Many sources of accidents on the flight line are involved with propellers and rotor blades. They are difficult to see when they are turning, and personnel sometimes become distracted and forget about the danger. The main difference between these, and other flight-line accidents, is that they are almost always fatal.
Most blades have high-visibility markings, to ensure that they can be seen when they are turning. These markings vary from a yellow blade tip marking, to black and white alternate stripes along the full blade length.
To reduce the risk of propeller and rotor blade strikes, it is best to follow strict rules as to the correct way to approach and leave the vicinity of an aircraft or helicopter whilst it is under power. For example (and allowing for the fact that there are specific rules laid down for each aircraft), installing and removing chocks should normally be done from the wing-tip direction. Boarding and leaving a helicopter should always be done from the side.
When dealing with running jet engines there are similar dangers. These come not only from the noise risk, which can result in deafness, but also from the risk of intake suction, which has resulted in ramp personnel being sucked into the engine and being killed. At the rear of the aircraft, there is the risk of jet blast, which, at maximum thrust is quite capable of overturning a vehicle if it passes too close behind the aircraft. Piston-powered aircraft (depending on their size) will have similar danger areas.
