Without ASDE-X, do not clear an aircraft for a landing, the option, or low approach on the same runway of an aircraft in LUAW status or taxing into position until __________.

• A. the aircraft has exited the runway
• B. the aircraft is five miles final
• C. the aircraft has exited the runway or starts takeoff roll
• D. the taxiing aircraft has cleared the runway

Answer: (C)

The situation tests safe runway use when another aircraft is occupying or about to use the same runway, and you lack automatic surface surveillance. Without ASDE-X, you must confirm the active runway is no longer in use by the other aircraft before you clear another aircraft to land or perform a low approach if there’s an aircraft on the runway in LUAW (Line Up and Wait) or taxiing into position. The runway is considered unavailable until that preceding aircraft either leaves the runway or begins its takeoff roll. Exiting the runway means the path is free, and starting takeoff roll means the runway is actively being used for a departure, both situations that release the runway for the next arrival. Waiting for five miles final doesn’t guarantee the runway is clear, and simply saying the taxiing aircraft has cleared the runway may not cover the moment when a departure is about to begin; the important trigger is either off the runway or in takeoff motion.