Fighter Wing: A Guided Tour of an Air Force Combat Wing

by Tom Clancy

  Using the control stick to fly the refueling boom into position over the receiving aircraft’s receptacle, the boomer activates a switch which stabs the refueling probe of the boom into the receptacle, causing it to “hard latch.” This last part of the operation can be tough, especially in rough air, and may require several attempts to get it right. The two aircraft are now joined, flying just a few yards/meters apart, and the boomer relays this fact to the flight deck, where the flying crew actually controls the pumping of fuel down the boom to the receiving aircraft. Though the pumping is fairly rapid, fully refueling a tactical aircraft like the F-15E Strike Eagle or the F-16 Fighting Falcon does take a few minutes. Meanwhile, both aircraft are flying an oval “racetrack” course at about 300 knots/545.5 kph. at an altitude of 20,000 to 25,000 feet/6,060.1 to 7,575.8 meters. One of the more interesting features of this aerial dance is that once the two aircraft are hooked up, they can talk plane-to-plane over a special intercom link, which allows the pilot of the receiving aircraft to report battle damage or other problems, and to receive updates on targeting and scheduling changes. For many pilots during the early hours of Desert Storm in 1991, the last thing they heard before going into combat was the reassuring voice of a Boomer on the intercom, wishing them well and a safe return. Since the two aircraft are only about 35 feet/10 meters apart, the receiving aircraft can take a severe buffeting from the tanker’s wake turbulence. It’s tough to maintain a position, even for a skilled pilot, especially at night, in bad weather, when you are low on gas.

  To the aircrews of combat aircraft returning to base, shot full of holes and leaking fuel all over the sky, every drop on a tanker is precious. Happily, the KC-135R tanker can carry a lot of fuel—some 203,288lb./92,210kg., which translates to a capacity of about 25,411 gallons/95,890.6 liters. Since an airborne tanker can do two things with the fuel, burn it or off-load it to another aircraft, there is a tradeoff between the range and endurance of the tanker on the one hand and the amount of fuel available for off load. For example, with 120,000 lb./54,545 kg. of transfer fuel, the range of the KC-135R is 1,150 nm./2,090.1 km. On the other hand, with 24,000 lb./10,909.1 kg. of transfer fuel, the range is 3,450 nm./6,309.4 km.

  So, how does all of this come together in the real world of combat operations? In an intervention scenario, a KC-135R tanker can either deploy to an overseas base (carrying high-priority personnel and cargo), or support the deployment of other aircraft by tanking them—it can’t do both. This means that planners have to be careful to make sure that enough tankers are available to do both. Unfortunately, this is getting tougher all the time. During 1994, the tanker force took a 25% personnel cut and moved almost three quarters of its U.S.-based tankers and people from former SAC bases to three main AMC bases, as well as reassigning many aircraft to USAF Reserve and Air National Guard units. Tankers also are increasingly used to transport cargo, because metal fatigue and other problems with the C-141B Starlifter fleet have forced planners to assign cargo missions to the hard-working tankers.

  As long as combat aircraft need to burn fuel, there will be a requirement for tankers. Eventually the KC-135s and the force of about sixty wide-body KC-10 Extenders will have to be replaced. To some extent, the tanker mission can be performed by tactical aircraft fitted with extra fuel tanks and refueling gear mounted in removable “buddy packs.” But for really long hauls, there is no substitute for specialized and dedicated aerial tankers, based on economical, standardized commercial airframes. Just what that replacement will be exactly is anyone’s guess, but rest assured that when fuel is low and tensions are running high, the tanker crews will be the most popular folks in the skies.

