Surface vehicles added to incursion-prevention program

 - May 4, 2009, 5:42 AM

Amsterdam’s Schiphol Airport is showing the world how to safely monitor and control the movement of surface vehicles and greatly minimize the risk of runway incursions.

Schiphol is Europe’s fifth largest hub, with five instrument runways, more than 100 airline gates and two separate but totally coordinated control towers that handle about 110 movements per hour. Last year the airport recorded nearly 430,000 flight operations.

Like most large airports, Schiphol operates an advanced surface movement guidance and control system (A-SMGCS, better known as A-Smiggs) to track aircraft surface movements and present that information on controllers’ screens. But the Dutch have moved far ahead of the FAA in the field of runway monitoring by including vehicles in the controllers’ picture. In fact, the airport now has more than 300 vehicles equipped with small mode-S transponders, each with individual short ID tags to differentiate them from aircraft. These vehicles range from crash/fire/ rescue, towing tugs and airport maintenance units to small vans used by wildlife specialists and runway friction engineers.

Not all airport vehicles are equipped. Only those requiring access to the “maneuvering” or operational side carry transponders; those restricted to the ramp areas, such as fuel and aircraft servicing trucks and pushback tugs, do not. But all vehicles have two-way VHF radios and are closely controlled.

To achieve this monitoring level, Schiphol employs two terminal approach radars, three surface movement radars and 21 multilateration mode-S “listening post” triangulation receivers strategically located around the airport. Data from these sensors is integrated and fed to flight data processing displays and runway incursion alerting systems in the two towers and to the airport’s collaborative decision-making partners.

The FAA is running late on surface vehicle monitoring, despite last year’s much vaunted runway incursion prevention program. No transponders are approved and, while a draft unit specification was published last year, there appears to have been little action since. One FAA concern was that too many vehicle transponders could overload aircraft mode-S transmissions and the agency proposed a 20-vehicle maximum, but Schiphol’s experience indicates that the low-powered beacons have a negligible effect.