What are CAT II and III holding position signs?
The stop sign for low visibility. A red sign naming the runway and its category, standing at a holding position set back from the runway to keep the ILS signal clear.
When visibility falls and aircraft land by instruments, the ILS signal must stay undisturbed. An aircraft waiting close to the runway can distort it. So a second holding position is set farther back, and a CAT II or III holding position sign marks it, so the pilot knows which limit applies in low-visibility operations.
1What it says
The inscription is the runway designator followed by the category: CAT I, CAT II, CAT III, or CAT II/III where one position serves both. It is white on red like every holding position sign, because it too means stop.
2Where it stands
A sign goes on each side of the taxiway, in line with the holding position marking and facing the approaching aircraft. The marking is the ladder-style Pattern B, which tells a pilot this is a set-back position, not the standard Pattern A hold beside the runway.
3Why it is set back
The further position keeps aircraft and vehicles outside the protected ILS area while low-visibility procedures are in force. Air traffic control then decides when an aircraft may move on to the standard holding position and on to the runway.
| Element | Rule |
|---|---|
| Colour | White inscription on a red background |
| Lighting | Retroreflective or illuminated as Annex 14 requires; for low-visibility operations they are normally lit |
| Class | Mandatory instruction sign: must be obeyed |
| Inscription | Runway designator followed by CAT I, CAT II, CAT III or CAT II/III, for example 27 CAT II/III |
| Position | On each side of the taxiway, in line with the holding position marking, facing the approaching aircraft |
| Marking | Pattern B (ladder-style) holding position marking at the set-back position; on a long marking the legend CAT II or CAT III is also painted along it |
| Meaning | Stop. Hold here in low-visibility operations until air traffic control clears you forward |
| Works with | Standard runway holding position sign, stop bars and ILS critical area signs |
Frequently Asked Questions
Q1What is a CAT II or III holding position sign?
A red sign with a white inscription made of the runway designator followed by CAT II, CAT III or CAT II/III. It marks a holding position farther from the runway than the standard one, used in low-visibility operations.
Q2How is it different from the ordinary runway holding position sign?
The ordinary sign names the runway, for example 27-09, at the standard holding position. The CAT II/III sign adds the category to the runway designator and stands at a second holding position set back from the runway.
Q3Why is there a second holding position?
In low visibility, aircraft and vehicles near the runway can disturb the ILS signal. The set-back position keeps them clear of the protected ILS area until air traffic control allows them forward.
Q4Where is the sign placed?
On each side of the taxiway, in line with the holding position marking, facing the aircraft approaching along the taxiway. The marking is the ladder-style Pattern B.
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