Aviation In Canada

Tuesday, January 11, 2005

GPS in Aviation

I attended a seminar last evening on GPS and aviation, hosted by the knowledgable George Dewar. He's a long time GPS wizard with a background of an inspector with Transport Canada since 1993 who moved to NavCanada to begin designing GPS approaches (with the first two stand-alone GPS approaches in Canada being RWYs 14 and 32 at Saint John, NB - CYSJ). He has been involved in outside projects as well, giving him a good base knowledge level and plenty of surveying experience.

The ILS is protected as the primary precision approach NAVAID by ICAO until 2010. After that, we're going to see some changes. First off, the current GPS platform is pretty darn accurate already, the issue is one more of integrity. With 30 satellites in orbit (GPS only requiring 21 for coverage), availability isn't a problem, either. But the concept of starting a GPS approach to CAT I ILS minima only to have it complain of poor satellite signal quality is not a good thing if all you have is GPS. Satellite health suddenly changing, geometry not working out, etc. All of these issues remain to be tested and proven, as some carriers are now in the process of doing. For this reason, GPS still is not classed as a "sole means" method of navigation for IFR flight.

Over the coming five years, GPS will find its way more and more into our flying lives, and eventually there will be no more ILS system installations. Newer avionics will be capable of handling enroute, terminal and approach phases of flight without the need for ground-based NAVAIDs. Of course, there will be many aircraft who don't have GPS, so current ILS systems will continue to be maintained for some time. Nobody needs to look for a new job just yet. The aviation industry has historically been quick to look at new ideas but slow to implement them and even slower to remove the old when it's obselete.