  BOEING E-3C SENTRY AIRBORNE WARNING AND CONTROL SYSTEM

  Ever since our simian ancestors learned to climb trees, we have known instinctively that the higher you climb, the farther you can see. Later, many ancient cultures devoted considerable labor to building hilltop watchtowers. Spotting an approaching enemy even a few minutes sooner can make the critical difference between victory and defeat. The development of radar in the 1930s provided proof that nature is consistent. Generally speaking, radar works much like light—it travels in straight lines and usually cannot bend to peer over the local horizon. While a mountaintop is a good spot for a radar station, a mountain is rarely located where you need it, and it’s hard to move. However, if you could put a big radar antenna on a high-flying airplane, your radar horizon could theoretically reach out to two or three hundred miles. Also, if you put an air battle control staff on the same airplane and provide them with powerful computers, situation displays, and secure communications, you have what is called an Airborne Warning and Control System (AWACS)—the king on the chessboard of the modern air battle. Its status also makes it the most prized target in the sky, making the Sentry the sort of high-value airborne asset that will normally be protected by a hefty escort of fighters.

  AWACS aircraft had their start at the end of World War II, when the U.S. Navy was desperately trying to fight off the hordes of Japanese Kamikaze suicide aircraft that were trying to stop the invasion and battle fleets of the Americans. The Navy’s solution to the relative vulnerability of their surface ships was to convert TBM Avenger torpedo bombers into primitive AWACS aircraft. These early AWACS aircraft would have been available for the invasion of Japan in late 1945, had it taken place. Later, purpose-built AWACS aircraft were built by both the Air Force and Navy to their specific needs, usually on transport or airliner airframes. For many years, the USAF birds were based upon the classic Lockheed C-121 Super Constellation airliner /transport. Called the EC-121 Warning Star, it served in the AWACS mission for over twenty years before being replaced by the current AWACS aircraft, the E-3 Sentry, in the later 1970s.

  The Boeing E-3C Sentry AWACS looks like a large jet airliner being attacked by a small flying saucer. The airliner is the old reliable Boeing 707- 320B airframe, with a flight deck crew of four (pilot, copilot, navigator, and flight engineer) and a “mission crew” of thirteen to eighteen controllers, supervisors, and technicians back in the main cabin. Using an airframe similar to the venerable KC-135 and all the other Boeing Model 320 derivatives has proven quite popular with the U.S. military, and quite practical for the taxpayers. The saucer, or “rotodome,” is 30 feet/9.1 meters in diameter, 6 feet/1.8 meters thick at the center, and is supported 11 feet/3.35 meters above the fuselage on two streamlined struts just aft of the trailing edge of the wings. It is designed to generate enough aerodynamic lift to support itself, and does not place any stress, other than drag, on the wings or airframe. Mounted back-to-back with the main APY-2 radar antenna (upgraded from the original APY-1 version) inside the rotodome is an antenna array for the APX-103 IFF/ Tactical Digital Data Link (IFF/TADIL-C) system. This is a highly sophisticated IFF system, capable of interrogating virtually any IFF transponder in the world within 200 nm./365.7 km. (It reportedly has some sort of NCTR capabilities as well.) When transmitting, the rotodome, powered by hydraulic motors, makes one complete revolution every ten seconds. When it is not transmitting, it makes one revolution every four minutes, to keep the bearings lubricated. Considering the flight stresses it has to support and the complex of wave guides, power cables, and signal lines that must pass through it, the saucer’s rotary slip joint is a marvel of mechanical engineering. The radar transmitters and their elaborate power supplies and cooling equipment are located under the floor of the aft cabin, where conventional 707s stow the passengers’ luggage.

  All of this is packaged inside a standard Boeing Model 707-320B/VC-137 airframe with four Pratt & Whitney JT3D/TF33 turbofan engines. It is also quite expensive, having originally cost something like $270 million a copy.

  Getting into an E-3 is roughly the same as a KC-135, through a normal passenger hatch on the left side of the aircraft, where the cargo door is on the tanker. The first thing that strikes you is that the interior is much more comfortably appointed than the -135s. The interior is covered with the same kinds of sound-deadening wal
ls as a conventional airliner, mainly to ensure the comfort of the mission crew. Along with all the display consoles and other electronic gear, they are crammed into the cabin for missions that can last most of a day (though twelve to sixteen hours is normal). The tops of all the consoles in the main cabin are covered with blue indoor/outdoor carpet, which is actually quite nice to lean on! The flight deck is roughly similar to that of the Stratotanker, though some of the controls and displays are a bit more modern than the 1960s-vintage instruments on the -135.

