When a trucking company has an oversized load (too heavy or too wide), a pilot car service is employed. These folks help keep not only the haul safe, but also keep all other drivers on the road aware of the cargo for their own safety. Pilot cars can also be employed to escort important vehicles, like those of a high government official.
The escorted car or truck will often have signs indicating that it is special in some way. If the pilot is leading a motorcade, the vehicle in question will most likely have flags indicating who they are and their nationality. For example, presidential motorcades will have the American flag on the cars. Orange warning flags and banners indicating size, like wide load, will be present on oversized equipment being transported, mainly so they can be more visible to other automobiles. With truck loads, it is up to the pilot to be aware of these flags and make sure they remain attached to the trailer, pole, or tow since the driver cannot seem them.
Pilots are usually accompanied with CB radios so there is always a constant line of communication between the vehicles and dispatch service. This helps both drivers as one can notify the other of any dangers up ahead, to the side, or behind each other. The radios also allow the dispatch to be updated on travel times, fuel stops, rest stops, and potential accidents that may occur. The radio allows the pilot to be the eyes and ears for the trucker and dispatch in almost any situation.