Different signs
Mandatory, location, direction and destination: four airfield signs told apart by colour, arrow and placement, each answering a different question for the pilot.
The colour coding is the whole logic of the airfield sign system. Red is reserved for mandatory signs and yellow and black mark the information signs. A mandatory sign marks a limit not to be crossed without clearance, as at a runway holding position (a NO ENTRY sign is also mandatory: do not enter). The location, direction and destination signs are information signs: they guide, and carry no prohibition of their own.
The three guidance signs are told apart by colour and arrow. A location sign is yellow on black and never carries an arrow, because it only confirms where the aircraft is. A direction sign is the inverse, black on yellow, and always carries an arrow. A destination sign looks like a direction sign but names an area rather than a taxiway. Location and direction signs are often placed together as a combined sign.
Marks a limit that must not be passed without clearance, as at a runway holding position. An aircraft or vehicle holds there until ATC gives an explicit clearance.
Location, direction and destination signs guide the pilot. They say where you are and where to go, and do not forbid anything.
| Aspect | Mandatory sign | Location sign | Direction sign | Destination sign |
|---|---|---|---|---|
| Colours | White inscription on red | Yellow inscription on black, with a yellow border when it stands alone | Black inscription on yellow | Black inscription on yellow |
| Answers | What must I not cross without clearance? | Which taxiway or runway am I on? | Which taxiway do I take next? | Which way to a general area? |
| Inscription | The runway designators or the restricted area | A taxiway or runway designator | A taxiway designator | A functional area, such as a cargo apron, terminal or de-icing pad |
| Arrow | None; it marks a limit | Never | Always, drawn to match the turn | Always, pointing toward the area |
| Where | At the holding position or the edge of the area it protects | Beside the taxiway it names, alone or together with a direction sign | Before the intersection it serves, normally on the left of the taxiway | Where the pilot needs to choose a route, as the design requires |
| Pilot must | Hold until ATC gives an explicit clearance | Note position; no action is required | Choose the turn shown | Follow the arrow toward the area; direction signs then guide the route |
| If it is dark or faded | A pilot may miss a stop instruction at a holding position | Position is harder to confirm | The next turn is harder to read | Route to the area is harder to read |
What to check on signs
Right sign, right message
Check the inscription, arrow and designators against the airfield design and the taxiway chart.
Colour and legibility
Check the face colours are correct and not faded, and the legend is clean and readable by day and at night.
Even illumination
Check the whole face lights evenly. Dark patches, flicker or a dark sign are faults to log and fix.
Position and alignment
Check the sign stands where the design puts it and faces the pilot it is meant for.
Frangible mounting
Check the mounting is intact and frangible as designed, with no damage from impacts or vehicles.
Isolate before work
Isolate and lock out the circuit before working on a sign, its transformer or its connectors.
Frequently Asked Questions
Q1What are the main types of airfield sign?
Four common ones are the mandatory sign, the location sign, the direction sign and the destination sign. The mandatory sign is the stop sign of the airfield. The other three are information signs: the location sign says where the aircraft is, the direction sign says which taxiway comes next, and the destination sign points toward a functional area.
Q2How do the colours tell the signs apart?
A mandatory sign is white on red. A location sign is yellow on black, with a yellow border when it stands alone. A direction sign and a destination sign are black on yellow. Red is reserved for mandatory signs.
Q3Which signs carry an arrow?
Direction signs and destination signs always carry an arrow. Location signs never do, because they only confirm position. Mandatory signs name the runway or area and are not guidance signs.
Q4What is the difference between a direction sign and a destination sign?
They look the same: yellow background, black inscription and an arrow. The difference is the inscription. A direction sign names a taxiway designator, while a destination sign names a general area such as a cargo apron, terminal or de-icing pad.
Q5What limits and requirements apply?
Colours, sizes, luminance and placement come from the standard, such as ICAO Annex 14 or the FAA specifications, and from the airport's design. Use the requirements for your site, and isolate and lock out the circuit before working on a sign, its transformer or its connectors.
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