During surface taxi, what does the collective pitch control?

The collective pitch control in a helicopter primarily manages the pitch angle of the rotor blades, which directly affects the amount of lift produced. During surface taxi, this control allows the pilot to adjust the rotor blades collectively to increase or decrease lift, thereby enabling the helicopter to rise off the ground or settle back down.

While the altitude can be influenced by the collective pitch during flight, during taxi, the primary focus is not on changing altitude but rather on maintaining a safe ground position and moving along the surface. Thus, the collective does affect how quickly the helicopter can move in a horizontal plane, which relates to the rate of speed when surface taxiing. It allows for controlled movement and can adjust the helicopter's lift as necessary for safe ground handling.

In this context, the option regarding rate of speed is the most relevant as collective pitch allows the pilot to manage not just lift but the overall dynamics of the helicopter as it moves on the ground, making it an essential component during surface operations.