US Navy aircraft carrier fightdeck operations
4.5 acres of American real estate
The flight deck of a Nimitz class aircraft carrier measures some 4.5 acres in size and is always busy and an extremely dangerous place to work. At any time aircraft could be landing at one hundred and fifty miles an hour over the stern whilst others are being prepared for launch from the four super powerful steam catapults. Further aircraft may be being armed and fuelled and yet more positioned in preparation for launch or recovery operations. The operation onboard the flightdeck has, often been described by the crews as a perfectly choreographed ballet and this is a fair analogue for the complicated control necessary to avoid disasters.
The flight deck is composed of various zones. The first is forward over the bows where two of the ships’ four C13 mod 1 catapults are located. The other two are in the waist of the ship and offset to port. The steam catapult was developed by the British in the years after the Second World War with trials onboard HMS Perseus. While the British chose to abandon conventional aircraft carriers in favour of VSTOL aircraft carriers in the 1960’s, the American’s have developed the basic technology to a higher level. The nuclear reactors onboard each Nimitz class carrier are key to the supply of large quantities of super heated and pressurised steam, although, no nuclear steam is used in the catapults themselves. The steam is collected in special cylinders, which store the pressure until released by simply pressing a button to release the potential energy in the form of a slingshot. The pressure available is regulated to correspond with the specific aircraft type and its loading as required for each mission. On the flight deck the aircraft used to be attached to the ‘shuttle’ in the catapult rail with strops or bridles which were jettisoned into the sea. The USS Nimitz, USS Dwight D Eisenhower and USS Carl Vinson all have a large pointed bridle catcher to capture these expensive items at the end of number one catapult. Technology has, however, rendered the use of strops and bridles redundant and all other vessels of the class were completed without bridle catchers.
Behind each of the four catapults is a JBD or Jet Blast Deflector which as the name implies deflects the super hot exhaust gases from the aircraft engines harmlessly away. The JBD’s are angled to deflect most of the energies upwards and away. Each JBD has also got inside it an intricate network of tubes for a-water based cooling system.
The second zone on the flight deck is the angled deck. Another British invention, the angled deck as the name implies is canted from the stern at eight degrees from the centreline of the ship. This allows for aircraft to land without interfering with aircraft launch operations. Furthermore, the use of an angled deck means that if the pilot fails to successfully land his, or increasingly her, aircraft they can fly off the deck and try again. During the era of axial flight decks the aircraft would surely have crashed into other aircraft on the flight deck probably causing chaos and loss of life. On the Nimitz class aircraft carriers the angled deck also has two of the four catapults, numbers three and four along its extreme port side.
To actually land an aircraft probably weighing around four or five tons onto an area probably less than half the size of a football field is a test of a pilot’s skill and nerve. He/She will have to ‘catch the wire’ of which there are four (three in USS Ronald Reagan) stretched out across the angled deck. These can be stressed according to the aircraft types that will be landing. Such information is passed to the controlling officer who is cited in a position in the starboard catwalk that stretches around the side of the flight deck. The stresses of catching a five ton aircraft and bringing to a stop within a couple of seconds is immense and accordingly each of the four arresting cables has its own gear engine rooms. Each is located on the 03 level and it is here that the correct information on aircraft weight is fed into the machinery to catch the ‘birds’ as they fly onto the deck.
The third area on the flight deck is the deck park, this can be any area that is not being used for operational duties. Deck parking of aircraft reduces the pressure on space within the hanger and also allows for aircraft to be properly maintained with a maximum amount of available space. Usually the areas assigned for deck parking are in front and behind of the island and to the port side aft. Interestingly, these are also the locations on the Nimitz class aircraft carriers of the four aircraft lifts. These massive structures can lift a pair of F-14D Tomcat fighters, each weighing 60,000 pounds, from the hanger in a matter of seconds.
Finally, the last zone on the flightdeck is the ‘carriers island structure. When the aircraft carriers of this class are built by Newport News Shipbuilding, the island structures are lifted into place as one component and subsequently welded into place. The island is the control centre for the entire ship from here the ships are navigated, fought and the air force onboard is commanded. Therefore the island has been designed to facilitate the best use of space. Stacked upon a pedestal mounting, the island has three levels, the top most is effectively the control tower for the movement and control of the aircraft and personnel on the flightdeck. The next level down is the Navigational Bridge from where the ship is navigated and commanded. Finally, the third level down is the Flag Bridge, which is used by an Admiral and his staff when they are embarked onboard the carriers. The dimensions of the navigation bridge on a Nimitz class carrier are surprisingly small just about forty feet from port side to starboard side and just ten feet deep. There is an auxiliary conning station that extends from the starboard side of the bridge with large windows on three sides for improved visibility. Meanwhile, the main navigation-bridge provides excellent views in all directions and across the flight deck. Towards the back of the navigation bridge is a passageway that leads away from the bridge itself.
The zones on the flight deck are also given nicknames by the crew - each implying as to its function or location on the flightdeck. Therefore crew onboard a Nimitz class ship can be heard referring to places such as “The Crotch”, “Hummer Hole” and “The Junkyard”.
A flight deck is, however, nothing without the personnel to take charge of the seeming chaos that is an operational carrier’s deck. In the United States Navy crewmembers wear different colour jackets to denote the role they play on the flight deck. Therefore those wearing Yellow are aircraft Directors who orchestrate the movement of aircraft. Blue shirted personnel are to be found in charge of the chocks and chains that hold down the aircraft. Red shirts are those who arm the aircraft for missions. Trouble shooters and crewmembers in charge of safety onboard the flight deck wear white shirts. All essential maintenance on the deck is carried out by engineers wearing green. ‘Grapes’ or purple shirted personnel carry out all fuelling operations and finally the Brownshirts are the Plane Captains who prepare the aircraft for flight.
It is no understatement to say that if a catapult launch is hazardous, landing on the aircraft carrier is doubly dangerous. The ship is moving in three directions, the speed of approach can be anything up to two hundred knots, the possibility of aircraft on the ramp and possible battle damage to the aircraft can also not be discounted. Add to this that the landing may be at night in combat conditions with the carrier blacked out the dangers became all too apparent.
To assist the pilot a landing aid is positioned on the port side of the ship aft. It is stabilised and shows the pilot the correct angle of approach that he/she should take to make a safe and correct landing. Modern combat aircraft are heavy and complex machines and because of this the speed of approach to the aircraft carrier has to be fast so as to avoid a disastrous stall. As such an approaching aircraft has to slam onto the deck in a procedure that has often been described as little more than ‘controlled crashing’.
Combat naval aircraft are equipped with a tailhook that is deployed on approach to catch one of the four arrestor wires stretched across the rear quarter of the angled deck. These steel cables are stretched taut by powerful hydraulic cylinders found below the flight deck. They are made of super strong braided steel, but still there have been occasions when they snap and when they break they can become lethal as they whip around the flight deck. To give some idea of how tautly the wires are stretched, each one can break an F-14 Tomcat in three hundred feet in two seconds. As you can imagine this manoeuvre puts a great deal of physical strain onto the aircrew inside the aircraft.
If the pilot makes a bad approach and doesn’t catch any of the four wires, he will ‘bolt’. This means he slams his engines onto full and flies straight back off the angled deck of the carrier, climbs and re-enters the pattern to attempt a second landing. Interestingly, when pilots catch the wire, they still slam the engines into full just to be sure. Once secure in the knowledge that they have been caught on the flight deck the pilot will shut his engines down. The flight deck crew will quickly and efficiently move the aircraft to a parking area and clear the angled deck for any other incoming aircraft.
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