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Features February 2014 Issue

Cockpit Weather Choices

Want AHARS With That ADS-B?

In addition to traffic, a deal-sweetener for some portable ADS-B weather systems is the addition of electronic flight instrumentation. We like to call these gadgets ‘glareshield candy’ because in general, we wouldn’t rely on them for take-to-the-bank reliability during a primary instrument failure in actual IMC. If you’ve used these gadgets you’ve probably discovered that the speed and altitude data is susceptible to lag and non-linear data display.

On the other hand, on a bad day it may be better than nothing, and for an additional crosscheck, they bring a certain level of utility. One portable system that tempts the boundaries of legality for certified aircraft is the $1395 iLevil AW. What’s unique about it is the ability to tap into the aircrafts pitot and static system, which adds actual pitot and static sensing for feeding the AHARS.

This means that instead of GPS-derived groundspeed, the iLevil can display indicated airspeed on Wing X Pro 7, Xavion and Levil’s AHRS utility. How good is it? Not quite good enough for sole means IFR, in our view. We evaluated it in the September 2013 issue of sister publication Aviation Consumer. While the airspeed data from the iLevil was linear, there were several dropouts that produced a red X on the display for a few seconds.

When it was working—which was most of the time—the iLevil AW data behaved like the airspeed indicator on any ADAHRS-driven EFIS. Its response is linear and free of the spikiness evident on tablet EFIS displays that rely on GPS groundspeed for an airspeed indication.

To read out indicated airspeed, you’ll need at least pitot reference pressure. The unit has an electrical connector for outputting serial data to feed non-certified panel mount equipment, and it will accept data input from the Zaon XRA portable traffic unit. (Zaon, by the way, went out of business while we were preparing this article.)

Although the AW is intended for experimental and LSA use, it could be possible to have it installed in a certified airplane that flies IFR. That’s the easy part. The hard part is finding a shop that is willing to sign off the pitot and static certification after they tap a non-certified portable into it. —LA

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