Talking to No One
The story of one naval aviator who helped land the first autonomous unmanned aircraft aboard a carrier
05 August 2013
Three and a half seconds.
That's about the time it takes for the average person to put on their seatbelt and start their car. It's also the window of time Lt. Cmdr. James Reynolds had sole responsibility for the safe landing of a multi-million dollar unmanned autonomous aircraft, the X-47B, on the deck of USS George H.W. Bush (CVN 77) at sea.
Reynolds is an F/A-18 Hornet pilot and a qualified landing signal officer. LSOs are the pilots who stand on the aft port quarter of an aircraft carrier and help guide pilots down during the last seconds of the approach. It's a job that dates back to some of the earliest days of naval aviation.
"It's something that happens very early in your career," said Reynolds. "When you get into your first fleet tour; typically, it's a squadron need sort of thing."
Little did Reynolds know that when he qualified as an airwing LSO aboard USS John C. Stennis (CVN 74) in 2007 that it would ultimately put him in a position to play a pivotal role in naval aviation history - unmanned autonomous landings at sea.
For manned aircraft, such as the Hornet, LSOs typically take sole "control" of the aircraft at approximately three quarters of a mile from the ship, talking and guiding the pilot in on the correct guide slope. For the X-47B, Reynolds took control just a little further out at a little over a mile. However, the aircraft was programmed to land itself and didn't take its directional cues from the LSO like a manned plane would.
As the X-47B approached the flight deck, a couple of people still had the ability to tell the aircraft to wave off, but there quickly became a point where the LSO was in sole control of the decision to either let the aircraft land or wave off and try again.
"So, all the other sources that could generate a wave off, even internal to the aircraft - all those automatic wave offs are inhibited inside of three and a half seconds, and the LSO is effectively the only one who can command a wave off at that point," said Reynolds.
It's All In the Pickle Switch
So, how exactly does an LSO talk to an unmanned aircraft that doesn't have a pilot?
LSOs have a "pickle switch," or handheld remote, that controls what "the ball" displays. LSOs also have a handheld radio to communicate with pilots, and when an LSO calls out "Roger, ball," it signals to everyone listening that he is in control of the approach and the pilot is cleared to continue to land.
The pickle controls what lights are displayed on the ship's optical landing system. In a manned aircraft, the green lights signal the "cut lights," which signals the pilot to continue the approach. They are also used to tell a pilot to add power during the landing. Red lights signal a "wave off," which tells the pilot to abandon the landing, add throttle and go around for another attempt.
"When you're calling 'Roger, ball' for a manned aircraft, it's about 18 seconds from that point when the airplane touches down," said Cmdr. Matt Pothier, the officer in charge of the Navy's landing signal officer school at Naval Air Station Oceana, Va. "So, really what's critical about that three and a half seconds is, probably about 10 to 12 seconds into your approach, you're getting into a precarious position. You're not quite safe enough to land, but you still have some time to change your parameters."
It's during this time that an LSO has the sole responsibility to decide if a pilot, or an unmanned system like the X-47B, is safe enough to land or it should wave off and try again.
For the X-47B, the same trigger and switch on the pickle that controls the lights on deck also send the digital permission signal to the aircraft.
"As the [X-47B] starts the approach, there's a couple of extra checks I have to do to make sure that the messaging between the pickle switch that we use to wave the aircraft off or give it the cut lights - to make sure that when I hit those buttons the correct messages are sent to the aircraft," said Reynolds. "As it comes in, the mission operator calls the ball, just like in other aircraft. The LSO rogers the ball up. I hit the cut lights, and that's kind of the digital consent for the aircraft to land."
Reynolds said if the X-47B doesn't get any signal at all, it's programmed to wave off at 200 feet above the water and come around to try again.
In some ways, being an LSO for the X-47 harkens back to the early days of naval aviation, when LSOs didn't have any radio communication with pilots. LSOs started out by waiving signal flags and then large colored paddles to convey to a pilot that his approach was too high or too low, too fast or too slow as he focused on catching the plane's tailhook on deck. During the early years of carrier aviation in the 1920s and 30s, this was just about all the feedback pilots received when approaching a ship for landing.
