone’s first landing as it did for the first launch. The Navy paused normal flight operations aboard the Bush while reporters helicoptered out to film the event. Navy officers and Northrop Grumman officials cheered when the X-47B launched and then flew back over the ship. But no one would commit to letting the media return for the carrier landing, suggesting the Navy doesn’t have total confidence in the demonstrator’s ability to execute among the hardest maneuvers in aviation while news cameras roll.

The X-47B has had some difficulty making the Trap on dry land, which helps explain the Navy’s reluctance to bring the robot down onto the Bush today. But difficulties catching the arresting gear ought to be expected: the Navy is literally doing something no drone has ever done before. Failure is a necessary component of testing. Don Blottenberger, one of Engdahl’s deputies, said the drone probably has maybe 10 more land-based landing tests at Pax River before it’s ready for its carrier landing.

After the carrier landing, the next step for the $1.2 billion program is to execute an autonomous mid-air refueling mission, also scheduled for this year. Only it won’t happen with the X-47B exactly: a Lear Jet will be specially equipped with the X-47B’s software and some of its hardware. After that, Blottenberger said, “We’re gonna be done.” The X-47B program will stand down and the UCLASS program will begin. The X-47B may end up in a museum.

The carrier launch is an important demonstration. The forthcoming carrier landing will ultimately prove that drones can join an aircraft carrier airwing. For Engdahl — who ended his pre-launch speech with an enthusiastic “God bless America!” — the difference doesn’t ultimately matter to the robot.

“It’s a UAV,” Engdahl said, using the acronym for Unmanned Aerial Vehicle. “It doesn’t know it hasn’t been landing on the boat for the last six months.”