What is clearance void time?

• A. A boundary between two air masses where cold air is replacing warm air.
• B. A low-power, low- or medium-frequency beacon installed at the site of the outer or middle marker of an ILS.
• C. Used by ATC, the time at which the departure clearance is automatically canceled if takeoff has not been made. The pilot must obtain a new clearance or cancel the IFR flight plan if not off by the specified time.
• D. A small circle graduated in 360° increments, to show direction expressed in degrees.

Answer: (C)

Clearance void time is the time stated in a departure clearance by which the takeoff must occur; if you are not off the ground by that moment, the clearance is void and you must either obtain a new clearance or cancel IFR. This ensures ATC isn’t holding a clearance indefinitely for a flight that hasn’t started, and it gives the pilot a clear authority to re-clear or cancel the flight plan if nothing has begun. For example, if departure clearance is issued with a void time of 10:05 and you’re still on the ground at 10:06, you must contact ATC to obtain a new clearance or cancel IFR before continuing. The other options describe a weather boundary, a marker beacon, or a navigation instrument, which are unrelated to how departure clearances are managed.