The datalink weather revolution: safer and less stressful flights

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Do you ever feel like Mother Nature reads your flight plan, then carefully moves the worst weather right over your destination? I’m no conspiracy theorist, but the idea seemed plausible to me as I cruised home on a trip last week. For 700 of the 750 miles we covered that day, the weather conditions were quite good, with nothing more than a thin cloud layer below and a smooth ride on top. Unfortunately, the last 50 miles featured a fast-moving winter cold front with multiple lines of rain, some thunderstorms, and very gusty winds. Not wildly unsafe, but also not the type of thing that’s fun to descend through with a planeload of passengers.

Twenty four hours before takeoff, the prog chart made it clear this flight would be a race, and it turned out to be exactly that: could we land before the line moved through and turned a 55-degree VFR day into a 25-degree IFR night? I thought the answer was probably yes if we left on time, but neither our passengers (who showed up late) nor Air Traffic Control (who generously provided us with a 25-minute ground hold) seemed to get the memo. Passengers are allowed to be late—it’s why they love general aviation—but I think Boston Approach may have been on Mother Nature’s team that day. Have I mentioned conspiracies?

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The race is on, but at least you know what you’re getting into.

After taking off nearly two hours late, we settled in to enjoy a 65-knot headwind and started calculating our estimated time of arrival. Based on the latest TAF, it looked like our airplane and the cold front would make it to Cincinnati at exactly the same time. That was disappointing given my careful planning the day before, and yet I found myself completely at ease with the situation. I looked at my iPad and had a god’s-eye view of the weather situation, including radar, satellite, METARs, and PIREPs. I knew where the worst weather was, how fast it was moving, and what my Plan B and C would be if things went downhill.

I put the iPad down after a few minutes and said to the other pilot flying with me, “we’ll just keep going and see how that line develops as we get closer.” I suspect that’s a common phrase for many Air Facts readers who fly cross countries—and indeed, this was just another day at the office—but that doesn’t make it any less miraculous. Quite simply, datalink weather has changed how we fly. Used properly, it can make general aviation much safer. More than that, though, it can remove some uncertainty, making longer trips more comfortable and less stressful. I know it did for me last week, and it made me appreciate the tools we have.

I’ve been a pilot for 27 years, just long enough to experience the revolution in weather technology. And what a revolution it has been: consider each generation of technology, and how it influenced our flying technique.

Flight Service

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Datalink weather, version 1: Flight Watch.

When I first started flying, weather avoidance basically meant Flight Watch or Flight Service. If the clouds up ahead looked ugly, the only option was to leave ATC for a few minutes and talk to a specialist. These people meant well, but listening over a scratchy radio while they described a fast-developing cell was usually an exercise in frustration: was it 30 miles east of Boiler VOR or Brickyard VOR? Or was it 30 miles wide? Or was it moving 30 miles per hour? How do I listen over a VOR, anyway?

For the flight above, I probably would have called Flight Watch every half an hour for an update, furiously scribbling notes and trying to draw the line of rain and storms. I would have been unable to pick up AWOS broadcasts hundreds of miles out, so I wouldn’t have had the granular understanding of the front’s movement I had by continuously monitoring how the front influenced METARs. And I would not have had the precision to know where the PIREPs and lightning strikes were with respect to my route. Without datalink weather, I might have even landed short to take a look at the radar in the FBO lounge before flying the last 100 miles.

On-board lightning detection

My first experience with a lightning detection device came courtesy of a salty old instrument instructor I once flew with. As we bumped along in the clouds one day, he pointed to the old Cessna 300 ADF in the panel: “just watch that needle—it’ll point to the lightning.” Sure enough, every once in a while the needle would snap from its straight-ahead orientation to a 90-degrees-right orientation. This seemed too good to be true: the ADF could pick up baseball games and lightning! Who needs LORAN when you have that kind of technology?

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Stormscope can tell you there’s convective activity, but range is mostly a guess.

After I earned an instrument rating, I started flying a Cessna 172 with a very old Stormscope and realized the ADF trick was just that, a trick. The Stormscope was invented in 1975 and the model I flew with in the late 90s looked like it was the first version, but it still offered a useful display of nearby storms. Short of onboard radar (which I thought was an exotic tool reserved for airline pilots), this round screen was the only way to get near-real time weather information in flight. In particular, it showed the most dangerous threat: convection.

Stormscope was a major advance for light airplane pilots, and it still has value today, but it has limitations. For one, it does a poor job of plotting the exact location of strikes. While the azimuth is usually reasonably accurate, the range often isn’t—stronger cells show up closer than they really are. Secondly, Stormscope doesn’t tell you anything about in-flight icing, wind speed, or surface weather, and all of those were important on my flight home to Cincinnati last week. In fact, the airplane I was flying has a Stormscope installed, but I never looked at it on this flight. I had better options.

XM weather

Datalink weather had been discussed since the 1970s and commercially available solutions were gaining popularity by the late 1990s, but it was the launch of the Garmin GPSMAP 396 in 2005 that really changed the game. Finally, pilots could get near-real time radar images in the cockpit—and on a portable device! That avoided expensive panel work and unlocked datalink weather for renters and flying club members who didn’t control their panel avionics.

