Last spring, Garmin made a declaration of sorts. It introduced an aggressive new line of inexpensive avionics for experimental aircraft. This said, in effect, even 800-pound gorillas have to compete in a new market where avionics prices are dropping, due in part, to pressure from tablet computers and ever-more-capable apps.
Within two weeks of Garmin’s anno
uncement, the cheap apps wave built ever higher with the introduction of three portable devices that offer impressive EFIS displays for iPad and Android platforms. At Sun ‘n Fun, these gadgets were being snapped up like candy and pasted to glareshields everywhere, promising EFIS displays, weather on the fly and traffic, too.
But do they really deliver all this? Yes, but right up front, we’ll sprinkle some rain on the parade. Clever as they are, these new portables aren’t the instrument systems—or even backups—of your dreams.
These three ADS-B/EFIS products appearing within weeks of each other resulted from a rare confluence of events. The enthusiastic uptake of tablets by pilots is one, but another strong driver is the FAA’s rapid build-out of the ADS-B ground network at the same time that Mitre Corp.—a federally funded R&D lab—developed a licensed receiver technology for ADS-B. This enabled a spike in development of ADS-B portables.
The three latest—Sagetech’s Clarity and Clarity SV, Appareo’s Stratus II and Levil’s iLevil—contain the ADS-B receiver, plus tiny AHRS chips called MEMS (micro-electro-mechanical systems) whose output, when displayed on a tablet, mimic the look and feel of certified EFIS systems. At prices ranging from $899 to $1400, what’s not to like?
We obtained a sample of each of these devices and wrung them out during several short test flights in a Cessna 150 and a Cub LSA. All of them are battery powered, so no ship’s voltage is required.
What They Do
All have similar features, with ADS-B receivers and the AHRS added on. All three also have WAAS GPS engines which communicate position to the apps. The Sagetech Clarity SV ($1400) is the smallest, measuring only 2.5 inches square by 1.5 inches high. It fits easily on the glareshield in a sticky gel pad meant to hold it fast. (It doesn’t always.) The Clarity’s lithium-ion battery is claimed to last for six to eight hours. The Clarity provides ADS-B traffic on two frequencies—978 and 1090 MHz—and this, along with the AHRS data, is transmitted to the tablet via a dedicated wireless network.
The Clarity feeds its data into at least six different apps. We tested it with WingX Pro, which can be configured to display the EFIS on a split screen or the entire screen and allows some degree of customization. You can pick a plain AI display, for instance, or—unique to the Clarity SV—an EFIS display with limited synthetic vision features.
Levil’s iLevil ($1195) also works with WingX, plus the company’s in-house utility app. More app compatibility is planned. The iLevil has a rectangular form factor, 4 inches long by 2.5 wide and 1 inch high. It sports a little whip antenna and has a small solar array atop the chassis to extend the battery charge, which the company claims is three to four hours. The iLevil tracks only 978 MHz targets, so in a product category that’s already traffic limited (no ADS-B out), the iLevil is more so.
You’re on your own to mechanically mount the iLevil; there’s no gel pad option. A robust strip of Velcro will do it and this is necessary because if the thing comes lose, there goes your attitude reference.
Last, the $899 Stratus II is the price leader among these products. The original Stratus appeared about a year ago, the cooperative effort of device maker Appareo, ForeFlight and Sporty’s, which sells it. It’s the largest of the three, at 6 by 2.6 by 1.25 inches and it comes with a gel pad for glareshield mounting. But once again, we didn’t find the mount very reliable. Sometimes it grips, sometimes it doesn’t. Claimed battery life for the Stratus is up to eight hours.
Unlike the others, however, the Stratus requires its own dedicated app, a freebie from Appareo called Horizon. It runs only on the Apple IOS platform and it doesn’t run within ForeFlight, so you have to close that, then fire up Horizon. The other two products, running WingX Pro, don’t require that.
Do They Work?
In a word, yes, and really quite brilliantly. Once powered up and stabilized on the glareshield, the wireless networks appear in the tablet settings menu. It takes under a minute for the devices to find themselves with GPS and to determine which way is up. Once that’s done, the tablet will display a correctly oriented EFIS.
“Correctly” is used advisedly here, because if the AHRS aren’t relatively level to begin with, they’ll show a slight bank or pitch indication from the level position on the ground. Each of the products deals with this in different ways.
The Clarity SV compensates for slight errors and finds level, correcting itself, but in WingX Pro, there’s also a cage and reset tab that can calibrate the display to level on the ground or in flight. Appareo’s Horizon app has both a straight-and-level button that instantaneously tells the device it’s in level flight and a manual adjustment so you can bump the pitch up to accommodate a taildragger’s nose-high stance on the ground.
The displays themselves mimic a full-blown EFIS, with airspeed and altitude tapes and a blue-over-brown AI representation. Since all three units have magnetometers, they also display heading. Note, however, that displayed speed is GPS groundspeed, not indicated airspeed and altitude is GPS altitude above the spheroid, not pressure or MSL altitude. However, stretching the what’s-allowable-envelope to nearer the breaking point, as we go to press this month, Levil announced the iLevil-AW, a unit that has—you guessed it—actual air data input from the pitot and static systems. We’re not sure about the legalities of plumbed-in portables in certified aircraft, but the iLevil-AW will provide uncalibrated indicated airspeed and pressure altitude.
