Which of the following methods for approaching a running rescue helicopter is most dangerous?

Approaching a running rescue helicopter from the rear while remaining in an upright position presents significant dangers due to the risk of rotor wash and how the helicopter's rotors operate. When approaching a helicopter, it is crucial to be aware of the rotor blades, which can be almost invisible in certain situations due to their speed. By remaining upright and approaching from the rear, an individual may inadvertently enter into the rotor's downwash area, which can create turbulent air that can affect their balance and orientation. Additionally, if one is too close behind the helicopter, they may not be able to see or hear the blades effectively, increasing the risk of an accident.

In contrast, other methods of approach, such as crouching or moving slowly from the front, allow for better visibility of the rotor blades and a more stable approach, reducing the likelihood of injury. Running towards the helicopter is also dangerous as it may lead to a loss of control or awareness of the surroundings, but approaching from the rear while upright is particularly hazardous due to the dual risks presented by the rotor's operational dynamics.