Mandatory instruction signs

Mandatory instruction signs mark the places where an aircraft or vehicle must stop and hold until it is cleared to go on — most importantly at the entrance to a runway. They carry a white inscription on a red background.

[B 04-22] Combined sign at a runway holding position: yellow-on-black location sign B and red runway designation sign 04-22 in a gray steel sign box

What a mandatory instruction sign is

A mandatory instruction sign identifies a location beyond which an aircraft taxiing or a vehicle must not proceed unless it is authorised to do so by air traffic control. In practice that means the entrance to a runway, an ILS or MLS critical/sensitive area, or another restricted area on the movement area.

To make the instruction unmistakable, these signs use the strongest colour combination on the airfield: a white inscription on a red background. Where extra contrast is needed, the white characters may carry a black outline. This is the same convention under ICAO Annex 14 Volume I, EASA CS-ADR-DSN and the FAA's advisory circulars, so a red sign means "stop and hold" wherever you fly.

How they differ from information signs

Every other airfield guidance sign in this family is an information sign — yellow and black — and is there to help you find your way. A mandatory instruction sign is the opposite: it is an instruction, not a suggestion. At a runway-holding position or an ILS/approach holding position, crossing without clearance is a runway incursion; other mandatory signs — a no-entry or a road-holding position sign — protect areas away from the runway, but the rule is the same: do not pass without authorisation. That single distinction — red versus yellow — is the first thing to read on any airfield sign.

Types of mandatory instruction sign

The red signs you will meet on a taxiway are:

Runway-holding position sign — the "hold short" sign at the entrance to a runway, showing the runway designation.
CAT I/II/III holding position sign — the more distant runway-holding position that protects the ILS during low-visibility CAT I/II/III operations.
No entry sign — the white-bar-on-red symbol marking a one-way taxiway or an area you may not enter.
Runway approach area holding position sign — protects the approach and departure area of a runway (the FAA "15-APCH" sign).
ILS critical area holding position sign — protects the ILS critical and sensitive areas.

Draw them accurately in Wingframe

Wingframe lets you draw mandatory instruction signs to ICAO, EASA and FAA geometry — correct proportions, character heights, borders and colours — and share them with airports, consultants and manufacturers without the back-and-forth of manual drafting. See what Wingframe can do.