VDGS: Visual Docking Guidance System & Stand Lead-In Lights
A VDGS helps a pilot align an aircraft with its stand and stop at the designated position. This guide covers VDGS and A-VDGS operation, components, stand lead-in guidance, MARS stands, installation, commissioning, maintenance and procurement.
Guiding Aircraft Into the Stand
A Visual Docking Guidance System (VDGS) assists pilots in aligning an aircraft with its assigned parking stand and stopping at the designated position.
The system can display guidance such as lateral alignment, distance to the stopping position, closing rate and a stop indication. Advanced Visual Docking Guidance Systems (A-VDGS) may also identify the intended aircraft type, provide sensor-based guidance and display additional safety information.
VDGS is particularly important at stands where accurate aircraft positioning is required because of passenger boarding bridges, fuel hydrants, fixed ground-service installations or other stand infrastructure.
VDGS is related to airport apron infrastructure, but it is distinct from Airfield Ground Lighting (AGL) systems used for runway and taxiway visual guidance. Aircraft stand markings, stand lead-in guidance lights and VDGS may work together, but each has a different function.
This guide explains the VDGS operating concept, system components, stand lead-in guidance, installation, testing, maintenance and integration considerations.
What Is a VDGS Airport System?
A Visual Docking Guidance System is an airport visual aid that helps a pilot guide an aircraft into its assigned stand and reach the required stopping position.
The system provides visual information during the docking manoeuvre. Depending on its design, it may use passive visual indicators or active sensors and an electronic display.
A VDGS generally provides two primary functions:
Azimuth guidance
Helps the pilot maintain the intended stand centreline.
Stopping guidance
Indicates the intended stopping position and helps the pilot bring the aircraft to a controlled stop.
An advanced system can provide additional information, including aircraft type, lateral displacement, distance to go, closing rate and emergency-stop indications. These functions are described in the EASA Easy Access Rules for Aerodromes, revised March 2026, particularly the provisions concerning visual and advanced visual docking guidance systems.
Why Is VDGS Required at Some Aircraft Stands?
Accurate stopping can be important where the aircraft must be positioned correctly relative to:
- Passenger boarding bridges.
- Fixed aircraft servicing installations.
- Fuel hydrants.
- Stand equipment and infrastructure.
- Designated aircraft parking positions.
- Multiple aircraft positions within a shared stand arrangement.
The need for VDGS depends on stand geometry, aircraft types, operating conditions, positioning accuracy and the availability of suitable alternative guidance methods.
VDGS is not a substitute for the airport's approved aircraft parking and apron operating procedures.
VDGS and A-VDGS: What Is the Difference?
The terms VDGS and A-VDGS are related, but they do not always describe identical functionality.
A basic VDGS may provide azimuth and stopping guidance using indicators designed for the intended aircraft stand and operating conditions.
An Advanced Visual Docking Guidance System adds active guidance functions, commonly based on sensors and electronic processing.
VDGS Comparison
| Feature | Basic VDGS | Advanced VDGS |
|---|---|---|
| Stand alignment guidance | Provided through the specified visual guidance arrangement | May use active sensing and electronic alignment information |
| Stopping-position indication | Provided by the specified indicator or guidance unit | Typically integrated with active stopping guidance |
| Aircraft type identification | Depends on system design | May identify or display the selected aircraft type |
| Distance-to-stop information | Depends on the system | Commonly displayed |
| Closing-rate information | Depends on the system | May provide continuous closing-rate guidance |
| Lateral displacement information | May use a passive alignment display | May provide sensor-based lateral displacement |
| Malfunction indication | Required features depend on the applicable system specification | Includes provisions for indicating that the system is unavailable or unserviceable |
| Configuration | Depends on the required stand and operating arrangement | May require aircraft-type selection and configuration data |
| Integration | Depends on project requirements | May include additional monitoring and interface functions |
What Does an Advanced VDGS Display?
Depending on the equipment, an A-VDGS display may show the following information:
- Aircraft type or model selected for docking.
- Guidance indicating whether the aircraft is aligned with the stand centreline.