Once the AHRS in these products are calibrated, their response in flight is excellent. Pitch and roll indications keep up with the mechanical gyros even if the portables aren’t quite as liquid smooth as is a certified EFIS system. Similarly, heading indications on all three are solid and more than accurate enough to navigate by.
Here, the split screen of WingX Pro has an advantage over Appareo’s Horizon. In WingX, you can put the EFIS on one screen, a navigation map—or anything else—on another and navigate quite readily. In Horizon, you get only the EFIS and you’ll have to toggle from that app back to ForeFlight for additional functions.
The AHRS units are robust, to a point. They’ll easily tolerate steep turns and rapid pitch departures, but grab one and shake it—or drop it off the glareshield—and the sensors become very confused indeed. The Clarity SV is the least susceptible to this, but it’s not bulletproof. When attitude reference is lost, the displays are red-X’d.
Great Backup, Right?
For under a grand, plus the iPad and app, these things are the perfect backup we’ve all been waiting for, right? Definitely not and even the manufacturers say as much.
“Do I want to release this product for specific functions, as a primary instrument or even a backup where you’re depending on it? The answer to that is no,” says Appareo CEO Barry Batcheller. We heard virtually the same explanation in different words from Sagetech’s Kelvin Scribner. The problem isn’t so much the devices themselves—the MEMS chips are actually considered quite reliable—but the tablets and apps.
We experienced this first hand during our testing. On one flight, WingX Pro locked up and upon restart, it would only run for a second or two before quitting again. The only fix was to reload and update the app, which is something you can’t do in the air and wouldn’t want to do for an instrument you’re depending on.
The companies also told us they’ve seen problems in apps related to the underlying IOS or hardware issues.
So what are these things good for? “Maybe backup to the backup,” says Scribner. Or just for general reference when flying in IMC, if more reliable instrumentation is readily in view. All of the units do deliver FIS-B weather data, which includes limited NEXRAD, TAFs, METARS, winds aloft, NOTAMS and other products. While the NEXRAD is broadly useful, it’s not nearly as detailed nor as timely as is XMWX Satellite Weather’s product. But the price is right: it’s free. We would call the weather products useful for broad planning purposes, but nothing more. Also, ADS-B signals are usually not receivable on the ground.
As for traffic, the dual-frequency devices—Clarity SV and Stratus II—will see traffic directly broadcasting on the 1090 MHz extended squitter. That’s mostly airliners and a few GA airplanes.
If any aircraft around you is equipped with ADS-B Out—and that’s not many—the ground network will broadcast a nifty traffic package for that aircraft and you’ll see those targets. But you won’t necessarily see targets around your airplane, including Mode-C targets equipped with active traffic systems.
Bottom line: these gadgets aren’t of much practical help for traffic awareness.
Fifteen years ago—yes, that long—when database portable GPS appeared, we did the Boy Scout thing and advised against their use for navigation. Pilots ignored that advice and we eventually stopped giving it. The risk was simply too small against the benefits. But with these portable ADS-B/EFIS products, we think the risk is a good deal larger if you put too much faith in them as a go-to backup. They’re just not reliable enough, in our view.
If you insist, however, we would recommend having two platforms to run them—say the regular tablet and a smartphone running the same app. Second, fasten them to the glareshield with other than the gel pads. You don’t want them sailing around in turbulence.
The plausible reason to buy one may be mainly for the weather data—useful albeit limited—and a belt-and-suspenders backup for the real backup gyro you already have in the panel. Or maybe you just like gadgets; not that there’s anything wrong with that. There are worse reasons to buy cool stuff like this.
Paul Bertorelli, editorial director of Belvoir Media Group’s aviation division, is a closet gadget-geek. He lives to play with all the new cool toys.
Dynon D1 — Just EFIS
Dynon calls its D1 portable EFIS “Pocket Panel” and the name fits. The company introduced the D1 a year ago as a device leveraged from its popular line of non-certified avionics for the experimental market. As such, it follows a fundamentally different design strategy than do the app-based portable EFIS products.
The D1 is complete within a compact package measuring 3.6 by 3.2 inches and 1.16 inches deep. An internal lithium-ion battery powers the D1 for up to four hours, but it can also operate on ship’s power.
We tested the D1 in a Cub and an experimental RV8, with the unit attached to the panel with strong Velcro. Like some apps, the D1 has a calibration function so it can be sync’d to straight-and-level, unaccelerated flight in the air or on the ground.
But unlike the app-based EFIS products, the D1 is stable, using software similar to the well-tested code used in Dynon’s Skyview and other products, which are routinely flown in IMC. It has a MEMS-based AHRS engine but uses GPS to display GPS groundspeed, altitude and even rate information.
Does Dynon consider this non-certified, non-TSO’d instrument as a real-world backup instrument for a panel that’s otherwise legal?
“That’s essentially the designed use case,” says Dynon’s Michael Schofield. To the question of whether the D1 should replace an electric or vacuum backup gyro, Schofield says that’s up to the customer.
“Software stability is an issue. That’s why we decided to build a device that doesn’t rely on the iPad. Raw software reliability is going to be problem when you’re working in an ecosystem with wireless and Bluetooth and other apps,” he says.
At $1295, the D1 is competitive against the portables, although it is just an EFIS, with no traffic or weather component. But if all you want or need is AI backup, the D1 is likely a better choice than any of the tablet-based EFIS apps. —PB