AGNIS VDGS
Azimuth Guidance for Nose-In Stand is one of the most popular forms of stand guidance. It consists of two coloured lights mounted side by side.
If the pilot is on the stand centreline they will see two green lights. If they are off centreline, one of the lights will appear red and the pilot then steers towards the green one. AGNIS alone provides only azimuth guidance, it does not inform pilots when they should stop. It is relatively imprecise but cheap to implement and reliable.
Read more about this topic: Visual Docking Guidance System