I'm sitting behind the pilot of Defense Secretary Donald Rumsfeld's E-4B aircraft, a highly customized and heavily armored version of the Boeing 747. It's a flying command center filled with all sorts of sophisticated electronic equipment. We're about 25,000 feet above Alaska on a 15½ hour, nonstop flight from Andrews Air Force Base outside Washington to Beijing.
The plane's four jet engines have been gulping fuel since we left Washington 7½ hours ago and they are thirsty -- very thirsty.
Up ahead, just off to the right are three KC-135 tanker jets -- versions of the Boeing 707-- each with about 90,000 pounds of jet fuel -- an airborne filling station.
The pilots of all four aircraft and the boom operators on each of the tankers are about to begin an intricate, high-speed, high-altitude ballet, the sort of maneuver that allows fighter jets and bombers around the world to fly long distances without landing to refuel, greatly increasing the range of American firepower.
The tankers are flying in formation, their altitudes separated by about 500 feet each. In a process that will be repeated three times over the next hour, the pilot of the E-4B turns off the automatic pilot and, coordinating the flight controls and the throttles of the four engines, manually maneuvers the big plane underneath the first tanker.
If you think that already sounds complicated, consider this: As the planes near each other, the wake of the tanker is pushing our plane down. And the air flow around our aircraft is pushing the tanker up.
No more than 12 feet above and just ahead of us, an operator in the tail of the tanker uses a joystick to lowered the fueling boom from the rear of the tanker. The pilot of the E-4B uses a remote control to flip open the filling door on the nose of the plane. The boom operator guides the boom into the filling tube.
They connect on the first try with a satisfying "thwuck." Another pilot explains to me that it isn't always that easy. Sometimes bad weather can make maneuvering tricky. Sometimes a tired pilot or boom operator may need a couple of tries.
The fuel starts flowing from the tanker to our plane. As it does, the tanker gets lighter, wants to fly higher and faster and becomes more responsive to changes in the flight controls and engine throttles. And our plane, filling with fuel, gets heavier, wants to fly lower and slower and becomes more sluggish.
Plus, during the first refueling operation, there's another complication: The tanker's boom has a bad seal, so jet fuel is spraying onto the E-4B's windscreen like a heavy rain. The wipers are pumping furiously, but visibility is badly reduced.
The E-4B's pilot and first officer are both concentrating on keeping the two planes in the right position, moving the flight controls and engine throttles. The tanker is on automatic pilot, so it's a smooth ride for its crew. The pilots of the plane being refueled must react to the tanker's movements, their hands, arms, legs and feet in constant motion.
"It's what we train for," another pilot says in his best "Top Gun" nonchalance. For each refueling operation, the plane is commanded by a different pilot.
Once, during the first refueling, there was an accidental disconnection, as the plane and boom separated. The E-4B's pilot simply pulled it back closer to the tanker and the tanker's boom operator rethreaded the boom into the refueling neck.
The result can be a rather bumpy ride, a bit like riding the waves on a choppy sea. The pilots call it "dolphining," and describe by arcing a hand up and down like a dolphin playing in the waves.
Down below, some of my colleagues tell me they got a little seasick. But in the cockpit, it doesn't bother me -- I suppose it's because I can see the movements of the tanker and the far horizon.
After about 20 minutes or so, the tanker is dry. The E-4B's pilots slow down a drop a bit to pull away from the empty KC-135 before climbing and veering slightly to the right to pull up beneath the second tanker and do it all over again.
Topping off at 25,000 feet -- all in a day's work.