Definition
A reference line displayed on an ARTS III or DBRITE radar scope that shows controllers the correct downwind track aircraft should follow when being sequenced into the traffic pattern for a given runway.
Plain English
A line drawn on the controller's radar screen that shows where airplanes flying downwind should be in order to line up properly for landing.
Context Anchor
Seen in diagrams of ARTS III or DBRITE radar displays used by air traffic controllers near airports.
Derivation
Downwind' refers to the leg of the traffic pattern flown parallel to the runway in the opposite direction of landing. 'Alignment guide' simply means a visual line used to keep things lined up. Together, it is a line on the scope that helps the controller keep downwind traffic properly aligned.
Why Pilots Care
Controllers use this guide to issue vectors and spacing instructions. Knowing it exists helps pilots understand why ATC may ask them to adjust heading or position when on the downwind leg.
Intuition Check
Do not read this as a cockpit guide for the pilot. Here, “guide” means a reference line on the controller’s radar display, and “downwind” means the airport traffic path, not simply any direction the wind is blowing toward.
Example Sentence 1
The controller used the downwind alignment guide on the DBRITE display to vector the inbound traffic onto a proper downwind leg for Runway 27.
Example Sentence 2
On the DBRITE display the downwind alignment guide helped the controller maintain proper spacing between two aircraft on the downwind leg.