What is sign alignment?
A sign can sit at the right distance and height and still be hard to read. Alignment is how it is turned, held upright and lined up so the pilot sees its face squarely and in the right order.
Installation fixes where a sign stands. Alignment decides how it is seen. Signs are read by pilots moving along a taxiway or runway, often at an angle and in poor light, so a sign that is turned away, leaning, or out of step with its neighbours loses legibility even when its position is correct.
1Face the approach
Each sign is turned so its face is square to the direction of approach, toward the pilot who needs the message. A holding-position sign faces the aircraft approaching the holding position, and a guidance sign faces traffic on the route it serves. A face turned away is foreshortened, so the legend looks narrower and the luminance reaching the pilot falls.
2Upright, level, in line
The sign is held plumb and level on its mounting. A lean or twist shifts the face off the approach and makes the legend read crooked. Where several signs stand together, their faces are set in line and at one setback, so the group reads as one arrangement and no sign hides another.
3Read in the right order
A group is read left to right, so direction signs are placed in the order of the turns they show, with the location sign positioned so it reads correctly beside them. A sign swapped, rotated or fitted the wrong way round gives the pilot a wrong turn. Alignment is checked on site against the layout drawing and, after dark, with the signs lit.
| What is aligned | Checked against |
|---|---|
| Face direction | Square to the direction of approach along the taxiway or runway |
| Upright and level | Plumb sides and a level top, with no lean or twist in the structure |
| Line of a group | Faces in line and at one setback, so the group reads as a set |
| Legend order | Arrows and designators in the order of the turns, left to right |
| Clear view | No sign, post or equipment hiding another sign's face |
| Tolerance | Manufacturer's manual and the aerodrome or regulator's specification |
Frequently Asked Questions
Q1What does sign alignment mean?
Alignment is how the sign sits in space once it is installed: which way its face points, whether it is upright and level, and how it lines up with the signs next to it. A sign can be at the right setback and height and still be badly aligned.
Q2Which way should a sign face?
Toward the pilot who needs it, so the face is square to the direction of approach along the taxiway or runway. A holding-position sign, for example, faces the aircraft approaching the holding position. A face turned away from the approach is foreshortened and harder to read.
Q3Why does the left-to-right order of signs matter?
Pilots read a group of signs from left to right and match each arrow to a turn. Direction signs are therefore placed in the order of the turns they show, with a location sign placed so it reads correctly beside them. A sign swapped or turned the wrong way sends the pilot the wrong way.
Q4Who sets the alignment tolerance?
The manufacturer's installation manual and the aerodrome's own specification or national regulator. This page describes the principle and does not give a tolerance figure. Use the figure in the documents in force at your site.
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