What action is advisable if you encounter a sudden obstacle while driving a commercial vehicle?

Maintaining control and braking gradually is the safest and most advisable action when encountering a sudden obstacle while driving a commercial vehicle. This approach allows the driver to reduce speed without losing control of the vehicle, which is crucial given the size and weight of commercial vehicles. Gradual braking enables the driver to assess the situation, observe what the obstacle is, and react appropriately, which may include altering the path if it's safe to do so.

In the context of commercial vehicle operation, the importance of stability and control cannot be overstated. Braking suddenly could cause a loss of traction, potentially leading to a rollover or a collision, especially in heavy or loaded vehicles. The key is to manage the vehicle's speed while maintaining a clear view of the obstacle and the surrounding traffic.

Other responses, such as accelerating to avoid an obstacle or steering sharply, can dangerously destabilize the vehicle. These maneuvers could lead to a loss of control or increase the risk of an accident. Using the horn, while it can be useful in providing warnings, does not address the immediate necessity of avoiding the obstacle safely and effectively.