The combat controller training program is as follows: Combat Control Screening Course, Lackland Air Force Base, Texas This 10-day screening course focuses on physical fitness with classes in sports physiology, nutrition, basic exercises, CCT history and fundamentals. Combat Control Operator Course, Keesler AFB, Miss.
Static or dynamic friction always act in a direction opposite to the impressed force. The dynamic friction does not need in any force. It is realy directed in opposit to the velosity. And the static friction can never be without the shearing force and it is always directed in opposit to it. However, you are right - dynamic friction forces can or slow down the movement of the body or accelerate it.
Relative to the person pushing the box the frictional force is opposite to direction of travel but relative to a person standing next to the train the frictional force is the same direction as the box is travelling. Since motion is relative then yes friction can point in the direction of motion. This would only work if the thing that is causing the friction is moving in the opposite direction to the force pushing the object. An example is a person pushing a heavy box from the front to the rear of a fast moving train.