How does a VDGS detect the aircraft with a laser or sensor?
There is no marshaller and no mirror. A sensor finds the aircraft, follows it, and turns what it measures into the offset and the distance the display shows.
A modern docking system measures the aircraft instead of relying on the pilot's eye. A sensor mounted with the display finds the aircraft as it enters the stand, follows it, and works out the two numbers the display needs: the offset from the stand centreline and the distance to the stop point.
1Scan, detect, track
A laser scanner sends pulses across an angle and measures the range of each one. Range against angle gives a profile of whatever is in front of it. When a surface of aircraft size and shape enters the capture zone, the system acquires it and keeps scanning to follow it. Some systems use cameras or radar instead of, or alongside, lasers.
2From echoes to guidance
The system finds the nose in the profile and converts its position into the offset for the azimuth display and the distance for the stopping display. The same profile can be compared with the selected aircraft type, which is covered separately. Annex 14 sets what the guidance must achieve, such as accuracy and use in the weather and light it is intended for, but not which sensor does the job.
3Eye-safe and weather-aware
The laser is designed to be eye-safe for people on the apron, and its class and any limits come from the manufacturer. Rain, fog, snow, a dirty window or direct sun can shorten the range or add noise, so each system states the conditions it is designed for.
4What goes wrong
A dirty or fogged window blinds the scanner. A sensor knocked out of calibration guides the pilot to the wrong line. A vehicle or person in the scan field can be mistaken for the aircraft, or hide it. If the sensor loses the aircraft, the display should show a clear fault indication, not a frozen last position, and the stand's procedures take over.
| Stage | What the sensor does | Result |
|---|---|---|
| Capture | Detects an aircraft-sized object entering the capture zone | Aircraft acquired |
| Track | Repeats scans of range and angle | Position and closing speed |
| Compute | Finds the nose in the profile | Offset and distance to go |
| Verify | Compares the profile with the selected aircraft type | Type confirmed, or an alert |
| Display | Drives the azimuth and stopping displays | Steer, slow, stop |
| Fault | Window blocked, aircraft lost, profile mismatch | Clear fault state; procedures take over |
Frequently Asked Questions
Q1How does laser detection of an aircraft work?
A laser scanner sends out pulses across an angle and measures how far away each one is. Range against angle gives a profile of whatever is in front of it. When a surface that matches an aircraft enters the capture zone, the system acquires it and keeps scanning to follow it. The nose position in the profile gives the offset and the distance to go.
Q2Do all docking guidance systems use lasers?
No. Laser scanners are common, and some systems use cameras or radar instead of or alongside them. ICAO Annex 14 sets what the docking guidance must achieve, such as accuracy and use in the weather and light conditions it is intended for, but it does not say which sensor does the job.
Q3Is the laser safe for people on the apron?
Systems are designed so the laser is eye-safe for people on the apron, but the laser class and any limits on use are set by the manufacturer and the local rules. Take them from the manufacturer's data and the airport operator's safety procedures.
Q4What can reduce the sensor's performance?
A dirty or fogged window, heavy rain, snow or fog, and direct sun on the sensor can all shorten its range or add noise. Manufacturers state the conditions the system is designed for, so check the limits against your climate and stand layout.
Q5Why must the system tell an aircraft from a vehicle?
Ground vehicles, equipment and people may be inside the scan field before and during docking. If one is mistaken for the aircraft, or hides it, the display will show wrong guidance. The system uses the size and shape of the profile to accept only aircraft-like objects.
Q6What happens if the sensor loses the aircraft?
The display should go to a clear fault or no-guidance indication rather than keep showing the last position, and the stand's procedures take over, for example a marshaller. The exact behaviour depends on the system, so check it against the manufacturer's data and the operator's procedures.
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