Definition
A head-down display (HDD) is a flight information display mounted in the instrument panel, requiring the pilot to look down into the cockpit to read flight data such as attitude, airspeed, altitude, heading, and navigation information. It is the conventional panel-mounted display, contrasted with a head-up display (HUD) which projects the same information onto a transparent surface in the pilot's forward line of sight.
Plain English
The regular instruments and screens built into the dashboard of the aircraft. To read them, the pilot has to look down from the windshield into the cockpit.
Context Anchor
Seen in discussions of head-up displays, instrument panels, and how pilots divide attention between the outside view and cockpit instruments.
Derivation
Named for the physical action required to use it: the pilot's head goes down to look at the panel. The term exists mainly to distinguish it from head-up displays, which were developed later.
Why Pilots Care
Extended time spent looking down reduces outside scan for traffic, terrain, and runway alignment, increasing workload during critical phases of flight.
Intuition Check
“Head-down” does not mean the pilot must literally lower their head for a long time. It means the information is not in the forward outside view, so the pilot has to look inside the cockpit to read it.
Example Sentence 1
On approach in low visibility, the pilot relied on the head-down display to monitor altitude and airspeed while the HUD presented the flight path symbol on the windshield.
Example Sentence 2
During the missed approach the crew cross-checked the head-down display for missed approach point timing while maintaining instrument scan.