- Direction of correction where lateral displacement is detected.
- Distance remaining to the stopping position.
- Closing rate or approach-speed information.
- A warning when the intended stop position is reached or passed.
- An emergency STOP indication.
How Does a Visual Docking Guidance System Work?
A VDGS supports the aircraft's movement into the stand by presenting visual guidance to the pilot.
For an advanced system, sensors may determine the aircraft's position and movement relative to the stand. The system processes that information and updates the display according to its design.
The docking process can be understood in several stages.
Aircraft Acquisition
Where an active sensing system is installed, the system detects or acquires the approaching aircraft within its specified operating conditions.
The system must identify the aircraft or establish the relevant guidance information according to its approved design.
The assigned aircraft type and stand configuration must be correct before docking guidance is used.
Aircraft Type Verification
Some A-VDGS installations require selection or confirmation of the intended aircraft type or model.
This is important where different aircraft types use the same stand but have different stopping positions or clearance requirements.
An incorrect aircraft selection can result in misleading stopping guidance. The verification process must follow the airport's approved docking procedure.
Azimuth Alignment
The system provides information that helps the pilot maintain the designated stand centreline.
Depending on the design, this may use a visual alignment display, lateral displacement information or directional correction indications.
The display must be positioned and configured so that the intended user can interpret it clearly throughout the relevant manoeuvre.
Distance and Closing-Rate Guidance
An advanced system may display the distance remaining to the stop position and the aircraft's closing rate.
This information helps the pilot regulate the aircraft's movement as it approaches the designated stop point.
The usable operating conditions, display behaviour and performance limits must be defined for the selected equipment.
Stop Indication
At the designated stopping position, the system provides the specified STOP indication or equivalent stopping signal.
Some systems use colour changes to communicate whether the aircraft may continue or must stop. Under the EASA visual docking guidance provisions, green can indicate that the aircraft may proceed and red that the stop point has been reached, with a possible intermediate warning colour shortly before stopping where the system uses colour-change guidance.
The actual display convention must be understood from the applicable system documentation and airport procedure.
Emergency Stop or System Failure
Where the system provides an emergency STOP function, that indication must be treated according to the approved operating procedure.
Advanced systems also require a means to indicate when the system is unavailable or unserviceable. If valid guidance is not available, personnel must follow the airport's prescribed method for suspending or completing the docking activity.
Main Components of an Airport VDGS
The component arrangement varies by manufacturer and system type. A typical installation may include the following elements.
| Component | Function |
|---|---|
| Visual display unit | Presents docking and stopping guidance to the pilot |
| Position-sensing equipment | Detects relevant aircraft position or movement where active sensing is used |
| Sensor assembly | May use laser scanning, camera-based sensing or other specified technology |
| Processing and control unit | Processes system inputs and produces the required guidance outputs |
| Aircraft-type or stand-selection interface | Supports the approved configuration for the stand and intended aircraft |
| Stand configuration data | Defines relevant stand geometry, aircraft types and stopping-position information |
| Power supply | Provides the required electrical supply to the system |
| Communication interfaces | Support specified connections to operator interfaces or airport systems |
| Monitoring and fault reporting | Provides relevant status, fault and maintenance information where supported |
| Mounting arrangement | Positions the display and sensors for the required visibility and coverage |
| Emergency stop or safety interface | Supports the defined stop function where included in the approved system |
Aircraft Stand Lead-In Guidance
Aircraft stand lead-in guidance helps the pilot follow the intended route into the parking stand.
It may include painted stand centreline markings, stand identification signs, aircraft stand manoeuvring guidance lights and VDGS indications.
These elements complement each other but perform different functions.
5.1 Stand Lead-In Markings
Stand lead-in markings identify the intended path toward the aircraft parking position.
Their layout must account for the stand geometry, aircraft types, turning requirements and the intended stopping positions.
Continuous or broken lead-in markings may be used for different stand arrangements. For example, the Delhi aerodrome information published by AAI describes different stand lead-in markings for selected Multiple Aircraft Ramp System (MARS) arrangements.
