Definition
A see-through display surface, mounted in the pilot's forward field of view, onto which flight information is projected so the pilot can read the data while continuing to look outside the aircraft. In a Head-Up Display (HUD), the transparent screen is the combiner glass that overlays symbology on the outside view without blocking it.
Plain English
A clear panel in front of the pilot that shows flight information without hiding what's outside the windshield. You can read the numbers and look through the glass at the same time.
Context Anchor
Seen in head-up display descriptions, where flight information is placed in the pilot’s forward view instead of only on the instrument panel.
Derivation
Transparent comes from the Latin trans- (through) and parere (to appear) -- literally 'something you can see through.' Screen here means a surface that displays an image. Together: a display surface you can see through.
Why Pilots Care
Keeps essential flight data visible while maintaining continuous visual contact with the runway, terrain, or traffic.
Analogy
It is similar to useful information appearing on a car windshield, except in an aircraft it is designed and aligned for flight use.
Intuition Check
Do not think of this as a normal opaque computer screen. In this context, the screen is clear enough to see through while it also shows information.
Example Sentence 1
The HUD projects airspeed and altitude onto a transparent screen positioned just below the pilot's normal line of sight.
Example Sentence 2
In instrument conditions the transparent screen displayed heading and altitude without requiring the pilot to look down at the panel.