What phraseology is used to authorize a vehicle to cross a runway?

• A. <Vehicle call sign> Cross Runway <number> when safe
• B. <Vehicle call sign>, Cross Runway <number> when safe
• C. Cross Runway <number> when safe, <Vehicle call sign>
• D. Cross Runway <number> now, <Vehicle call sign>

Answer: (B)

Here, the important idea is using proper runway-crossing authorization phraseology: address the specific vehicle by its call sign, then issue the crossing instruction with the runway number and a safety condition. Saying the call sign followed by a comma, then “Cross Runway when safe,” clearly directs the correct vehicle and makes the action conditional on safety. The comma helps separate the addressed party from the instruction, reducing ambiguity on a busy frequency. The phrase “when safe” is essential because it tells the driver to cross only when conditions are clear, coordinated with other traffic, and it avoids implying immediate action. Using the instruction before naming the vehicle, or replacing “when safe” with “now,” would create confusion or pressure to act without ensuring safety.