The markings must be interpreted together with the approved stand layout and the applicable aerodrome procedures.
5.2 Aircraft Stand Manoeuvring Guidance Lights
Aircraft stand manoeuvring guidance lights are separate visual aids that can help guide aircraft along the lead-in, turning and lead-out portions of a stand route, where provided.
The EASA aerodrome specifications distinguish these lights from VDGS. In the referenced provisions, manoeuvring guidance lights other than those indicating a stop position are fixed yellow lights; lights used to indicate a stop position are fixed red lights. The detailed installation requirements depend on the applicable specification.
5.3 VDGS Versus Stand Lead-In Lights
| Feature | VDGS | Stand lead-in guidance lights |
|---|---|---|
| Primary purpose | Provides alignment and stopping guidance | Helps visually define the aircraft's path into or through the stand |
| Main information | May provide alignment, distance, closing rate and stop indications | Provides a visible route or manoeuvring reference |
| Aircraft-type information | May be supported by advanced systems | Not normally the primary function of the lights |
| Stop indication | Provided by the specified docking display or indicator | Dedicated stop-position lights may be provided where specified |
| Technology | Display, sensor and control equipment depending on system | Installed visual lighting elements |
| Design references | VDGS and A-VDGS requirements | Aircraft stand manoeuvring guidance-light requirements and approved layout |
VDGS Installation and Location Considerations
The location of the VDGS display and sensing equipment is important because the pilot must be able to interpret its indications during the docking manoeuvre.
Placement should be developed using the stand geometry, intended aircraft types, viewing angles and operational requirements.
6.1 Display Location
Consider the following factors when locating the guidance unit:
- Extension of the designated stand centreline.
- Visibility from the intended cockpit viewing position.
- Guidance continuity from the lead-in markings and any manoeuvring guidance lights.
- Clear interpretation of left/right alignment indications.
- Visibility of both alignment and stopping information.
- Required viewing conditions for the aircraft types using the stand.
- Mounting on a terminal building, pier, column or other approved support.
- Physical protection and access for maintenance.
6.2 Aircraft Types and Stand Geometry
The design should identify all aircraft types and models intended to use the stand.
Consider:
- Aircraft dimensions and cockpit position.
- Nose-wheel stopping position.
- Stand centreline and approach path.
- Passenger boarding bridge movement and range.
- Fuel-hydrant and service-equipment locations.
- Required aircraft clearances.
- The use of multiple stopping positions.
- Access for aircraft servicing vehicles.
- Stand sharing and aircraft changeover arrangements.
For a stand serving multiple aircraft types, ensure the configured guidance and stopping positions correspond to the aircraft assigned to the stand.
6.3 Glare, Sunlight and Background Lighting
The system must remain sufficiently clear under its specified operating conditions.
Reflections from sunlight, nearby floodlights, illuminated signs, building surfaces or other light sources can reduce display conspicuity.
The installation design should therefore assess the display's visibility during day and night, its viewing angles, background brightness and potential glare or reflection.
This consideration is specifically addressed in the EASA aerodrome guidance for VDGS.
6.4 Weather and Environmental Conditions
The equipment must be suitable for the weather, visibility and ambient-light conditions in which it is intended to be used.
Review the manufacturer's specified operating limits and the airport's environmental conditions, including relevant temperature, moisture, wind, dust and contamination exposure.
The system must only be used within the operating conditions for which its performance is specified.
6.5 Installation Coordination
Coordinate the VDGS with other stand systems, including:
- Aircraft stand markings and identification signs.
- Stand lead-in guidance lights.
- Apron floodlighting.
- Passenger boarding bridges.
- Stand power and communication infrastructure.
- Fuel hydrants and fixed servicing equipment.
- Service roads and vehicle routes.
- Drainage, underground utilities and civil works.
- Maintenance access and replacement requirements.
Multiple Aircraft Ramp System (MARS) and Multi-Position Stands
A Multiple Aircraft Ramp System (MARS) stand may accommodate different aircraft configurations using shared apron space and more than one designated stand centreline or stopping position.
