Cockpit Datalink Weather

 - February 27, 2009, 8:45 AM

Pilots who have grown accustomed to flying with up-to-the- minute weather graphics and information broadcast to the cockpit through the XM or Sirius satellite radio services are probably aware that the companies successfully completed their “merger of equals” last year. The deal created a combined entity called Sirius XM Radio Inc. that still operates very much as two separate services, including providing weather data through WxWorx over the XM satellites and WSI InFlight using excess capacity on Sirius’s network. Many may also have been following subsequent stories about the fierce tug of war over the company’s future as the U.S.’s two biggest satellite television services, Dish Network and DirecTV, battled for control of Sirius XM. How the story plays out could have a bearing on whether Sirius XM survives and determine if the weather data services will stay on the air.  For now, it appears pilots can breathe easy.

Liberty Media, the company that owns DirecTV, has agreed to lend $530 million to Sirius XM in exchange for a 40-percent equity stake, saving the satellite radio provider from possible bankruptcy and blocking a takeover by Dish Network. Charles Ergen, CEO of EchoStar, the company that operates Dish Network, had been buying up Sirius XM debt in recent months with the goal of taking control of the company.
Sirius XM chief executive Mel Karmazin, in an attempt to prevent that, had asked for debt help from DirecTV head John Malone, and had also threatened bankruptcy to keep Ergen from wresting away control of the satellite radio company. Investors who would have been wiped out by a bankruptcy filing threatened a lawsuit to oust Karmazin if he tried to take that route. At press time, it appeared that Sirius XM is safe for now thanks to DirecTV’s debt aid. 

But even if Chapter 11 protection or a takeover eventually happens, the firms that supply weather data to the cockpit insist their services will remain up and running through the turmoil. “There’s no question that XM will be a viable delivery method for our weather data for a long time to come,” said Robert Baron, president and founder of Baron Services, the company behind the popular WxWorx offering. “The response in the aviation community to XM weather has been phenomenal. Tens of thousands of pilots are using it. It’s important to us, and it is important business to Sirius XM.”

The satellite radio provider is currently drowning in about $3.5 billion worth of debt, meaning its long-term viability is by no means assured. The company currently has some 20 million subscribers paying about $10 a month for its radio services, so there is a strong impetus to see Sirius XM survive in some form. Several more large debt payments will come due in the coming months, making the deal with Liberty Media crucial for Sirius XM. Weather data delivery probably isn’t even on the radar screens of the key players involved in deciding Sirius XM’s fate. Still, pilots who are contemplating whether to invest in the technology have a tough decision ahead.
Sirius or XM?

The good news is that the satellite radio providers are facing the same fate, so the decision about which service to choose can be made based entirely on the merits of the competing offerings. The WxWorx/XM service is the more popular of the two, but the WSI brand is better known among pilots, especially those familiar with the PC-based PilotBrief Pro service used at many flight departments and FBOs. Each of the airborne services offers a similar menu of weather products, including Nexrad radar graphics, Metars, TAFs, TFRs, sigmets and airmets, winds and temperatures aloft and other data depending on the service level. Pricing for each starts at $29.99 per month for basic services and goes up to $49.99 for the mid-level services and, finally, $99.99 for the WxWorx Aviator Pro package or $70.75 for WSI’s Premium service.

WxWorx on Wings, the name of the airborne weather service that the XM satellites transmit to the cockpit, is available using a variety of electronic flight book (EFB) portable displays and handheld navigators as well as integrated avionics systems such as Rockwell Collins Pro Line 21, Avidyne Entegra, Garmin G1000 and Honeywell Primus Epic. Heads Up Technologies of Carrollton, Texas, supplies the XM weather receiver, which links through a Comant antenna to provide graphical and text weather updates across the continental U.S., Canada and parts of the Caribbean.

Introduced in 2003, the WxWorx service became an immediate hit with pilots, who suddenly went from relying on spartan request-reply data broadcast over aging satellite networks like Orbcomm, to the always-on XM service and its veritable fire hose of information for an “all-you-can-drink” price. The change was nothing short of revolutionary, on par with other major advancements in aviation safety like TCAS, TAWS and GPS positioning. Now that pilots have it, it’s not surprising that they’re worried about having to fly without it.

