This is the second half of a 2-part post on air refueling the Lockheed C-5. Part 1 of Air Refueling the Lockheed C-5 may be found here.
Air Refueling the C-5, Moving In
We left off with the receiver in the pre-contact position with both aircraft ready to conduct air refueling. At this point, the boom operator is looking at something like this.You can see the air refueling receptacle just aft of the cockpit with the white lead-in strips to help the boom operator. The refueling door is open.
There is a centerline stripe painted on the bottom of the tanker to help with alignment as you move into the contact position. The boom operator “flies” the boom with the two wings shown in the photo, moving it left or right and up and down through an arc. The inner portion of boom telescopes out to press into the refueling receptacle.
The bottom of the tanker has two rows of indicator lights, one on either side of the centerline stripe. In the photos they look like dark bars. These lights provide an indication of the receiver position with respect to the ideal refueling position. There is a “box” of airspace that the receiver must remain within. The box dimensions are determined by the lateral and vertical limits of movement of the refueling boom and the limits of the extension and retraction of the inner portion of the boom. If you are the refueling pilot and sitting in the left seat it is easy to think of the left row of indicator lights being controlled by your left hand (the yolk moving the aircraft up or down) and the right row of lights being controlled by your right hand (throttle moving the aircraft forward or aft). This is not completely true, of course, because the arc movement of the boom means a movement forward will not only compress the boom, but cause it to move downward in the arc. It is a good generalization, though. As I remember, each end of the light bar (forward and aft) has a red light, meaning you are nearing a disconnect. Then there are three or four amber lights on each side of a center green light. The center of the refueling envelope is attained when you have two green lights illuminated, one on each set of lights. Until the boom is latched into the refueling receptacle, the indicator lights are manually controlled by the boom operator.