This arrangement introduces additional coordination requirements for docking guidance.
Important MARS Considerations
- Correct identification of the stand and intended aircraft position.
- Accurate selection of the relevant centreline and stopping position.
- Compatibility with the aircraft types assigned to each configuration.
- Clear indication of which VDGS is active.
- Prevention of conflicting guidance between different stand positions.
- Coordination of shared displays or sensing equipment, where used.
- Interlocking or other controls required by the approved system design.
- Clear markings and stand identification.
- Appropriate emergency stop arrangements.
- Defined responsibility for changing stand configuration.
Where several VDGS units or centreline options are installed, the control arrangement must prevent conflicting active guidance in accordance with the approved design.
VDGS Electrical Supply, Controls and Interfaces
VDGS power and control design depends on the selected system and installation.
The electrical and interface design should identify the supply requirements, protective devices, cable routes, communication interfaces and equipment isolation arrangements.
8.1 Electrical Design Considerations
- Confirm the manufacturer's supply and operating requirements. A VDGS is normally an electronic unit fed from the stand’s low-voltage distribution rather than from a series AGL circuit; stand manoeuvring guidance lights may be on either arrangement, so confirm each from the approved design.
- Provide the specified distribution and electrical protection.
- Verify earthing and bonding requirements where applicable.
- Select suitable cables and connections for the site conditions.
- Coordinate routing with apron infrastructure and underground services.
- Provide an appropriate isolation arrangement for maintenance.
- Protect connections from the specified environmental exposure.
- Provide the required circuit and asset identification.
- Establish the required monitoring and fault reporting.
- Ensure that the installation is documented in the approved drawings.
8.2 Control and Monitoring Interfaces
Depending on the project, a VDGS may provide information to, or exchange information with, specified airport control, monitoring or stand-management systems.
Possible interfaces depend on the equipment and project scope. They should not be assumed to be present in every installation.
The design should document:
- Interface purpose and ownership.
- Signal or communication requirements.
- Relevant status and fault indications.
- Configuration responsibility.
- Emergency stop and system-unavailable behaviour, where applicable.
- Integration test requirements.
- Maintenance and troubleshooting responsibilities.
8.3 VDGS Is Not the Same as AGL or ALCMS
VDGS, AGL and an Airfield Lighting Control and Monitoring System (ALCMS) have different primary functions.
| System | Primary function |
|---|---|
| VDGS | Assists aircraft alignment and stopping at the parking stand |
| AGL | Provides visual guidance for runway, taxiway and other airfield movement-area operations |
| ALCMS | Controls and monitors the relevant airport lighting systems according to its approved scope |
| Apron floodlighting | Illuminates aircraft stands and associated working areas |
VDGS Testing and Commissioning
Commissioning verifies that the installed system functions according to its approved configuration, the manufacturer's requirements and the project acceptance criteria.
Testing must be performed by appropriately authorized personnel using the specified procedure.
9.1 Pre-Commissioning Review
Pre-commissioning
9.2 Functional Verification Checklist
| Test area | What to verify |
|---|---|
| Display visibility | Guidance is clear from the intended viewing positions under specified conditions |
| Aircraft-type configuration | Correct type or model is selected or detected as required by the system |
| Azimuth guidance | The display provides the specified alignment information |
| Distance indication | The stopping-distance information behaves as specified |
| Closing-rate indication | Where provided, the indication meets the system requirements |
| Stop indication | The system provides the specified stopping signal |
| Emergency stop | The required emergency-stop indication and associated function are verified |
| Unserviceable indication | The required method of indicating an unavailable or faulty system operates correctly |
| Sensor performance | Applicable detection and tracking functions meet the specified requirements |
| Stop-position accuracy | The configured stop point is verified using the approved method |
| Stand configuration | Correct operation is confirmed for each approved stand and aircraft configuration |
| Interface functions | Required control, status and monitoring interfaces operate as specified |
| Environmental operation | Performance is assessed under the conditions and procedure defined for the project |
| Records | Results, deviations and required approvals are documented |
9.3 Calibration and Stop-Position Verification
Where the system uses aircraft-type data, sensors or configured stopping positions, calibration and alignment must follow the specified procedure.
