Mandatory Instruction Signs

More information about mandatory instruction signs can be found in the AIM:

Mandatory instruction signs always have a red background with a white inscription. They are used to denote:

Entrance to a runway or critical area
Areas where an aircraft is prohibited from entering

Runway Holding Position Sign

This sign will be located at holding positions on taxiways that intersect a runway or on runways that intersect other runways.

The inscription on the sign contains the designation of the intersecting runway, as shown below:

In the image above, the runway 15 threshold would be to the left and the runway 33 threshold would be to the right.

When the taxiway is located at the end of the runway, only the designation of the takeoff runway may appear on the sign, as shown below:

Taxiways That Intersect the Intersection of Two Runways

When this happens, signs will indicate the intersecting runways and include arrows pointing in the relative direction to each runway threshold, as shown below:

Runway Approach Area Holding Position Sign

These are used to hold aircraft on a taxiway located in the approach or departure area for a runway so that the aircraft does not interfere with operations on that runway. An example of this sign is below:

ILS Critical Area Holding Position Sign

This sign is used to hold aircraft outside of the ILS critical area. An example of this sign is below:

No Entry Sign

A no entry sign simply denotes that aircraft should not enter a specific area.

These can be used in locations where aircraft are only intended to move in one direction.