Plane & Pilot
Tuesday, December 7, 2010

The Evolution Of Navigation


Flying from A to Z is no longer as simple as it used to be. It’s simpler.


When I was finally handed off to Shannon Radar at what should have been 175 miles west of Shannon, the Irish controller came back and reported, “Radar contact at 177 miles, three miles south of flight plan.”

I couldn’t believe it. All I’d been doing for the previous 10 hours was rotating the bug to the new heading every 80 minutes and letting the autopilot hold me on course. It seemed inconceivable that dead reckoning had actually WORKED.

The other day, as I was monitoring the readout of the Garmin 696 in my Mooney, I had to reflect on how far we’ve come. I’ve been fortunate to use a variety of GPS units from Magellan, Trimble and Garmin over the last 20 years, and I’ve been constantly amazed at their capabilities. Who would have guessed in the mid-’60s that we’d someday have a universe of satellites orbiting overhead that could pinpoint our position in three dimensions to an accuracy of a few feet at refresh rates of five times a second?

At its core, that’s all any GPS receiver does, derive a position. Despite the complexity necessary to generate position resolutions, GPS is an incredibly simple method of determining position. All other functions are mere applications of long-standing computer technology.

Today, GPS is accepted as the standard method of navigation for the military, general aviation and even many of the airlines. Inertial nav was once the airlines’ dominant form of maintaining a course for long-range navigation, but GPS is rapidly displacing inertial from the cockpits of airliners worldwide.

The Garmin 696 is unusual in that it’s the largest and most expensive portable GPS on the market, but perhaps appropriately, it’s also the most talented, and it’s almost silly-simple to use. The model was introduced two years ago at Oshkosh, and despite a list price of $2,995, the system continues to sell remarkably well.

Aircraft navigation has realized amazing improvements in the short span of a single century, from dead reckoning and pilotage in the first 50 years of powered flight, to ADF/VOR in the next 30 years and now to GPS in the last 20 years.

GPS is, by far, the most accurate and intelligent navigation system ever offered for general aviation consumption.

But dead reckoning was more fun.



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