The acceptance process should verify that the configured guidance corresponds to the assigned stand and intended aircraft configuration.
9.4 Acceptance and Handover
The handover documentation may include:
- Approved drawings and equipment layout.
- Installed equipment list and asset identifiers.
- Manufacturer datasheets and manuals.
- Configuration and setup records.
- Test and commissioning reports.
- Calibration or alignment records, where applicable.
- Approved interface documentation.
- Outstanding defect and punch-list records.
- Training and maintenance information.
- Warranty and service-support details.
- Required acceptance and handover approvals.
A system should be accepted and placed into operational use only through the approved airport process.
VDGS Maintenance and Troubleshooting
Regular maintenance helps preserve the performance and reliability of the guidance system.
The maintenance programme should follow the manufacturer's instructions, airport requirements, observed reliability and the system's specified operating conditions.
10.1 Routine Maintenance Checklist
Routine maintenance
10.2 Common VDGS Fault Symptoms
| Symptom | Possible areas to investigate |
|---|---|
| Display blank or inactive | Power supply, protection, equipment status or display hardware |
| Aircraft not acquired | Sensor condition, configuration, environmental conditions or system fault |
| Wrong aircraft type displayed | Configuration, selection process or aircraft-identification function |
| Alignment indication abnormal | Sensor alignment, stand reference data or equipment issue |
| Distance indication unstable | Sensing, configuration, communication or system fault |
| Stop indication unavailable | Display, control logic, configuration or equipment fault |
| Unserviceable indication active | Recorded system fault and manufacturer diagnostic information |
| Communication failure | Network, interface, power or configuration issue |
| Intermittent fault | Power, connection, environmental or electronic component concern |
What Happens if VDGS Is Unserviceable?
An unserviceable VDGS may affect the airport's ability to guide aircraft into the stand using that system.
The response depends on the airport's approved apron operating procedure, the stand configuration and the availability of authorized alternative guidance.
Alternative methods may include a trained aircraft marshaller or another approved stand-guidance arrangement, where permitted by the applicable procedures.
General Response to a VDGS Failure
Record and report the fault through the airport's prescribed channel.
Identify the affected stand and equipment.
Establish the system status and relevant fault information.
Inform the responsible airport operational personnel.
Follow the approved procedure for stopping, suspending or continuing the docking operation under an authorized alternative method.
Arrange authorized maintenance and fault investigation.
Perform the required testing after corrective work.
Document the serviceability status and required operational handback.
VDGS Procurement and Technical Evaluation Checklist
Selecting a VDGS involves more than comparing the purchase price of the display unit.
The system must suit the aircraft stand, aircraft types, operational conditions, installation constraints and required functionality.
Technical Evaluation
Technical evaluation
Commercial Evaluation
Compare supplier quotations on an equivalent scope, including:
- Display and sensing equipment.
- Controllers, software and licenses where applicable.
- Stand configuration and aircraft data setup.
- Mounting structures and installation accessories.
- Power, communications and associated infrastructure.
- Civil or electrical installation works where included.
- Integration with existing systems.
- Factory or site testing where specified.
- Commissioning, calibration and acceptance.
- Training, manuals and maintenance documentation.
- Warranty, spare parts and after-sales support.
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VDGS FAQ
Q1What does VDGS stand for?
VDGS stands for Visual Docking Guidance System. It provides visual guidance to assist aircraft alignment and stopping at a designated parking stand.
Q2What is the difference between VDGS and A-VDGS?
A-VDGS means Advanced Visual Docking Guidance System. An advanced system may use sensors and electronic processing to provide aircraft-type information, lateral displacement, distance-to-stop, closing-rate and emergency-stop indications.
Q3Is VDGS an airfield lighting system?
VDGS is an airport visual guidance system associated with aircraft docking. It is related to apron infrastructure but is distinct from runway and taxiway lighting systems. Its primary purpose is to guide the aircraft into the assigned stand and to the designated stopping position.