Not long after WxWorx and XM joined forces, WSI struck a deal with Sirius for the broadcast of its weather data, which at the time was being transmitted using MSV satellites. WSI last year finally completed the migration of InFlight customers who had been using the MSV-compatible hardware to the new AV-300 and AV-350 satellite receivers that work with Sirius. A company spokesman said more than 80 percent of the WSI InFlight customer base made the switch, which was a much higher number than had been expected. Since the changeover, WSI has added around the same number of customers it initially lost in the switch, putting WSI back where it was, in terms of the number of total InFlight subscribers.

Bolstering InFlight’s subscriber retention was Garmin’s release of software that allows the WSI InFlight graphics to be shown on the GMX200 multifunction display, which replaced the WSI-compatible MX20. Another plus was Avidyne’s recent release of software for its MFDs that supports Canadian weather and Metars and TAFs from Canada down into the Caribbean and Central America. 

In the meantime, WSI released InFlight Version 4.2 display client software that allows the services’ weather graphics to appear on EFBs while improving the look and feel of the interface and adding some standard Windows functionality, the spokesman said. This new software also lets all InFlight subscribers access newer features such as cloud tops, surface analysis maps, enhanced lightning and current icing severity. Around 10 percent of the InFlight subscriber base has upgraded to the new software, the spokesman added.

WSI has been able to improve its lightning detection product through a partnership with Toa Systems. The companies have created the U.S. Precision Lightning Network, which claims to have two to three times the detection capability of competing networks. The network not only detects cloud-to-ground lightning but also displays cloud-to-cloud strikes for a more complete lightning picture, the spokesman said. By leveraging the detection technology and combining it with the latest Version 4.2 display client software, WSI claims it can depict lightning to one 100th of a degree of latitude and longitude.

WSI also provides the weather information for Avidyne’s MLX770 receiver, capable of providing weather globally through the Iridium satellite network. For now, radar data available through the service is limited to Western Europe, but coverage of additional regions including Australia and South America is planned, and Metars and TAFs are available worldwide. Last month, the European Aviation Safety Agency approved installation of the MLX770 transceiver in pressurized aircraft, after granting an earlier approval for non-pressurized aircraft.

The MLX770 is initially designed to interface with Avidyne’s EX500 and Entegra systems. Avidyne is also working with third-party display and EFB manufacturers to develop interface compatibility for future installations in Part 25 business jets. WSI and Avidyne are working to expand the Version 4.2 software into a dual-mode product that would let operators of long-range business jets use the WSI/Sirius service in the U.S., Canada and the Caribbean and then switch to the Iridium-based service elsewhere.

The list price for the MLX770 is $11,995, including the antenna. Service pricing is expected to be in the $70- to $120-per-month range based on 10 hours of flying per month. Unlike the always-on XM- and Sirius-based services, MLX770 users must pay for access by the minute.

Comparing WxWorx and WSI InFlight
When taking a closer look at what’s offered with the WxWorx on Wings and WSI InFlight services, one finds that the features are fairly similar. WSI offers lightning in its Basic package while WxWorx holds that information back until subscribers purchase the mid-Aviator level. But WxWorx substitutes city forecasts in its lower-tier Aviator LT package and offers a longer menu of features with its Aviator and Aviator Pro plans, such as Pireps (available at the Aviator level) and visibility, convective outlooks and hurricane tracks (Aviator Pro).  

A notable difference between the two services–and the one that subscribers probably wonder about most–is WSI’s use of so-called NOWrad radar versus WxWorx’ Nexrad composite mosaic view. Here’s a breakdown of how the techniques differ: WSI uses only base reflectivity (that is, the first tilt angle of the radar) while WxWorx uses a vertical composite that combines a number of different tilt angle sweeps and puts them into a single picture. There are pluses and minuses to each technique. But first it’s important to understand that a Nexrad radar makes many “cuts” of the atmosphere at different tilt angles (up to 16), while constantly relaying updated information back to the weather service providers. This is the reason it takes about five minutes for a radar site to perform a complete sweep of the atmosphere.

The primary range of each Nexrad site is 125 nm. Using a single image from the radar’s base reflectivity sweep, as WSI does, provides a “snapshot” of the atmosphere that provides a good view of precipitation and also of storm gradient, or the area where precipitation changes from light to heavy. If the physical distance in an area of storm gradient is short, pilots can expect strong shear. WSI’s mosaic also takes the normal range of each Nexrad radar site and adds to it the extended range. This expands the effective range of each site from 125 nm to more than 215 nm. The technique is claimed to provide a more complete radar mosaic in the mountainous western region (although still not perfect) and offshore.

