Which symbol indicates the aircraft is unsafe or unserviceable, or unknown status has been identified and the aircraft will not be flown until cleared?

• A. Red X
• B. Blue Circle
• C. Green Check
• D. Dash

Answer: (A)

The symbol that signals the aircraft is unsafe or unserviceable, or that unknown status has been identified and the aircraft will not be flown until cleared, is the red X. This mark is used in maintenance and flight-clearance documentation to convey an immediate halt to flight operations until the issue is resolved and proper clearance is given. It communicates unambiguously that the aircraft cannot be operated until it is inspected, repaired, and certified safe to fly. The other symbols do not carry this prohibitive meaning: a blue circle is not the designation for unserviceable status, a green check indicates serviceable or cleared for flight, and a dash typically denotes no data or not applicable.