Definition
A small digital readout on the Horizontal Situation Indicator (HSI) or Primary Flight Display (PFD) that shows, in numerical form, the heading the pilot has dialed in using the heading bug. It confirms the exact target heading currently selected for reference or for use by the autopilot's heading mode.
Plain English
A small number on the display that tells you exactly which heading you have set as your target. It matches the position of the heading bug, but shows it as digits so you can read it precisely.
Context Anchor
Seen on instrument flight displays, navigation displays, and training diagrams that show selected heading information.
Derivation
“Heading” comes from the idea of the direction the aircraft’s nose, or head, is pointing. “Box” here means a marked area on a display, not a physical container.
Why Pilots Care
It lets the pilot command a precise turn and maintain a desired heading without continuous manual control, improving accuracy and reducing workload in instrument conditions.
Intuition Check
Do not read the selected heading box as the aircraft’s current heading. It shows the heading that has been set or selected; the airplane may still be turning toward it.
Example Sentence 1
After being cleared to turn left to 180, the pilot rotated the heading knob until the selected heading box read 180 and engaged the autopilot's heading mode.
Example Sentence 2
With the autopilot coupled, the aircraft rolled out on the heading shown in the selected heading box.