Waypoints

Editor in Chief Thomas B. Haines owns a Beechcraft Bonanza for personal and business flights.

My prediction didn't quite come true. With a newly installed Garmin GDL 69 weather datalink receiver in my airplane, I was convinced that the trip to EAA AirVenture this year would be weather free. A benign trip to and from the big show in Oshkosh would be a first. Never in more than 15 such trips has that 575-nautical mile journey in late July not provided challenging weather in at least one direction.

Ten days out, the weather forecast for our departure looked terrific. Even three days in advance, the forecast called only for the chance of a little rain for a few hours. But by the day before departure, a long cold front had draped itself all the way from Lake Erie to Texas, causing severe storms throughout the Midwest and promising the same for the afternoon on the day of our departure. Let the adventure begin! After all, what would we all talk about at AirVenture if it weren't for the challenging weather we faced getting there?

Gear to go

The GDL 69 receives data from the XM Satellite Radio satellites and displays the results on a Garmin GNS 400- or 500-series navigator, the AT MX20 multifunction display, or the G1000 integrated cockpit; in my case it's a GNS 530. The weather data are provided by WxWorx, an Alabama-based company started by Bob Baron, who probably knows more about capturing and displaying weather data than just about anyone.

The GDL 69 computer is installed in the rear of my Beechcraft Bonanza and connected to a small puck-size antenna on the top of the airplane. WxWorx provides a constant stream of data to XM, which transmits it through its satellites — the same high-powered pair (named Rock and Roll) that delivers tunes and talk to millions of satellite radio subscribers. Ask me five years ago who would pay $10 a month for commercial-free radio and I would have said no one. If you need additional stock tips, just buy all the stuff not in my portfolio.

The GDL 69 computer processes the stream of weather data and pipes it up front to display on the GNS 530. The 400- and 500-series systems can display Nexrad radar images and text and graphical METAR information. WxWorx provides a host of additional weather products, including lightning data, satellite mosaic, graphical sigmets and airmets, terminal area forecasts, temporary flight restrictions, storm cells, cloud tops, forecast winds aloft, and others. However, according to Garmin's Tim Casey, the processors in the 400 and 500 systems are completely maxed out, allowing for display of a limited number of products. The MX20, G1000, and, ironically, the new GPSMap 396 handheld can display the entire Chinese menu of products. WxWorx has arrangements with a number of other companies where its range of weather products can be shown on various multifunction displays, handheld computers, and personal digital assistants.

But in choosing what to show on the limited resources available on the 400 and 500 products, Garmin hit a home run. Fly with it for a while and you'll not want to take off again without Nexrad. Need to know the weather at your distant destination or airports along your route? The METAR for any airport is only a few knob twists away.

Into the wild gray yonder...

Shortly after takeoff from Frederick, Maryland, for our trip to Oshkosh, the GDL 69 was showing the line of rain showers associated with the front some 250 miles to the northwest. Our early morning departure meant we would likely only be facing rain; the convection near our route was not forecast to begin until the afternoon. However, farther to the southwest, the front was kicking up big boomers even at dawn.

With AOPA Pilot Editor at Large Tom Horne in the right seat and Executive Editor David Robb in the back, we ventured around the southwestern corner of Pittsburgh and headed toward Toledo where the Nexrad showed we would first encounter the rain. Throughout the trip, the Nexrad images were never more than nine minutes old and usually about a maximum of only four minutes old, as shown on the 530's screen. In truth, the information is actually about five minutes older than that — the time it takes the data to be scooped up by WxWorx, processed, and sent through the XM system to the airplane.

A direct route to Toledo and then up toward Detroit would take us through a rather large area of light to moderate rain, as shown by the green and yellow radar data on the moving map. The Nexrad data — along with Stormscope data if available — can be overlaid with the route on either of the 530's two moving-map pages. On the dedicated Weather page, Nexrad and Stormscope data can be shown individually or together. Another choice from the Weather page is graphical METARs, which use color-coded vertical and horizontal bars for each location to show whether the ceiling (vertical bars) and visibility (horizontal bars) are VFR, marginal VFR, IFR, or low IFR. It's easy to tell at a glance whether the weather ahead is VFR or IFR and why. Other pages show the surface winds for each location in a graphical format — traditional wind barbs — and temperature/dew point. Overlaying Nexrad and Stormscope makes for a powerful situational awareness tool.

Rather than direct Toledo, the better choice based on the Nexrad image seemed to be a slight turn to the west toward Findlay, Ohio, and then a turn to the north toward our planned stop at Fulton County Airport in Wauseon, Ohio, for fuel. Air traffic control cooperated nicely. As we neared Findlay, the next Nexrad update showed the rain arriving right over the VOR, so we made our turn to the north early and shot through a gap in the showers with the airplane hardly getting wet.

A check of nearby METARs showed the weather at Fulton County as marginal. However, Lansing, Michigan, was reporting VFR so we changed our destination and flew an easy approach there for fuel.

We made these in-flight decisions on this dynamic weather day without having to talk to flight watch and without a fear of the unknown ahead. Between the Stormscope and Nexrad we could see what was ahead and make decisions well in advance to help us steer clear of trouble. The METAR data added to the picture.

After oohing and ahhing about the preciseness of the images and with the weather behind us, Horne and I philosophized about the impact of weather datalink on general aviation flying. It is arguably as big of an improvement to our flying as was GPS. GPS driving a moving map provides amazing situational awareness. Now add Nexrad to the picture and a great deal of uncertainty is removed from flying. With the information, I can see pilots getting a great deal more utilization out of their airplanes. Sure, a few pilots will cut the corner too close and find themselves in trouble, but that happens anyhow. Those who understand that datalink weather is for strategic decision making, not tactical decision making, will find it a great comfort in the cockpit. Had the Nexrad been showing red, for example, or if lightning was nearby, we would not have flown through the gap in the showers.

As it is, though, datalink weather holds the promise of safer flying and more flying as pilots feel more comfortable venturing out when they have the entire weather picture available to them.

The details

A GDL 69 lists for $4,995; expect to spend about another $2,000 for the installation, depending on complexity. The data subscription through XM is $29.99 per month for the Aviator Lite group of products, which is all the 400/500 owner needs given the limited number of products that can be displayed. Those who can display a greater number of products can choose the Aviator option, which runs $49.99 a month. The GDL 69A allows the pilot to also listen to XM Satellite Radio news and entertainment. The 69A costs $5,775 and adds slightly to installation costs. XM charges an additional $10 a month for the entertainment package.

If you don't mind a lot of wires in the cockpit, an alternative can be the GPSMap 396 handheld with an XM input. The GPSMap 396 handheld lists for $2,695; look for a full report on this new product in an upcoming issue of AOPA Pilot.

Links to additional information about datalink weather and weather flying may be found on AOPA Online ( www.aopa.org/pilot/links.shtml).

E-mail the author at [email protected].