The WxWorx philosophy is a bit different. Every five minutes its network goes out and grabs the current sweep of each of the nation’s 171 Nexrad radars at several different heights, including the data for five minutes of prior sweeps. Computer algorithms create a composite image of all sweeps at each point, looking at the highest reflectivity for a given location. This provides a little bit too much information, however, giving the XM/ WxWorx display a tendency to show the weather as being more imposing than it really is.

Detractors say this composite view of the weather can look “smeared” because it combines many different sweeps. Pilots can think of it a bit like taking a time-exposure photograph and leaving the shutter open for five minutes. WxWorx admits the WSI view is sharper, but says it prefers the composite mosaic because it provides more cuts of the atmosphere and, consequently, more information. “We’re okay with showing too much information to pilots,” said WxWorx’ Baron, a private pilot with multi-engine and instrument ratings. “In fact, I prefer it that way.”

With both services, a picture from all Nexrad sites is blended together into a national mosaic of the entire U.S. Some parts of this mosaic will be five minutes old, and some more recent. It takes 15 to 20 seconds for the weather data to travel from the radar site to the satellite and back down to the cockpit. This means that within 30 seconds the pilot has on his cockpit display some information that is less than a minute old and some that is as old as five or six minutes. This fresh information then decays in the cockpit for another five minutes, meaning data that the pilot sees on the display can actually be 10 or 11 minutes old.

Connecting with FlightDeck Connect
WxWorx and WSI are in the spotlight for good reason when discussing weather datalink options, but they are still relative newcomers compared with Universal Weather & Aviation, which has served as business aviation’s global airborne weather link for years. The company’s FlightDeck Connect service offers aircraft equipped with datalink receivers and satcom or VHF transceivers, a wide range of graphical weather information, including Nexrad images over the continental U.S., and worldwide turbulence, icing, graphical Metars and winds aloft.

The service also allows users to send and receive text messages in the cockpit using the FMS CDU.

FlightDeck Connect is compatible with a range of avionics from a variety of manufacturers, including the Honeywell CMU Mark II, Acars MU; Universal Avionics UniLink UNS-series FMS; Teledyne Controls TeleLink (BBJ and Global Express); Rockwell Collins Pro Line 21 with the CMU 4000, DLM 900 and CMU 900; and other open-architecture Acars units.

The service displays high-resolution color weather graphics showing IR Satellite, significant weather, icing, turbulence, winds and temperatures aloft, IFR/MVFR, U.S. Nexrad composite radar and radar tops and movement. Text weather includes terminal weather reports, winds aloft, sigmets and pireps. FlightDeck Connect also includes a flight plan recall function (uplinked in the required format to the FMS), free text messaging from the aircraft to any fax, e-mail or wireless device with e-mail capability and free text messaging to the aircraft from any computer or wireless device with Internet/e-mail capability.

Additional capabilities of the Universal Weather service include automatic position reporting, automatic message forwarding of aircraft flight messages (including delay reports, diversion reports, ETA reports, position reports, On/Off reports) to any fax and/or e-mail address, pre-departure clearances, automated oceanic clearances, digital ATIS and terminal weather reports.

A Global View with Honeywell GDC
Another option for obtaining weather data after takeoff is tapping into Honeywell’s Global Data Center (GDC), which provides a range of aviation and plain-language weather information products that includes text weather information spanning Metars, TAFs, Pireps, Notams, Sigmets, digital ATIS, terminal weather, winds and temperatures aloft forecasts, area forecasts, route weather briefings, metro and state forecasts and passenger weather briefings.

Graphical weather products include Nexrad radar images, high- and low-level significant weather prognostics, winds and temperatures aloft forecast charts and weather depiction charts, among others. Weather graphics via datalink can be sent and received using an upgraded AFIS data management unit interfaced with either a Honeywell FMZ-2000 series FMS with 6.0 (or higher) software and a CD-820 CDU or with a Global GNS-XLS enhanced FMS and remote processing unit. Available weather graphics products include U.S. national and regional Nexrad maps, U.S. Metar charts, worldwide high-level significant weather prognostics, and worldwide winds and temperatures aloft forecast charts. 

'Cockpit Datalink Weather' PDF