LVC Block Control on Airports without A-SMGCS

Many small and medium-sized airports in Europe and worldwide still have no A-SMGCS and do not plan to implement one in the near and medium-term future. This decision is usually based on the cost of such a system. Even the ‘base variant’, i.e. a Surveillance Function in combination with a display system displaying a synthetic surface traffic situation, constitutes a many million Euro investment. In addition, there are unavoidable expenditures in the areas of maintenance and further development over the entire period of use.

It is an official rule that controllers have to establish safe separations between the ground movements in Low Visibility Conditions (LVC), for example due to fog or heavy snowfall. This is a necessary regulation, since flight crews and drivers are no longer able to establish safe separations themselves due to the visual limitations. With an A-SMGCS, this is in principle possible even if there is no direct line of sight between control tower and the movements in the field. The synthetic surface traffic situation provided by the A-SMGCS can then be used by the controllers to issue adequate guidance instructions and to establish the needed distances between the mobiles. However, if there is no A-SMGCS at an airport, this is impossible and will result in a direct impact on airport capacity and delay.

On many airports without an A-SMGCS, the loss of direct sight between control tower and the mobiles on the aerodrome surface leads to a ‘one at a time’ principle in surface operations. Hence, departures will be delayed and arrivals will have to fly holding patterns in the air or to the alternate airport. In extreme cases, airports actually have to be closed completely due to fog or heavy precipitation. This leads to a perception of the airport as being ‘unreliable’ and will certainly have a negative commercial impact in the medium and long term.

To overcome this problem, MagSense Airport can be used on airports without an A-SMGCS to establish a cost-effective and reliable solution, which allows for valid traffic management procedures in LVC and without the costs related to an A-SMGCS. The solution is based on the established concept of "block control" in aviation. The concept is quite simple and divides the aerodrome surface into clearly defined areas and by means of MagSense Airport sensor chains. Any aircraft, tow movement or vehicle passing over a sensor chain is detected and the event is transmitted to a central system including a directional information. Based on this information, a simplified map-based situation display will then display to the controller whether an area is currently ‘vacant’, i.e. no mobile is currently in the area, or ‘occupied’. By means of this information, the controller can provide instructions to all movements that ensure there is always a vacant area (‘block’) between two movements. This keeps all movements at a safe distance from each other and allows to keep the airport operational in LVC and with more than just a single movement at a time.

This unique MagSense Airport-based solution is quite simple, not very expensive, and needs by far less maintenance and tuning compared to an A-SMGCS. Thanks to the Earth Magnetic Field Sensor’s unprecedented sensitivity, it is extremely unlikely, almost impossible, that a movement is not detected when passing over a sensor chain. This is not the case with other technologies, e.g. induction loops, which have e.g. a lot of problems in detecting vehicles with an increased ground clearance or a reduced amount of ferromagnetic materials due to modern lightweight construction.