Definition
Standardized placards installed on and around airport movement areas that convey mandatory instructions, location information, direction guidance, destination guidance, or operational information to pilots taxiing on the airport surface. Airport signs use defined color schemes — red signs with white inscriptions denote mandatory instructions (such as runway holding positions), yellow signs with black inscriptions indicate location, direction, or destination, and black signs with yellow inscriptions identify the taxiway the aircraft is currently on.
Plain English
The painted boards posted along taxiways and near runways that tell a pilot where they are, where they can go, where they must stop, and what they need to know while moving on the ground.
Context Anchor
Seen while taxiing on the airport, approaching a runway, leaving a runway, or following instructions from air traffic control on the ground.
Derivation
Sign comes from the Latin word signum, meaning a mark, signal, or token. That origin fits the airport use: a sign is a visible mark that carries information the pilot must understand and act on.
Why Pilots Care
Misreading a sign can cause a pilot to enter the wrong area or runway, creating a safety hazard during ground movement.
Intuition Check
Do not treat airport signs as background labels or decoration. In airport operations, signs are practical guidance and warnings that help control where aircraft move.
Example Sentence 1
While taxiing to runway 27, the pilot stopped at the red and white sign marked '27-9' and held short until cleared to cross.
Example Sentence 2
A red and white sign marked the hold-short point before the runway.