  As you move back through the main cabin, there are any number of large cabinets and consoles scattered throughout, which can make moving about somewhat tight. These include the main computers for the radar system, as well as the symbology/display generator systems for the controller consoles. Towards the mid-cabin area over the wings are the radar control consoles. There are fourteen of these in back-to-back rows, with a flight seat (complete with shoulder harnesses and seat belts) in front of each position. Each console is configurable by the user, and can be set up for a controller, supervisor, or mission commander. Everyone is linked by a thirteen-channel intercom system, which feeds into a bank of secure Have Quick II radios, as well as other sets capable of UHF, VHF, and HF communications. In addition, the E-3 is equipped with a JTIDS data link terminal, which does much to reduce the burden on the radio channels.

  A cutaway drawing of he Boeing E-3B/C Sentry Airborne Warning and Control System (AWACS).

  Jack Ryan Entreprises, Ltd, by Laura Alpher

  Obviously, the primary reason for this aircraft’s existence is the radar system it is designed to carry. The original AWACS radar system, designated APY-1, was designed by Westinghouse after a 1972 competition with Hughes. The AWACS radar operates in the E/F band, meaning that it generates radar waves in the 2-to-4-Gigahertz (GHz) range, with a wavelength of from 7.5 to 15 cm./2.95 to 5.9 in. The radar uses the pulse-Doppler principle, relying on precise measurement of the tiny frequency shift in energy reflected from a moving target to distinguish flying aircraft from background ground clutter. This gives the radar the ability to “look down” and detect low-flying targets, as long as they are moving faster than 80 knots/148 kph.

  The normal E-3 mission crew consists of separate surveillance and control sections, each typically commanded by a senior captain. In the surveillance section, three to five technicians monitor the air traffic in a huge volume of airspace and pass on information to the control section. This is composed of two to five weapons controllers sitting at multi-purpose consoles, guiding friendly aircraft to intercept enemy or unidentified contacts. Depending on its particular mission, an AWACS also may carry senior staff officers, radar technicians, radio operators, a communications technician, and a computer technician.

  While the E-3 displays are a great improvement over the “bogey dope” screens of the old EC-121s, which required almost mystical powers to interpret, they are rapidly becoming dated. The symbology is somewhat hard to interpret, and the screens can easily become cluttered. On the positive side, the trackball “mouse” used to select or “hook” targets on the screens is quite easy to use, and once you get used to the idea that a small symbol with a track number is an aircraft, you do quite well.

  Aft from the console area are more electronics cabinets, as well as an area reserved for passengers and off-duty personnel. While the seats are not terribly comfortable, they are an improvement over the maximum-stress environment of being “on the scope.” There is also a tiny galley, as well as several small bunks which are usually reserved for spare flight crew personnel (pilots, navigators, etc.). Combat AWACS missions in excess of eighteen hours during Desert Storm were not uncommon, and spare personnel were often necessary. At the very back of the cabin is a rack of parachutes, and there’s a bail-out door in the floor of the forward cabin. This, fortunately, has never had to be used, since no E-3 Sentry has ever been lost.

  A USAF Boeing E-3 Sentry Airborne Warning and Control System (AWACS) aircraft arrives in Saudi Arabia during Operation Desert Shield. Fourteen of these valuable aircraft, as well as E-3s from the Royal Saudi Air Force and NATO, provided airborne radar support during Desert Shield and Desert Storm. Official U.S. Air Force Photo by Jim Curtis

  The key to making this system work is the need for steady, consistent flying. Sentry pilots are trained to fly a precise, wide oval racetrack course, straight and level, avoiding any sharp banking turns that might disrupt the radar beam’s normal sweep. Typical cruising altitude for an operation mission is 29,000 feet/8,840 meters ( just about the height of Mt. Everest), at a maximum cruising speed of 443 knots/510 mph./860 kph. Unrefueled, the E-3 has an endurance of more than eleven hours, and the aircraft has a receptacle for in-flight refueling which can stretch the endurance to twenty-two hours, a limit set by the supply of lube oil for the four JT3D/ TF33 engines. On these marathon aerial-surveillance missions, the endurance of both the flight crews and mission personnel is stretched to the limit. This has been pointed to as one of the weaknesses of the AWACS community. In the past, there have frequently been difficulties with flight personnel getting adequate rest between missions, as well as with the excessive number of “on-the-road” days that have been a hallmark of the AWACS lifestyle for almost twenty years. Unfortunately, since AWACS aircraft are a favorite instrument of politicians trying to find out what’s happening in a trouble spot, the lifestyle of the AWACS crews is unlikely to change much.

