Datalink or Sferics?

A friend of ours, a California resident, laments that the only thing he misses in living on the West Coast are thunderstorms. While we understand the sentiment, being based in Florida-the world capitol of lightning-we certainly dont share the longing.

But we can say that thunderstorms have become infinitely more interesting in the past couple of years for one reason: datalink weather for the cockpit. Summer flying in Florida used to hold a certain angst if not an outright terror but being able to see thunderstorms develop, move and die on a 256-color cockpit display makes them more fascinating than frightening.


Datalink is well established enough now to be nearly standard equipment in some classes of GA airplanes, yet owners who havent used it still ask us which is better, datalinked NEXRAD weather or sferics devices such as Stormscopes and Strike Finders?

The answer is easy and unequivocal: datalinked NEXRAD is hands down superior for weather avoidance to any sferics gadget. Period. If budget allows, having both would be nice-and some owners say necessary-but if youve got the budget for only one system, it should be datalink weather. What follows is our analysis of why we think this is so.

When Paul Ryans first Stormscope debuted in the mid-1970s, it was a marvel, albeit a pricey one. It worked better than anything else because for light singles, there really wasnt anything else.

Stormscopes have improved immensely over the years, but they have remained expensive, due to the niche nature of the market and the lack of significant competition. When the Strike Finder appeared in 1992, it ignited a patent lawsuit against Insight by BF Goodrich-which then owned the Stormscope line-and some price competition, too. But still, for other than hardcore owners flying a lot of convective weather, Stormscopes still represented a substantial investment many chose not to make.

The advent of affordable datalink has depressed sferics prices somewhat, with both Stormscopes and Strike Finder installed prices softening somewhat. Further, more sferics gear is appearing on the used market, but when you add all this up, compared to datalink, new Stormscopes and Strike Finders arent much of a bargain, in our view.

A state-of-the-art WX-950 retails for $8730 for a typical installed price of $7000 to $8000, allowing for the usual shop discounts. Older technology WX-1000s, with CRT displays, install for about $10,000 and gyro-stabilized WX-1000Es with course overlay cost about $14,000 to install. For those who have an MFD or Garmin GNS430/530 for display, the WX-500 remote Stormscope is installing for $7000, give or take. But it no longer overlays strike data on the map, but uses a dedicated strike page.

Our survey revealed mixed opinions on the Strike Finder versus the Stormscope models but Insight Avionics has recently lowered Strike Finder prices to $4495 for its basic model, meaning it can be installed for under $6000 in many airplanes. The best deal in years, but still not cheap.

The best values in Stormscopes are found on the used market. Given the state of storm avoidance technology, the age of some of these units and the availability of relatively cheap datalink, we think a bargain price on a museum piece Stormscope is no bargain at all.

We wouldnt consider anything older than a WX-11 worthy of hacking up a panel to install and we would prefer nothing earlier than a WX-1000. Neither of these, by the way, are inexpensive to install and all of the Stormscope models have high flat-fee repair costs, should any be needed. The specialized cables these devices require are also expensive.

You can find yellow-tagged WX-1000s of unknown provenance for about $6000 used. Plan on another $1200 to $2000 for installation and parts.

A proper installation will require careful skin mapping and the fact that there are hundreds of Stormscopes out there doing a superb job of painting wingtip strobes and noisy alternators suggests that many shops either dont know how to skin map or just arent bothering. (The WX-900 in Aviation Consumers Mooney fits the profile; its an incorrigible strobe detector.) Also on the used market, were beginning to see some WX-500s appear, the $4500 range.

Contrast that with datalink prices. At the bottom end, the best deals are on new, not used equipment. Not that theres much used gear out there. Unless your hobby is self-flagellation, youd want to avoid Garmins GDL49 and WSIs AV200, both poster children for the it-seemed-like-a-good-idea-at-the-time school of avionics marketing and engineering.

On the other hand, while the GDL49 was a dud, the portable GSPmap396 was a smash hit and, improbably, after barely a year on the market, its turning up used as owners trade up to the new GPSmap 496. (See Aviation Consumer, September 2006 for a review.) At about $1800 to $2000 used, the GPSmap 396 represents the least expensive, seamless way to get into datalink. Seamless means no load-it-yourself software and little hassle with wires and externals.