Later, as technological advances made their way to the fleet, the ship added a system of colored lights, known as "the ball," to assist aviators.
"Back in the 50s, as they started developing the new lens, the optical landing aid system to help airplanes land, they thought then that they could get rid of LSOs," said Pothier. "The accident rate increased dramatically when they got rid of the LSO, so they immediately brought them back into the fold and the accident rate obviously diminished."
X-47B Development
Fast forward to 2007. A contract was awarded to Northrop Grumman to design, produce and begin testing two X-47s for the Navy to demonstrate the ability of an autonomous aircraft to safely launch and recover on an aircraft carrier. The X-47B is shaped like a flying wing and has no tail.
After five years of development and testing ashore, (the X-47B was put through more than 160 test approaches and six arrested landings at Naval Air Station Patuxent River, Md.,) the X-47B began ramping up for its sea trials in late 2012, when the Navy decided to put one of the aircraft aboard USS Harry S. Truman (CVN 75) to test its ability to taxi around the flight deck.
In February of that same year, Reynolds reported aboard VX-23, a Navy air test and evaluation squadron, and found himself working closely with software and hardware engineers from Northrop Grumman to get the X-47B ready for a carrier landing.
On July 10, 2013, he got a chance to put his training to the test aboard USS George H.W. Bush (CVN 77). With the secretary of the Navy, the chief of naval operations and the media all standing behind him on the LSO platform, he landed the X-47B twice.
An X-47B Unmanned Combat Air System completes an arrested landing on the flight deck of the aircraft carrier USS George H.W. Bush (CVN 77) July 10, 2013. The landing signal officer, Lt. Cmdr. James Reynolds, can be seen with a group of observers in the bottom right of this photograph. (Photo by Mass Communication Specialist 1st Class Arif Patani)
"It's good to come to the culmination of quite a bit of work," said Reynolds. "And not just work on my part, but years of work on the part of the team.... So it's satisfying to kind of help them get to the point where we can successfully interface with the ship."
It was a feat in aviation precision that is truly difficult to appreciate for those unfamiliar with all the nuances.
"On a standard aircraft carrier, the targeted hook touch down point, meaning the place where you're supposed to land from the back of the ship, is only 230 feet away," said Pothier. "On the Bush ... it's 205 feet down. Then that also corresponds to a safe height.... On the Bush, [that's] 12 and a half feet from the back of the ramp. So, if you're exactly 12 and a half feet and you're flying exactly three and a half degree glide slope angle, your hook will land 205 feed down from the landing area. So, when we teach pilots how to do this, if they have just a slight margin of error, so say they are one foot high or one foot low, they're going to miss that optimum targeted hook touchdown point."
To get a flying robot to accomplish the same thing is, understandably, something the Navy was very excited about.
"It isn't very often you get a glimpse of the future," said Secretary of the Navy Ray Mabus after observing the historic landing. "Today, those of us aboard USS George H.W. Bush got that chance as we witnessed the X-47B make its first-ever arrested landing aboard an aircraft carrier. The operational unmanned aircraft soon to be developed have the opportunity to radically change the way presence and combat power are delivered from our aircraft carriers."
The Navy completed all of its objectives for the X-47B's carrier demonstration phase in July. The Navy plans to use the data collected from the aircraft's tests and evaluations to build into the next generation of autonomous aircraft. No one is quite sure yet how LSOs will interact with future unmanned autonomous flying systems, but Reynolds makes a strong case to keep them involved.
"As we move to automated approach systems like this one, where the aircraft is essentially being flown by computer code - computer code is good at doing something very fast, but it doesn't think creatively and it doesn't adapt. The LSO is always going to have to be there to make sure that if there is a failure, if something goes wrong, that the aircraft is handled effectively and safely."
The following people and commands contributed to the production of this article: Mass Communication Specialist Seaman Travis Litke and Mass Communication Specialist Seaman Chase Martin with USS George H.W. Bush media department, and Naval Air Systems Command Public Affairs.