  The interior of a USAF Boeing E-3 Sentry AWACS aircraft looking aft. Visible are the consoles, where the controllers sort out airborne contacts and supervise flight operations.

  Boeing Aerospace

  Most of the thirty-four E-3s in USAF service are assigned to three operational Airborne Air Control squadrons (the 963rd, 964th, and 965th), and one training squadron (the 966th) of the 552nd Air Control Wing based at Tinker AFB, Oklahoma. One aircraft is assigned to continuing research and development work at the Boeing plant in Seattle, and a few are permanently stationed in Alaska, assigned to the Pacific Air Force (PACAF) commander. Detachments have been, and continue to be, deployed to trouble spots all over the world. These started with a movement by the Administration of President Jimmy Carter of a three-aircraft detachment of E-3s to Saudi Arabia to keep an eye on the Iran/Iraq War. It was called ELF-1, and what was planned as a deployment of several months eventually wound up lasting over eleven years. It seems to be the lot of the AWACS community to spend their lives on the road, keeping watch on the world’s trouble spots.

  Even though some of the E-3’s systems are getting to be a bit dated right now, the E-3s of the AWACS fleet are the crown jewels of the USAF fleet, and represent the most valuable aircraft that an aerial commander can be assigned. Their presence on the aerial battlefield greatly improves the efficiency of any force that they support, thus explaining why USAF leaders call the AWACS fleet a “force multiplier.” This may explain the tolerance for the high costs of developing, operating, and maintaining such a force. The technical problems of developing a reliable and effective airborne warning and control system are so great that only one other nation has ever really managed it—Russia, with its A-50 Mainstay AWACS, based on an IL-76 heavy transport airframe. Meanwhile, NATO, Saudi Arabia, and a few other very friendly nations have bought versions of the E-3.

  As the E-3 fleet heads into its twentieth year of service, there are strong plans to upgrade the system so that it will be ready to continue its valuable service into the 21st century. The major points of the planned E-3 upgrade program include:• GPS—It has taken a while, but the E-3 is finally going to get a GPS receiver to help improve both navigational accuracy of the AWACS aircraft itself, as well as the quality of the information it supplies.

  • Radar System Improvement Program (RSIP)—The RSIP upgrade is a long-overdue series of improvements to the APY-1/2 radar systems that includes an improved radar computer, a more modern graphics processor for the radar operators’ consoles, as well as upgrades to the radar system itself. All of these should
allow the AWACS controllers to handle more targets with less clutter on the displays. In addition, the software rewrite that is included with RSIP will allow for things like “windowing” (display-within-a-display) capabilities, as well as the ability to detect low-observable/first-generation stealth aircraft. While the technology behind this last capability is highly classified, it probably centers around the same kind of “broad band” processing technology that is used on submarines. Westinghouse is the prime contractor on the RSIP upgrade, and will begin installation in the late 1990s.

  As the E-3 completes its second decade of service, it is time for the Air Force to start thinking about a Sentry replacement. The problem, of course, is finding the money, as well as deciding what kind of aircraft the USAF wants to base it on. As with the other models of first-generation American jet transports, the 707 was designed to very conservative 1950s engineering standards; and after forty years of steadily advancing technology, it’s too heavy, it’s a fuel hog, and it’s too hard to update with modern digital flight control systems. When Japan decided to join the AWACS club, the Japanese ordered the basic E-3 mission package on a modern airframe, the wide-body, twin-turbofan Boeing 767. With a two-person flight crew and better fuel economy, operational costs should be lower, but this is still going to be a very costly aircraft.