Q4What are airport stand lead-in lights?
Stand lead-in guidance lights help define the intended aircraft path or manoeuvring route where provided by the design. They are distinct from VDGS displays, which provide alignment and stopping guidance. Their exact arrangement and requirements must be checked against the approved stand layout and applicable standards.
Q5How does VDGS know where the aircraft should stop?
Depending on the system, the required stopping information may be based on configured stand and aircraft data, position sensing or a combination of these functions. The selected configuration must match the intended aircraft and stand arrangement.
Q6Does every VDGS identify the aircraft type automatically?
No. Aircraft identification and selection capabilities vary by system. Some installations may require aircraft-type selection or confirmation, while advanced systems may provide automated or sensor-based identification features.
Q7What does a red STOP indication mean?
The meaning and required response are defined by the system's display conventions and the airport's operating procedure. Where the system displays an emergency or required-stop indication, follow the applicable docking procedure and stop guidance.
Q8What happens when VDGS fails?
The fault must be reported and managed under the airport's approved procedure. A trained marshaller or other authorized alternative guidance method may be used where permitted. Do not assume the aircraft can continue using the same docking method with an unserviceable system.
Q9Is VDGS connected to ALCMS?
Not necessarily. VDGS and ALCMS have different primary functions. Any connection between VDGS and airport control, monitoring or other systems depends on the approved project architecture and specified interfaces.
Q10How often should VDGS be maintained?
The inspection and maintenance schedule depends on the equipment manufacturer's requirements, airport maintenance programme, environment and observed reliability. Use the approved schedule for the installed system.
Q11What is a docking guidance system at an airport?
A docking guidance system at an airport helps a pilot park an aircraft accurately at a stand. It shows the aircraft type, centreline guidance, distance to stop and a stop indication on a display unit ahead of the aircraft. A visual system uses displays and signals read by the pilot, while an advanced system also detects and identifies the aircraft.
Q12What is an aircraft docking guidance system, and how does a docking guidance system airport installation relate to stand lead-in lights?
An aircraft docking guidance system gives the final alignment and stopping information on the stand. Airport stand lead-in lights are a separate arrangement of lights on the apron that lead the aircraft from the taxilane to the stand before the docking unit takes over. The two are often used together, and the project design defines how.
Clear, Coherent Stand Guidance
VDGS is an important part of aircraft stand guidance where accurate alignment and stopping are required. Reliable operation depends on correct stand configuration, clear display indications, suitable installation, verified performance and an effective maintenance process.
Stand markings, manoeuvring guidance lights and VDGS should work together without conflicting indications. The system must be used only within its specified operating conditions and in accordance with the airport's approved procedures.
This page provides general educational guidance. Final VDGS selection, design, installation, commissioning, maintenance and operational use must follow the applicable aerodrome standards, approved airport documents and manufacturer instructions.
Technical References
- ICAO Annex 14, Volume I — Aerodrome Design and Operations — international aerodrome design requirements, including aircraft stand visual docking guidance provisions.
- EASA Easy Access Rules for Aerodromes — March 2026 revision — detailed provisions for visual docking guidance, advanced VDGS and aircraft stand manoeuvring guidance lights.
- AAI Aeronautical Information Publication — Delhi aerodrome information — example of airport-specific stand markings and A-VDGS availability.
- ICAO Regional Guidance — Initiatives to Promote Safe and Efficient Apron Management — background on stand entry guidance, stopping positions and aircraft stand operations.
Engineering & Expert Notes
Configuration Must Match the Aircraft Types
SetupVerify stop positions and aircraft profiles against the stand's intended use.
Confirm Alignment With the Stand Centreline
AlignmentCheck against surveyed markings and recheck after resurfacing.
Test in Different Lighting Conditions
VisibilityVerify display visibility in daylight, night and adverse weather.
Check Interfaces With Building Systems
IntegrationTest links to power, control and any airport systems.
Define What Happens When It Is Unserviceable
FallbackAgree marshalling and procedures in advance.
Record Commissioning Data
RecordsKeep settings and acceptance data for maintenance.
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