Definition
A type of head-up display that uses a holographic optical element embedded in the combiner glass to project flight symbology into the pilot's forward field of view. The holographic film selectively reflects the specific wavelength of light produced by the HUD projector while allowing nearly all other light to pass through, so the symbology appears bright and sharp without significantly dimming the view of the outside world.
Plain English
A see-through cockpit display that uses a special coated glass to show flight information floating in front of the pilot's eyes, while still letting them see clearly through the windshield.
Context Anchor
Seen in HUD discussions, especially where the handbook explains how flight guidance can be shown in the pilot’s forward view.
Derivation
From the Greek 'holos' (whole) and 'graphe' (writing or drawing). A hologram records light in a way that reproduces a complete image. In a HUD, the holographic film is engineered to reflect only the projector's light, which is what makes the symbology visible while keeping the glass transparent.
Why Pilots Care
Reduces the need to look away from the runway or outside environment during critical phases of flight, improving situational awareness and safety on instrument approaches.
Analogy
Like having a clear dashboard floating in the windshield that shows your speed and path without blocking what you see ahead.
Intuition Check
Do not assume “holographic” means a 3-D movie image floating in the cockpit. Here it means a display that uses specially controlled light to place readable flight information in the pilot’s forward view.
Example Sentence 1
The aircraft's HUD uses a holographic display, so the airspeed and glideslope symbology stay crisp even with the approach lights visible through the combiner.
Example Sentence 2
During the low-visibility landing, holographic displays presented the localizer and glideslope cues without requiring a head-down scan.