For those who dont mind that sort of thing, the PDA route is always an affordable option and remains the absolute cheapest way into datalink. Control Vision sells complete PDA-based setups that include XM-based weather for prices between $1500 to as much as $4500 for complete tablet/EFB products. These systems are functional, easy to use and offer upgrade possibilities that Garmins dedicated portables dont.

Further, even at the high end, PDAs and tablets are both cheaper and more multi-talented than sferics gear. On the other hand, owners have complained to us that PDAs can be a nuisance to set up and secure and are occasionally plagued by bugs in the hardware and software. They arent as mechanically robust as dedicated portables and weve heard about customer service issues with vendors.

As everyone predicted it would, the panel-mount datalink market continues to shake out, although the end may now be in sight. Garmins $5000 XM Radio-based GDL69 appears to be the strongest contender and is capable of displaying all of WxWorxs menu of services on Garmin GNS430/540 navigators, plus the MX20 and GMX200 MFDs. Although the GDL69 is somewhat late to the market, Garmin is making up for that in sales catchup.

With its ORBCOMM-based narrowcast datalink concept, Avidyne made the same technological toe stub that Garmin did with the GDL49. We heard from quite a few buyers unhappy with its performance. Avidyne addressed this by integrating the two systems-ORB-COMM and XM Radio-into a concept it calls MultiLink. In the Continental U.S., the XM receiver delivers realtime datalinked weather using Avidynes proprietary weather products, not WxWorx.

Outside of XMs U.S. coverage, the ORBCOMM component delivers Avidynes weather products. How-ever, this system displays only on Avidynes EX500/5000 MFDs, not panel-mount navigators or other MFDs. The MultiLink-capable EX500 retails for $8995, the larger EX5000 for $13,995. Prices are higher for Avidyne MFDs that are also capable of displaying ships radar.

Bendix/King can said to be the first provider of reliable NEXRAD data to the cockpit, with its groundbased Wingman service using the $5920 KDR510 datalink receiver. This system plays on Bendix/Kings own KMD series of MFDs, including the KMD250, 550 and 850. Owners report that its robust and reliable but has one glaring weakness: limited coverage. It usually doesnt work well if at all on the ground and owners complain that they cant get a look at nearby weather until climbing above 4000 to 6000 feet.

Recognizing this, Bendix/King will phase out the groundbased network in about 18 months and at Oshkosh, it announced the new KDR610, which will use XM Radio and the WxWorx datalink products. The KDR610 is scheduled for the first quarter of 2007 but we dont have prices for it yet.

Meanwhile, WSI is busily attempting to repair its own datalink disaster by switching its datalink business from a commercial satellite provider to Sirius Satellite Radio, after it encountered what it said were unresolvable technical issues with the previous provider.

This will, unfortunately, render owners of WSIs original AV100 and AV200 datalink receivers high and dry, since those boxes wont work with Sirius radio. Earlier this year, WSI offered to support its datalink customers by offering Sirius-based replacements for the AV100 and AV200. These are expected to be available by the end of the year and WSI is offering a trade-in deal that will leave owners largely whole on the exchange.

The point of buying this variously expensive equipment is to avoid storms safely if not always comfortably. Datalink brings the additional advantage of other weather products, such as METARs, TAFs, winds aloft and satellite imagery.

When we surveyed owners using both sferics and datalink, we learned that the term storm avoidance is not a one-size-fits-all concept. Some owners are perfectly happy using datalinked NEXRAD imagery to steer widely around storms and dont care a bit about flying 50 extra miles to do it.

A smaller number of pilots are more sporting and will use NEXRAD, sferics and-if they have it-onboard radar to pick through cells and squall lines. These are the owners who are more likely to see the Stormscope versus datalink debate not as either/or, but a why-not-both question.

In our view, this philosophical divide illuminates the buying decision. If your avoidance strategies tend toward the conservative, datalink should be more than adequate for your purposes. But if you fly frequently in energetic convective conditions and have the skill (and nerve) to thread the needle through intense cells, sferics will provide sometimes critical information.

