ADS-B receiver & iPad combo: Early Impressions

Now that you've read all about what ADS-B in and FIS-B are, here are some screen-captures and commentary of my early experiences using it. Also: One piece of reference material that may be interesting if you're still learning that I forgot earlier: AIM section 7-1-11.

The setup I'm using is an Apply iPad (first edition), the SkyRadar ADS-B receiver, and either SkyRadar's own iPad app, or the Hilton Software WingX application. Which app to use is probably best left up to you: Both are available for free trial. After that, WingX requires a subscription fee, and the SkyRadar app requires a fee to update charts, but appears to continue to work afterward for free for displaying the ADS-B data.

In subsequent posts I'll get into discussing traffic (through TIS-B), data coverage, and some of the other quirks I've noticed. This post is all about the FIS-B data you can receive and how each app handles it.

The executive summary on which app is better for the FIS-B data is a toss-up: Neither support 100% of the data being transmitted, which is unfortunate. They get the most important bits, with WingX getting the edge for my vote in terms of organization of weather data. Because of these limitations my plan is to use WingX as my primary charting and weather display app, but will keep the SkyRadar app installed in case I need data I might be missing.

Over the past couple of months I've flown several trips with the setup, which is where I got the screen captures below. Most of the time I ended up using WingX, and have subsequently paid for an annual subscription. I'm going to skip describing the core features of each app in favor of concentrating on the FIS-B data. The WingX folks have some pretty good video documentation describing their product which you may want to view before purchasing their app, and the SkyRadar folks PDF documentation you can download.

NEXRAD (weather radar) is downloaded in 'strips'. You can overlay radar on any of the chart types (i.e sectional, en route IFR, topographic, or a blank map where you can add other aviation layers like airspace, airways, etc. My preference was to overlay the radar on an en-route IFR chart. Areas where radar data has not been received (or are outdated) are slightly opaque, giving you a very clear picture of what radar data you have (or are missing).

Local NEXRAD granularity - WingX

En-route NEXRAD - WingX

 A few interesting observations about radar using this setup:

• High resolution "local" NEXRAD images are downloaded for approximately 200-250nm of your present position. The FAA says 250nm in the AIM. In practice I noticed a few opaque 'strips' toward the outer reaches. Based on this I'd say 200nm is a good safe range. This seems fine for the type of flying I do but folks flying faster (i..e turbine) aircraft may have a different impression. Then again, they are more likely to have on-board weather radar 

Local NEXRAD coverage on a clear day - WingX

• How old is that image, anyway? The WingX support folks who told me old data 'strips' were made opaque after 10 minutes. SkyRadar has the data's age printed right there on the screen -- but its not clear what that age means considering you could be looking at many strips of radar data at a time (i.e. if you zoom out a bit)

NEXRAD "strips" that were too old or not received. This usually corrected itself within a couple of minutes. Occurs in either app - WingX

• The AIM says the local NEXRAD data is broadcast on a 2.5-minute interval, with new data arriving into the FIS-B system every 5 minutes. By my math, an image you're looking at as valid on the screen could be 25 minutes old, worst-case (NEXRAD itself takes 5-10 minutes to produce an image). Needless to say, this is not a tool you'd want to use to tactically avoid convective weather or to try to make a run through a 'hole'

• A low resolution NEXRAD composite for the continental U.S. is transmitted on a slower interval (10 minutes). The SkyRadar iPad app displays it, but WingX doesn't just yet (12-March-2012: A new WingX update arrived which supports the long-range NEXRAD composite. I'll try it out next time I take my airplane up).

Low-res nationwide NEXRAD composite. Useful when you're zoomed way out - SkyRadar.

METARs & TAFs are downloaded within either a 100 or 500nm range, per the AIM. In practice I have seen METARs & TAFs consistently available for out to about 500nm away away from my position on every flight.

A nice thing about WingX is how it manages this data. You tap next to an airport (any airport), hit weather, and the METARs/TAFs/PIREPs (etc) are displayed with the closest to the station first and radiating out from there. This is simple and intuitive, and means rapidly getting at the information you want (how's the weather surrounding some point in space) without a lot of head-down time in the cockpit. I like that.

TAFs - WingX

METARs - WingX

With the SkyRadar app, you've got to scroll over each airport of interest to display its METAR and TAF (if they exist at that airport).


PIREPs are downloaded within a 500nm radius. I did a couple of tests to see how efficient the system is at disseminating a pilot report. Flying over the California/Arizona border going east, I gave a pilot report verbally to flight watch. It was mostly benign weather, so I reported a smooth ride and the calculated wind aloft. It never showed up on the ADS-B feed. When I looked for it online after landing, it wasn't found either - I can only assume the flight service guy never sent it in.

My PIREP - WingX

On the return trip a couple days later, I encountered some mountain wave in western New Mexico and gave a pilot report. My PIREP showed up on the ADS-B feed to the iPad about 5 minutes later. Very cool. Similarly, on a recent trip to southern California where I diverted for weather, the receiver picked up pilot reports of icing that were brand new, not present when I checked weather on the ground prior to takeoff not an hour before. That helped my decision making as the minimum IFR altitude in the area was right about where the icing PIREPs were.

Similar to METARs & TAFs above, the pilot reports in WingX are shown in order of distance radiating out from a particular station you're interested in. This is an area where the SkyRadar app is lacking; per their documentation you have to go hunting around for an icon next to an airport or VOR nearby to where a pilot made their report (this is per SkyRadar's literature; I never did see any in flight).

NOTAM (D & FDC), and TFRs are sent out with 100nm. That seems arbitrarily close, particularly for TFRs. Displaying NOTAMs is similar to METARs & TAFs above - scroll over an airport of interest with the SkyRadar app, or be given all of them radiating out from some airport using WingX.

Potential gotchas? WingX does not appear to currently support displaying TFR data, and it doesn't explicitly say if it supports FDC NOTAMs. This area is decidedly one where the SkyRadar app does better, pending further software development.

America's most bogus (Disneyland) TFR - SkyRadar

NOTAM-Ds - WingX

NOTAM "D" & "FDC" for Santa Maria - SkyRadar

AIRMETs are sent out within 500nm.WingX provides the AIRMET text in a similar, geographically oriented format when looking at weather for a particular airport. Surprisingly, I couldn't find any AIRMET data in the SkyRadar app, on a flight when there likely would have been one in the area for low ceilings/IFR.

AIRMETs - WingX

SIGMETs are transmitted within a 500nm radius as well, but neither SkyRadar nor WingX appear to support dissemination of these yet.

Winds & Temperatures aloft are sent within a 1000nm radius (so half of the lower 48, roughly). SkyRadar shows these nicely - just pan around an area and you'll see a table of forecast wind & temperature aloft data from the nearest forecast point. WingX does not currently support winds & temperatures aloft from the ADS-B receiver. It will show you winds from the last time you downloaded weather from the internet.

Winds & Temperature aloft data is shown from the last internet weather download - WingX

Special Use Airspace status is sent out within 500nm. This is another product that the SkyRadar app supports, but WingX does not. I had to hunt around to find a hot restricted area using the SkyRadar app. Frankly, its one area of the ADS-B feed I don't think I'll rely on regardless of software support. I want to hear ATC tell me that a particular restricted area is cold before entering. Whether VFR a pilot elects to fly through a hot MOA is a whole discussion and judgement call in itself, but again my preference is to ask ATC.

Special use airspace status - SkyRadar