With air traffic set to grow annually in the Middle East by 7.7 percent, the provision of state-of-the-art air traffic control at both local and regional levels is vital to maintain safety and improve on-time dispatch figures. This is particularly important in regions of heavy traffic, such as Dubai. As one of the world’s foremost air traffic management system experts—the company claims that one in four flights worldwide benefits from its systems—Saab is implementing key elements of the Dubai region’s air traffic system.
Earlier this year the company won contracts to provide multilateration networks at both Dubai International (DXB) and Dubai World Central (DWC), covering both surface and wide-area airspace monitoring.
Multilateration works by a small ground unit transmitting to an aircraft’s transponder, which then returns a signal. By using time-of-arrival information from three or more separate ground units the aircraft’s position can be plotted to within seven meters.
In the wide-area application the systems at DXB and DWC can draw on information from the same ground unit network, representing the world’s first example of a dual-site installation.
Both airports are also receiving a surface multilateration system. This works in a similar fashion to plot aircraft movements on the ground. Airside vehicles can also carry transponders so that their movements can be integrated with those of aircraft. Typically a runway area employs 18 to 20 ground units to provide full coverage, whereby three units must have line-of-sight to ground vehicles with one redundant unit always available to cater for failure.
The benefits of using multilateration over radar are a quicker refresh rate—every second rather than every five or so for a typical radar—and the ability to place the ground units wherever they are required. The ease with which they can be placed or relocated elegantly accounts for the ever-changing building landscape of the modern airport. However, only the vehicles and aircraft that carry transponders can be tracked, meaning that surface radars are still required to detect and track non-cooperative targets such as animals, people or errant vehicles in crucial areas such as on and around the runways.