Which transmission confirms approval to cross Runway 21R?

• A. Copy that, proceed now.
• B. Crossing not permitted.
• C. Airfield3, Nellis Tower, approved to cross Runway 21R at Taxiway Delta, report when off.
• D. Runway closed.

Answer: (C)

Explicit ATC clearance is required to cross a runway. The correct transmission is the one that gives you a definite approval from the controller, specifies exactly where you’ll cross, and tells you to report when you’re off. In this case, the message from Nellis Tower stating you’re approved to cross Runway 21R at Taxiway Delta and to report when off confirms both the crossing permission and the exact crossing location, plus the acknowledgment that you’ll inform them once you’ve cleared the runway. This is the only transmission that provides a real crossing clearance with the necessary details.

The other options either imply permission to proceed without the needed specificity, deny permission, or state the runway is closed, none of which meets the requirement for a formal cross-runway clearance.