Monday, November 10, 2014

How it Works: F-35C Carrier Operations

October 28, 2014 - Aircraft carriers provide a vital first line of defense for militaries around the world. But, operating an aircraft from a ship hundreds (and sometimes thousands) of miles from shore is not for the faint of heart. In fact, it can be downright nerve-wracking for even the most experienced pilot.

The F-35C at Sea

The F-35C carrier variant combines the unique capability of operating from a carrier deck with the unmatched 5th Generation capabilities of stealth and sensor fusion, making the F-35C the Navy’s first low observable stealth fighter at sea.
The F-35C is designed and built explicitly for carrier operations. It has larger wings and more robust landing gear than the other variants, making it suitable for catapult launches and fly-in arrestments aboard naval aircraft carriers. The F-35C’s wingtips also fold to allow for more room on the carrier’s deck while deployed.
In addition to the F-35C, the F-35B variant is also built for aircraft-capable ship operations. With its unique short takeoff and vertical landing capabilities, the F-35B is designed to operate from austere bases and a range of air-capable ships near front-line combat zones. In 2012 and 2013, the U.S. Marine Corps, U.S. Navy and Lockheed Martin teamed up to test the F-35Bs ship suitability in ship trials known as Developmental Test 1 and 2 (DT-1 and DT-2, respectively).
With F-35B ship trials complete, the F-35C is now on deck – literally. Starting this year, Developmental Test 1 (DT-1) for the F-35C will commence aboard the USS Nimitz to test normal carrier operations, as well as the new arresting hook package.

An Inside Look at F-35C Carrier Operations

To get a firsthand account of how daily procedures are performed on a ship, we sat down with Lockheed Martin F-35C expert and retired U.S. Navy Captain (Ret) Tom Halley:

1.  Let’s start from the beginning. How do the aircraft launch from the ship?

Tom Halley: A typical “day” on-ship is about 15-18 hours, with approximately 13 hours of that being launch and recovery on a one and a half hour cycle. Ships today use steam-powered catapults (cats), and can typically launch 15 aircraft per cycle at a time within seconds of each other using both sets of two cats (two on the bow and two on the waist). The launch and recovery of aircraft is performed as fast as possible to limit the amount of time a ship is turned into the wind. When turned into the wind, a ship is predictable and therefore vulnerable to the enemy.

2.  After the pilots have completed their mission and are coming back to land on the ship, what happens?

Tom: As pilots, we are innately aware of several things going on with our aircraft at all times – one of those is our fuel level. Luckily with the F-35, keeping track of this will be easier on our pilots due to the advanced avionics, sensor fusion and helmet display that keep this information at the pilot’s fingertips. Plus, the F-35C carries almost 20,000 pounds of fuel internally, which is approximately 6,000 pounds more than our current fighter fleet. When a pilot’s mission is complete, or when we are running low on fuel during a routine carrier sortie, we head back to the ship in order to make our recovery time. Fighter aircraft are always first to land since they have a higher burn-rate of fuel and typically have a lower fuel capacity than other aircraft.

During daylight hours and good weather conditions, a pilot will monitor tower frequency while overhead the carrier to keep in contact with the Airboss. “The Boss” as we call him, is responsible for everything that goes on aboard the flight deck and the airspace inside 10 nautical miles of the carrier. We will monitor his tower frequency, but the entire recovery is done “Comms Out.” In other words, for the entire launch and recovery, pilots shouldn’t hear any radio transmissions if the launch and recovery is going well.

As pilots come back to the boat, each squadron is assigned an altitude overhead the carrier and is put into a “stack” above the boat. For instance, my squadron might be overhead at 3,000 feet, our sister squadron will be at 4,000 feet and the E-2D squadron(less fuel dependent) might be at 7,000 feet. Depending on the number of aircraft, a pilot could have another jet 1,000 feet below and above them in a holding pattern until it’s their turn to land. When at the bottom of the stack, one cardinal rule is that you never descend until you are aft and abeam of the boat. This is a safety measure that keeps jets at 5,000 feet from descending through the middle of the overhead marshal stack. Trust me, it happens!

3.  Let’s say I’m now at the bottom of the stack and it’s my turn to come in for a landing. As a pilot, what do I do?

Tom: When at the bottom of the stack, pilots are, what we call, “hawking the deck,” which means that they are still circling, but have a keen eye on the flight deck to watch for the last aircraft to be shot off the catapult. As soon as this last aircraft clears the catapult, our pilots have about a minute until the deck will be ready for them to catch the wire, or trap as we call it. A good flight lead will have his section or division of aircraft approaching the stern of the ship for the “break” to land as soon as the last plane leaves the deck.

When at the stern, or back of the boat, pilots are at 800 feet in right echelon. When it’s time for them to land, the lead aircraft will break and his wingmen will break about 17 seconds afterwards. This will allow for the perfect 45 second interval between all landing aircraft. Once a pilot is downwind and heading toward the stern of the boat, they can descend to 600 feet. At this point, the pilot is 1.2 to 1.3 miles from the back of the ship and should have their gear down, flaps full down and arresting hook down. This is the start to a perfect approach.

Once in position, our pilots will start their left-hand descending turn to line up with the landing area on the boat. This is no easy task because the boat is always moving away from them, so beginning the turn at the back of the ship sets them up for a nice start to their landing. The second challenge is that the runway is on an eight degree angle to the left from the line the boat is traveling on. This slight angle means our pilots are constantly correcting for line-up as they’re coming down the chute.

Once lined up with the landing area, pilots use the data on their cockpit displays and a tool called the Fresnel Lens, or “ball,” on the deck of the ship to guide them to the wire. The Fresnel Lens is simply an amber light centered between two horizontal rows of green lights that lets each pilot know where they are on the glide slope at all times during the descent. If the “ball” is above the horizontal row of green lights, the pilot’s aircraft is high. If the ball is below the green lights, they are approaching low. If the ball shows red, the pilot is really low and could be in danger of hitting the boat, known as a ramp-strike. This is definitely not good.

As a second line of defense, all landings are monitored by a team of Landing Signal Officer’s (LSO) that are stationed just to the left of the landing area to watch every landing and grade that landing for safety. All LSOs are also pilots themselves. If there is trouble with an approach, the LSO will come on the radio and tell the pilot to add power, check his line-up, or wave-off if they’re making an unsafe approach. Ideally, if a pilot has a good start, flies a smooth approach, constantly corrects line-up, and keeps the ball in the middle of the lens they’ll be rewarded by catching a three- wire, which is considered excellent in terms of landings.

There are four arresting wires stretched across the deck and the Fresnel Lens is usually adjusted for the pilots to target the three-wire. This means that the pilot snags three of the four wires with their arresting hook when landing. Once a pilot’s wheels touch down on the flight deck, they instantly go to full power on their throttles. That may seem counter-intuitive, but if you miss the wire and you pull the throttle to idle you’re going to be going swimming because the plane will not have the power to get airborne again. If they do miss the wires and go to full power they’ll be fine. This maneuver is called a “bolter.”

Once a pilot has successfully caught the wire and gone to full power, they’re going from about 145knts to 0knts in two seconds. It’s pretty eye-opening. Once they’re safely in the wire, one of the taxi directors will tell the pilot to throttle back and raise your hook. The pilot then quickly taxis out of the landing area because the next plane is probably already in the landing groove. Every 45 seconds this will happen until the recovery is over, then these planes will be turned around, refueled and made ready for the next launch.

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