ATM Modernization, Business & GA, Commercial, Military

Editor’s Note: A Fresh Look at the Grid

By David Jensen | February 1, 2000
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In last month’s issue, we covered the IFR Global Positioning System (GPS) "grid" used by the offshore support helicopter operators in the Gulf of Mexico. As mentioned in Rick Oeder’s story (page 32), the so-called grid concept for navigation and surveillance allows helicopters to fly virtually direct, point-to-point, and it gives the controllers at the Houston Air Route Traffic Control Center (ARTCC) the ability to separate IFR aircraft in a non-radar environment. In short, it appears to be a win-win arrangement.

But could it, with its Free Flight similarity, be applied on a larger scale? The possibility is being considered.

On Nov. 4-5, the U.S. Federal Aviation Administration’s Southwest Region came to FAA headquarters in Washington, D.C., to brief the agency’s ATA 200 office of the grid system’s one year of operation in the gulf. ATA 200 is part of the Air Traffic Airspace Management office, dedicated to making the National Airspace System (NAS) more efficient. To that end, ATA 200 largely performs the planning and analysis functions.

During the November meeting, officials from the Southwest Region were joined by those from the New England Region, where a grid-like system has been under study but not implemented. New England’s program is called SNARS, for Satellite Navigation Aviation Reference System.

How might the grid system appear within the NAS? With "greater granularity," was the short response of an FAA spokesman. He elaborated by saying that currently, each ARTCC develops points in the airspace, called "fix posting areas," which allow the automatic handoff of aircraft from one center’s control to another.

"But there are problems," he adds. "The points don’t always agree [between two centers] and then you have to revert to a manual handoff."

With a grid system such as that in the Gulf of Mexico, there simply would be more points (hence, more "granularity")—and the points would be universal, i.e., recognized by all ARTCCs. Automation would proceed, uninterrupted. Controller workload would decrease. With the grid’s identifiers (like, say, OH45, indicating an Ohio destination at the 45th point), controllers could even approximate flight trajectories. Flight plans would be more point-to-point. An ideal system, right?

We’ll have to wait an see. "We don’t know what form the grid system might take," says the FAA spokesman. "It may be like SNARS or like the one in the gulf or it might be a hybrid of those systems.

"We don’t as yet have sufficient data on how the grid system works in IMC [instrument meteorological conditions]," he adds, explaining why the FAA has not been quick to adopt the system. More study obviously is required.

Still, with its apparent benefit both to operators and controllers, as well as its potential to spawn even better solutions to our air capacity dilemma, the grid system remains the one to watch closely.

E-mail comments or questions to djensen@pbimedia.com

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