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The Garmin GPSMAP 396 was a revolutionary product in 2005.

Avweb’s Paul Bertorelli wrote at the time, “I think Garmin will sell the heck out of this thing. If anything, buyers may be irritated due to short supplies at OSH.” He was absolutely correct. I was working at Sporty’s then, and I remember a palpable excitement among customers—the 396 was one of the most significant product launches I’ve been a part of in my 23 years in retail.

I flew with the 396 and its successor, the GPSMAP 496, for many years, including some hours when I was trying to impersonate Richard Collins by flying a Cessna 210 in all kinds of weather (boy did he made it look easy). These portable GPSs were invaluable and gave me the confidence to make some trips I wouldn’t have otherwise, but they were still somewhat hard to use. The 396’s screen was less than 4″ diagonally, which pales in comparison to my iPad Pro’s 12.9″ screen today. The user interface also required lots of button pushing, so it was a challenge to get a big picture view of the weather. Radar was easy to see, but details like PIREPs and AIRMETs could be a challenge. And that’s not to mention the price. While the 396 definitely made datalink weather “more available,” the $2700 purchase price (over $3800 today!) and $50/month subscription wasn’t cheap.

Of course XM Weather is still around today (now called SiriusXM Weather, after a merger of rivals a few years back), and I used it extensively on my flight home from Boston. The list of available weather products has expanded over the years, but the basic promise is the same: a continuously updated view of all important weather reports, one that requires no special skills to interpret (like onboard radar). That means weather flying in light airplanes is now mostly about strategic avoidance, making deviations many miles ahead of time, instead of picking your way through cells.

ADS-B and iPads

Seven years after Garmin changed the industry with the 396, another product brought datalink weather to even more pilots. By 2012, the FAA had been working on its ADS-B system for many years and had teased the idea of subscription-free datalink weather as an incentive for pilots to equip. But it wasn’t until Apple’s tablet computer, some radical thing called iPad, found its way into general aviation airplanes that ADS-B weather (technically called FIS-B) finally took off.

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The original Stratus ADS-B receiver launched a whole new category of portable avionics.

A slew of devices, beginning with Appareo’s Stratus and quickly followed by Garmin’s GDL series and later ForeFlight’s Sentry, offered less expensive hardware (70% less than that original Garmin 396) and no subscriptions. For pilots who were already flying with apps like ForeFlight, a portable ADS-B receiver was a slam dunk, and tens of thousands of pilots added it to their list of must-have gear.

Besides the FAA weather, the other key innovation was the electronic flight bag apps that displayed this new datalink weather stream. Instead of the Garmin’s small screen and rocker buttons, the iPad offered a large, vivid screen with intuitive touchscreen controls. If you wanted to zoom in on a line of weather, you just pinched your fingers. If you wanted to learn more about a SIGMET, you just tapped on it.

This seems like a small change, but it affected how pilots fly in important ways. One example most pilots take for granted these days is rubber band flight planning. As we approached Cincinnati last week, I was able to quickly compare possible deviations by simply dragging my course line until it was clear of the worst radar returns. In less than five minutes, I had backup plans, complete with updated time en route and fuel burn numbers. Deviating south looked better, since it was 10 minutes less flying time, but also because it was on the backside of the weather—the animated radar, another benefit of datalink weather, clearly showed the rain moving northeast. This is actually a complicated flight planning problem, but iPad apps make it easy.

Electronic flight bag apps are also great at seamlessly displaying multiple weather reports at once. It’s helpful to look at radar, but when that’s combined with cell tops, PIREPs, and METARs, you can make much smarter decisions. In my case, all this information suggested the south side of the line of weather had high cloud bases and a relatively smooth ride, with nothing more than moderate rain. I could have figured this out on a small GPS screen, but it was much faster on my iPad. The fact that my active route, including a STAR, was synced from the panel and overlaid on the map was just icing on the cake.

Some things never change?

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As good as datalink weather is, the view out the front window is still unbeaten.

My flight from Boston to Cincinnati ended up being a non-event. We flew through some moderate rain, but as expected we barely had a bump and were below the clouds for the last 10 minutes. It was a routine flight, devoid of stress, nervous passengers, or frantic deviations. All we had to do was monitor the weather from hundreds of miles away, make a plan, and update it based on the latest information. It’s the same thing that happens hundreds of times per day, all across the country.

No doubt there will be more innovations in datalink weather. Perhaps in five years we’ll all be looking at 1-minute old radar that’s presented in 200-colors, complete with high definition 3D scans of the atmosphere. Maybe we’ll get LIDAR-derived turbulence warnings or sophisticated icing forecasts based on downlink from airliners. But even if that doesn’t happen, the tools we have today make cross-country flying easier and more reliable.

That’s no reason to forget the basics, though. Richard Collins’s first rule of weather still applies: “what you see is what you get.” That’s a reminder that the pilot’s view out the front window is still the best weather tool, and no amount of technology can make a thunderstorm safe. Sure enough, I spent a lot of time sizing up the clouds on our arrival into Cincinnati, but I felt a lot better knowing what the radar looked like on the other side.

I’m old school at heart, but I don’t leave the traffic pattern without datalink weather.

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