Bits and Pieces
Whither ADS-B (in Canada)?
By Ian Brown, Editor – Bits and Pieces, EAA 657159
Okay, maybe whither is an old word. Maybe a more current term might be “ADS-B, wassup?” Will automatic dependent surveillance-broadcast (ADS-B) be causing concern among the low-altitude GA pilot throng in Canada, or can we relax? The implementation of 406 megahertz emergency locator transmitters (ELT`s) is still causing stress among the GA fleet. Much has been written about it, and the expense is an extra burden. What’s the impact of ADS-B on the GA owner-pilot?
In my correspondence with John Michael Fleming, an operations specialist with Nav Canada, I asked about the difference between what I’d found described as multilateration (MLAT) and ADS-B. I learned that multilateration produces a much cheaper way to cover remote areas than secondary surveillance radar (SSR). MLAT is commonly used in civil and military surveillance applications to accurately locate an aircraft, vehicle, or stationary emitter by measuring the “time difference of arrival” (TDOA) of a signal from the emitter at three or more receiver sites, with resolution benefits from more than four receivers.
I was surprised to learn that the Czech Republic is recognized to be a technology leader, having implemented MLAT successfully in 2002. If you’re interested in the technology, then check out www.Multilateration.com for some fascinating reading. You can think of multilateration as a ground-based network of stations capable of collecting all the transmissions from the existing transponders or ADS-B and figuring out where a specific target is and where it’s going. The only difference on a controller’s screen will be that the rate at which the target is updated is faster than an SSR target.
Multilateration sites will facilitate the deployment of ADS-B by providing the data flow from ADS-B to the ATC system. The cost of equipping all the flying aircraft with ADS-B is the major hurdle and likely to dictate the rate and method of deployment. Obviously the more an aircraft operator will gain, the more rapidly he’s likely to adopt ADS-B.
The Nav Canada website makes it plain that the early focus for ADS-B will be on large areas with poor radar coverage, like the far north, and at the highest flight levels. For the moment, large aircraft will be required to have ADS-B for flight levels 350 to 400 in the airspace over Hudson Bay. Eventually all flight levels above 290 will be required to have it in the north and probably the Atlantic seaboard.
Benefits of ADS-B for airlines include significant fuel savings, expedited flight routing, and reduced separation minima. For the moment, if you don’t need oxygen for your flight it looks as though you can breathe easily.
For more information, see the Nav Canada brochure.