7th November 2020 /// asmgcs, smgcs, levels review….

A-SMGCS Levels of Implementation.

An A-SMGCS is a system that supports surface movement operations at an aerodrome based on defined operational procedures. A-SMGCS provides surveillance, routing, planning and guidance for the control of vehicles and aircraft to maintain a declared surface movement rate. This must be achieved under all weather conditions while maintaining the required level of safety.

A-SMGCS

A-SMGCS is a modular architecture consisting of different airfield-based systems providing data which is fused into an information system which supports the safe, orderly, and timely movement of aircraft and vehicles on aerodromes under all operational requirements, considering the density of the aerodrome traffic and the complexity of the taxiway layout. The system provides this functionality independent of the line -of-sight visibility between the controller and the aircraft/vehicle.

The main modules of an A-SMGCS system comprise of a surveillance system which provides the position, identification and tracking of aircraft/vehicles around the aerodrome, a routing system which generates the paths on the ground followed by the aircraft/vehicles, a guidance system that provides the functions such as automated switching of Taxiway Centreline Lights (TCL) and Stop Bars and the automated activation of Advanced Visual Docking Guidance systems (A-VDGS), and finally the Airport Safety Support System that provides the functions such as runway monitoring and conflict alerting (RMCA), conflicting ATC clearances (CATC) and conformance monitoring alerts for controllers (CMAC).

However, A-SMGCS is more than just a set of systems, it also includes complementary procedures and at the lower levels of implementation aims to deliver improved situational awareness to controllers. Higher levels of implementation deliver safety nets, conflict detection and resolution as well as planning and guidance information for pilots, drivers, and controllers. Information from the A-SMGCS can be used to provide inputs for the A-CDM

The surveillance system is the minimum service that must be implemented and is a key enabler for the all the other functions. The routing service is required to allow the guidance service to function and depending upon the local aerodrome requirements, the guidance service and some aspects of the Airport Safety Support System may be partially introduced although not all CATC and CMAC alerts may be appropriate depending on the aerodrome layout. Indeed, the guidance service would be difficult to implement if the aerodrome has no stop bars or taxiway centreline lighting installed.

The standards in ICAO defines 4 levels of implementation for an A-SMGCS system based on the complexity of the airfield layout and traffic density:

A-SMGCS Level 1 (Enhanced Surveillance)

This level provides situational awareness of the aerodrome traffic through identification, position and tracking of aircraft and vehicles. This makes use of improved surveillance and procedures, covering the manoeuvring area for ground vehicles and the movement area for aircraft. The procedures concern identification and the issuing of instructions and clearances by air traffic control.

The system provides the following benefits to controllers:

• Provides a visual display of the aerodrome traffic independent of vision capability of controller to see the traffic element.
• Provides the position of the aerodrome traffic irrespective of visibility conditions
• Allows the controller to anticipate situations that can result in collisions between aircraft and aircraft/vehicles, especially in conditions where visual contact cannot be maintained.

A-SMGCS Level 2 (Surveillance + Safety Nets)

At this level, further safety systems are added that are designed to protect runways and designated areas. Level 2 contributes to airside operations as a safety improvement, enabling controllers to prevent hazards/incidents resulting from controller, flight crew or vehicle driver errors or deviations. Alarms are created in the system to assist the controllers in identifying in case of conflicts between all vehicles on runways and detecting the incursion of aircraft onto designated restricted areas. These alarms can be configured to provide audible alerts to the controllers to assist in rapid action to detected conflicts.

A-SMGCS Level 3 (Conflict Detection)

Level 3 involves the automatic detection of all conflicts in the movement areas as well as a routing service which generates a route for each aircraft/vehicle based on known aerodrome parameters and constraints or following an interaction by the controller. The routing and planning offered by the system is semi-automatic, where possible guidance routes are suggested by the system to be manually accepted/ confirmed by the controller. Before the aircraft or vehicle starts moving or in the case of an arriving flight before landing, the system generates a route proposal based upon the operational situation (Runways and Taxiways in use), and information provided into the system by other external sources. When the controller authorises the aircraft /vehicle to start moving on the movement area the route status changes to ‘cleared’ upto the clearance limit unless the controller has modified it. Due to operational events the controller can modify either a planned route or a cleared route.

A-SMGCS Level 4 (Conflict Resolution, Automatic Planning & Guidance)

Level 4 A-SMGCS provides automatic planning and guidance and provides resolutions for all conflicts. It provides a system of automatic routes for pilots and controllers, usually implemented with a follow –the- green taxiway lighting system where vehicles and aircraft follow the automatically selected route and hold position at the appropriately illuminated stop bars. To generate a planned route the routing function needs to know the start and end point. These are usually the assigned runway and parking stand for aircraft or for vehicles are two positions on the movement area. Known rules and aerodrome constraints such as the category of taxiway vs the type of aircraft or the assigned take off runway are all considered by the system when generating the route. Any new airfield restrictions that occur such as a taxiway closure or change of runway in use should be considered by the routing module to update the planned and cleared routes. As is the case in a Level 3 system, due to operational events the controller should be able to modify either a planned route or a cleared route.

Surface Movement Guidance Control System

An SMGCS control system is designed to enable an aerodrome to operate safely in the intended conditions. The system should be designed to prevent collisions between aircraft, between aircraft and ground vehicles, between aircraft and obstacles, between vehicles and obstacles, and between vehicles. An essential safety function of an SMGCS system is to safeguard against unauthorised and  inadvertent entry onto operational runways by aircraft and vehicles.

An SMGCS system consists of the provision of guidance to, and control or regulation of, all aircraft, ground vehicles and personnel on the movement area of an aerodrome. Guidance relates to facilities, information, and advice necessary to enable the pilots of aircraft or the drivers of ground vehicles to find their way on the aerodrome and to keep the aircraft or vehicles on the surfaces within the areas intended for their use. Control or regulation means the measures necessary to prevent collisions and to ensure that the traffic flows smooth and freely.

An SMGCS system comprises an appropriate combination of visual aids, non-visual aids, procedures, control, regulation, management and information facilities. Systems can be simple at small aerodromes with a low traffic density operating in good visibility conditions, to the complex systems required at larger aerodromes operating in Low Visibility conditions. During Low Visibility operations, adequate visual cues to pilots and vehicle operators are necessary to maintain their situational awareness and to ensure continuation of safe, efficient ground operations.

The key elements of SMGCS are the enhanced visual aids which include taxiway centreline lighting, markings, and signage, stop bar lighting, runway guard lights, along with the provision of visual cues for vehicle operators. In airfields operating at high traffic density levels at low visibilities it usual for the lighting visual aids to be supplemented by Surface Movement Radar (SMR) which provides the controller with continuous information on runway occupancy and taxiway usage.

The SMR can make a valuable contribution to the safety and efficiency of surface movement control at night and in times of poor visibility. Although the SMR can provide positional information to a controller, it is very difficult for the controller to position an aircraft accurately using such radar, hence the need for the enhanced visual aids on the airfield so that pilots of aircraft and drivers of vehicles can comply with controller instructions. As such the SMR should be considered as one component of the SMGCS system to be used in conjunction with the illuminated visual aids.

Modular Control System

The Modular Control System is a push button hardware system known to have controlled airfields both RAF and Naval, in the UK and at overseas bases. The MCS has undergone many changes and alterations during it’s existence, one being the inclusion of control of constant current regulators (CCR) to power taxiway circuits which was previously achieved by the use of a ‘D22 contactor unit’ and a Transformer Mains Supply Electronic (TMSE).