Definition
A transparent display mounted in the pilot's forward line of sight that projects flight information — such as airspeed, altitude, attitude, heading, and flight path — onto a combiner glass, allowing the pilot to read instrument data without looking down at the panel.
Plain English
A see-through screen in front of the pilot's eyes that shows key flight numbers and symbols, so the pilot can keep looking out the windshield while still reading the instruments.
Context Anchor
Seen in instrument approach procedure notes and in inoperative equipment tables when a procedure depends on the HUD being available.
Derivation
From the literal idea of keeping your head up — looking outside — instead of head-down, looking at the panel. The display is positioned so the pilot can read flight data without lowering their gaze.
Why Pilots Care
It reduces the time a pilot spends looking down at instruments, which is especially important for maintaining situational awareness during critical phases like instrument approaches.
Intuition Check
“Heads-up” does not mean a warning here. It means the display is positioned so the pilot can keep looking forward while seeing flight information.
Example Sentence 1
On final approach the captain kept his eyes outside, reading airspeed and glidepath cues directly off the HUD.
Example Sentence 2
With the HUD inoperative, the pilot had to rely on the traditional instrument panel for the approach.