Visual Docking Guidance System

A stand guidance system is a system which gives information to a pilot attempting to park an aircraft at an airport stand, usually via visual methods, leading to the term Visual Docking Guidance System (VDGS) and also A-VDGS (the A standing for advanced) This allows them to remain clear of obstructions and ensures that jetways can reach the aircraft.

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.

The Parallax Aircraft Parking Aid is frequently combined with an AGNIS system, informing flight crews when to stop. The device features no electronics or moving parts; it consists simply of a large grey box (usually with one or more sides missing) with a large rectangular slot cut into the front.

Inside the box, towards the rear, is a white stick or fluorescent tube, which appears to move from one side of the slot to the other as the viewer moves closer, although it is in fact fixed and the effect is merely due to perspective (see parallax). Above and/or below this slot will be markings in white or yellow, indicating where different types of plane should stop.

As this system relies on the position of the viewer, it will not give accurate distance information to aircraft which have deviated significantly from the stand centreline.

This is a simple two phase traffic light with red and green lights, mounted to the side of the AGNIS lights. Typically these are round and mounted vertically, in order to avoid confusion to AGNIS lights which are also red and green but mounted side by side and usually square.

Used in combination with AGNIS at stands which can only accept smaller airliners, it features one or two mirrors, allowing the flightcrew to see ground markings in relation to their nose wheel, when it is within the area they need to stop. Typically two mirrors are used, angled differently to suit the various heights of cockpits from the ground.

Advanced Visual Docking Guidance Systems feature electronic displays which perform the functions of an AGNIS/PAPA installation, although with much greater accuracy. They may also provide collision avoidance from static objects.

A-VDGS systems will usually have emergency stop buttons located both on the stand and in the jetway/gate area, which causes the stop indication to appear immediately.

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