Definition 1 of 2
Definition
A message sent by an Air Route Traffic Control Center (ARTCC) flight data unit to inform an adjacent ARTCC and/or terminal facility that a flight has been cleared along a route other than the previously coordinated preferred route, or along a preferred route that begins at a fix not normally used for that route.
Plain English
A heads-up message between ATC facilities saying, 'this flight isn't on the usual route we agreed on, or it's joining the usual route at an unusual place.' It lets the next facility know what to expect before the aircraft arrives.
Context Anchor
A pilot usually encounters the result of this notice as an amended clearance or route change, not as the internal notification itself.
Why Pilots Care
Using the notified route reduces the chance of a last-minute reroute, holding, or conflict with other traffic.
Intuition Check
“Preferred” does not mean the pilot’s favorite route here. It means a route air traffic control has established or commonly uses for managing traffic.
Example Sentence 1
When the controller cleared the flight off the published preferred route, the center generated an ATC Preferred Route Notification to the next facility along the way.
Example Sentence 2
ATC issued an updated Preferred Route Notification due to temporary airspace restrictions.