Although its relatively new, datalinked weather has been around long enough and is being used widely enough to have revealed definite strengths and weaknesses. At least one of these-NEXRAD latency-appears to be a more theoretical than a practical problem, according to our survey of users. Many owners seem to have a more polarized view of the limitations of sferics gear, either loving or hating it. Several owners told us they no longer use their Stormscopes since having installed datalink.

DATALINK PROS: Nothing comes close to providing the equivalent big picture view of relevant weather than datalinked NEXRAD.

Most of the systems are capable of looking at weather several hundred miles distant, something that neither onboard weather radar nor sferics devices can do as effectively or in real time.

Datalink delivers weather information thats not limited to thunderstorm avoidance, while sferics and onboard systems are one-trick ponies.

With its six VIP levels, NEXRADs weather depiction is unambiguous and easy to interpret.

DATALINK CONS: Latency, the delays of NEXRAD imagery from real time by at least five minutes and sometimes more, continues to be a worry. Users we surveyed downplayed this disadvantage.

Although WxWorx service displays lightning strikes, resolution is too poor to be useful.

Latency notwithstanding, NEXRAD tends to overestimate the threat, according to users, painting higher VIP levels than appear to exist.

XM Radio and Sirius Radio are still too new to have established take-it-to-the-bank long-term survival.

Monthly fees of $30 or $50 add up, especially for occasional users who may pay $600 a year for something they need only three or four times a year.

SFERIC PROS: Latest technology is mature and effectively plots lightning strikes. If there are no detected strikes, theres lower probability of significant turbulence.

Used in conjunction with airborne radar or NEXRAD, sferics gives valuable real-time information on cell intensity and build-up directionality.

In embedded conditions, sferics is a high-confidence indicator of whether rain is benign or threatening.

No monthly fees.

Relatively reliable when properly installed.

SFERICS CONS: Range and azimuth of strike data can be iffy, especially for older models which dont reject radial spread effectively.

Absence of strikes is not always an indicator of absence of turbulence.

Effective skin mapping is a must if the sferics are to work reliably. Owners complain that many dont.

Compared to the lower end of datalink-portables-sferics require installation and are thus expensive.Sferics consumes panel space to do one task that may rarely be needed

Depending on the model and conditions being flown, sferics devices require interpretation. Being wrong can range from unpleasant to fatal.

In our view-based on our own experience with sferics and datalink used together and separately and based on what owners we have surveyed have told us-there are situations in which having both sferics and datalink make sense. In a new airplane with a PFD or MFD-steam gauges or not-the cost of adding a WX-500 remote Stormscope is a nickel buy thats well worth the trivial cost.

And speaking of cost, if youre one of that small band of hardy owners to whom a $6000 to $8000 avionics upgrade is chump change and you fly enough threatening weather to justify it, we think sferics is still a player in the modern cockpit, but only if used alongside datalink. Datalink is simply too much of a game changer to ignore, in our estimation.

Although a couple of pilots we surveyed told us that if they could buy only one system, it would be a Stormscope or Strike Finder, the vast majority of owners using both recommended datalink over sferics if a single system is contemplated.

We agree with that assessment. Despite its shortcomings and even considering recurrent monthly charges, datalinked weather is cheaper, more flexible, easier to interpret and has more headroom to grow than do sferics devices.

We thus cant make an argument for installing a new Stormscope or Strike Finder in an airplane that doesnt already have datalink weather of some kind. While its true that datalinks long-term future is not absolutely assured, its also true that dollar for dollar, its simply a more capable system than sferics.

What about removing sferics in favor of a datalink receiver? This is strictly a question of panel space and budget. In our airplane, for instance, the WX-900-a marginal performer-is taking up space we need for an electric backup gyro. Its not worth several thousand dollars to rearrange the panel just to retain the Stormscope, so well probably remove it in the not-too-distant future.

Paul Bertorelli is Aviation Consumer’s Editor at Large. In addition to his valued contributions to Aviation Consumer, his in-depth video productions on sister publication AVweb cover a wide variety of topics that greatly contribute to safety, operation and aircraft ownership. When Paul isn’t writing or filming, he’s out flying his J3 Cub.