A pace truck drives in front of a 413th Flight Test Squadron UH-1 Huey during an azimuth test Nov. 23 at Eglin Air Force Base, Fla. The pace truck simulates a hover reference point while moving with the helicopter. This creates an artificial cross wind in respect to the helicopter. This process continues by changing the direction of the helicopter to cause that wind to reach a different portion of the aircraft to determine at what point the helicopter becomes difficult to handle. (U.S. Air Force photo/Samuel King Jr.)