What should pilots do if unsure about an ATC instruction?

• A. Take a best guess and proceed.
• B. Ask for clarification or say 'say again.'
• C. Ignore and proceed
• D. Contact another frequency.

Answer: (B)

When you’re unsure about an ATC instruction, you must not guess or proceed without clarification. The safest and most effective move is to ask for clarification using standard phraseology, such as “say again.” This prompts the controller to repeat or restate the instruction so you and the controller share the exact understanding of what is expected. This reduces the risk of misreading an altitude, heading, speed, or complex clearance and helps maintain proper separation from other traffic.

Why this is the best approach: it preserves safety by ensuring you execute exactly what ATC intends, even in noisy or high-workload environments where instructions can be misunderstood or garbled. It also demonstrates good cockpit discipline—prioritizing clear communication over speed of action.

Why the other options aren’t appropriate: taking a best guess can lead to wrong actions that conflict with other traffic or airspace rules; ignoring the instruction and proceeding is unsafe and noncompliant; contacting another frequency would not resolve the misunderstanding and could cause further confusion or delays.