Definition
A cockpit display design principle stating that information sources which must be mentally combined or compared by the pilot should be physically grouped close together, while unrelated information should be visually separated. The closeness of items on the display should match the closeness of the mental task that uses them.
Plain English
Things a pilot has to look at together should sit together on the panel. Things that have nothing to do with each other should be kept apart so they do not get mixed up.
Context Anchor
Seen in cockpit layout, instrument panel design, checklist design, and discussions of how pilots scan and use flight information.
Derivation
From 'proximity' (Latin proximitas, nearness) and 'compatibility' (how well things work together). The name reflects the idea that physical nearness on a display should be compatible with how the information is used in the pilot's head.
Why Pilots Care
It guides the layout of flight instruments and electronic displays to reduce pilot mental workload and lower the chance of missing critical information during flight.
Analogy
A kitchen stove is easier to use when each burner control is clearly near or aligned with the burner it operates. If the controls are scattered or too close without clear grouping, a person can turn the wrong one.
Intuition Check
Do not read “proximity” as simply “closer is always better.” In this principle, closeness should match how the pilot actually uses the items: related items near each other, unrelated or easily confused items separated.
Example Sentence 1
The new glass cockpit follows the proximity compatibility principle by placing airspeed, attitude, and altitude tapes side by side on the primary flight display.
Example Sentence 2
Applying the proximity compatibility principle to the engine instruments made it easier to monitor related parameters during a busy departure.