Miles-in-trail describes which aspect of traffic spacing?

• A. Describes the time interval between aircraft
• B. Describes the distance to maintain behind another aircraft
• C. Describes the number of miles required between aircraft
• D. Describes the difference in speed between aircraft

Answer: (C)

Miles-in-trail is a measure of the separation between aircraft expressed in miles along the same route and level. It tells you exactly how many miles should separate you from the aircraft ahead, making it a distance-based spacing standard expressed in miles. It’s not about how long the spacing lasts (time interval) or about differences in speed, and while maintaining a safe distance behind another aircraft is related, miles-in-trail specifically quantifies that separation in miles.