Definition
A transparent display that projects flight information — such as airspeed, altitude, attitude, heading, and flight path — onto a combiner glass positioned in the pilot's forward line of sight, allowing the pilot to read instrument data while continuing to look outside the aircraft.
Plain English
A see-through screen mounted in front of the pilot that shows key flight numbers and symbols, so the pilot can keep looking out the windshield while still seeing what the instruments are telling them.
Context Anchor
Seen in aircraft with advanced cockpit displays, especially when discussing instrument information shown in the pilot’s forward view.
Derivation
Called 'head up' because the pilot keeps their head up and eyes forward, instead of looking 'head down' at the instrument panel. The name describes the posture the display is designed to support.
Why Pilots Care
It reduces the need to shift focus between instruments and the outside environment, improving safety and precision especially in low-visibility conditions.
Analogy
It is similar to a car that shows speed on the windshield, so the driver can see the road and the speed at the same time.
Intuition Check
Do not read “head up” as something worn on the pilot’s head. In this term, it means the information is placed where the pilot can see it while looking forward.
Example Sentence 1
On the approach into low fog, the captain flew the HUD all the way to the runway, calling visual just before touchdown.
Example Sentence 2
In IMC, the HUD projected the flight path vector directly in the pilot's view to assist with precise navigation.