What does a solid yellow line on a runway signify?

• A. Mandatory instruction
• B. Area for stopping
• C. Area for crossing
• D. Unavailable for use

Answer: (D)

A solid yellow line on a runway is used to indicate that the area is not available for use. This marking serves as a visual cue for pilots and ground controllers, signaling that the section of the runway is restricted from aircraft operations. It is crucial for ensuring safety and preventing aircraft from entering areas where they might conflict with other traffic or where operations are not allowed. This marking helps in guiding pilots to stay within the operational zones of the airport and avoid accidents.

The other options do not accurately reflect the purpose of a solid yellow line. A mandatory instruction would be typically indicated with a solid red line, while areas designated for stopping or crossing tend to have different markings or lights that communicate those specific functions.