What must you do if you encounter a stop sign on the airfield?

Answer: B — Stop completely before proceeding

When you encounter a stop sign on the airfield, stopping completely before proceeding is the correct action. This requirement is in place to ensure safety and maintain orderly traffic flow on the airfield, which can be a high-risk environment due to the presence of aircraft, vehicles, and personnel. A complete stop allows you to check for any oncoming traffic or hazards that may not be immediately visible, such as another vehicle approaching from a blind spot or an aircraft taxiing. By adhering to this rule, you contribute to the overall safety protocols established for maintaining situational awareness and preventing accidents on the airfield. Engaging in any action that involves reducing speed without fully stopping, ignoring the sign due to perceived absence of others, or only stopping based on the presence of other vehicles compromises safety protocols and increases the risk of incidents. Following the guideline of halting completely ensures all drivers exercise caution and are proactive rather than reactive to potential dangers.