ICAO Annex 14, Volume I is the global baseline for airfield guidance signs. Chapter 5.4, “Signs”, defines the sign families, their colours and inscriptions — the standard EASA, the FAA and national authorities harmonise against.
The International Civil Aviation Organization (ICAO) is the United Nations agency that sets the worldwide standards for civil aviation. Its aerodrome standards live in Annex 14 to the Chicago Convention, Aerodrome Design and Operations. This page draws on Annex 14, Volume I, 9th edition (2022), incorporating Amendment 15.
Annex 14 is the document every other authority on this site harmonises against: EASA's CS-ADR-DSN transposes it for Europe, and while the FAA writes independent standards, it recognises the same two sign families. When people talk about a sign being "ICAO", they mean it follows Annex 14.
Signs are covered in Chapter 5, Visual aids for navigation, at section 5.4, Signs. The general rules in §5.4.1 set out that signs are frangible, rectangular with the longer side horizontal, and — crucially — that red is reserved for mandatory instruction signs (§5.4.1.5), so a red sign always means an instruction. Two families follow:
Beyond the two families, §5.4 also defines the VOR aerodrome check-point sign (§5.4.4), the aerodrome identification sign and aircraft stand identification signs.
The geometry of a sign — character height, stroke width, face size — is set out in Appendix 4 and keyed to the runway code number. The legend (character) height is one of three values — 200 mm, 300 mm or 400 mm — with the taller legends used on the higher runway codes, and the arrow and character stroke width follows at 32 mm, 48 mm and 64 mm respectively.
Amendment 15 reduced the minimum sign-face heights to 1.5 times the legend height: a 200 mm legend now needs a face at least 300 mm high, a 300 mm legend 450 mm, and a 400 mm legend 600 mm (down from the earlier 2× values). Where a mandatory instruction sign is provided on one side of the taxiway only, its face has a minimum width of 1.46 m at runway code 1–2 and 1.94 m at code 3–4. This is one of the details where ICAO and EASA now differ — EASA still specifies the older 2× face heights.
Annex 14 sets the sign's colours, inscription and proportions. Exactly where a sign is sited, how it is illuminated and its retroreflectivity are covered by other provisions and guidance material (the Aerodrome Design Manual, Doc 9157). This reference concentrates on the sign face itself — the part a designer draws.
Wingframe draws airfield guidance signs to the ICAO Annex 14 geometry — the reserved-red rule, the Appendix 4 legend heights and stroke widths, and the family colours — so the sign you design matches the standard it will be built and inspected against. See what Wingframe does.