Future Flight: Beaming Up the Weather

Part 3 of 12

Of all the future technologies that await general aviation, the uplinking of textual and graphical weather could provide the greatest safety benefits. Think of it: Near-real-time Doppler radar imagery, contouring in six intensity levels, free of the attenuation effects that dangerously distort airborne weather radar returns. The projected locations of any storm cells for the next hour. Fast plotting of lightning-strike locations from the nation's ground-based lightning-detection network without the misleading, radial-spread signatures that characterize today's on-board lightning-detection instruments. The latest METARs and TAFs, called up on your display screen anytime you desire. Weather depiction charts. Satellite views. Graphically depicted airmets and sigmets, popping up on your navigation display as they are posted. Same thing with areas of forecast or reported icing and turbulence. Other late-breaking news from flight service stations and air traffic control, such as restricted areas that just went hot, can also be uplinked and plotted on your display. And more — such as e-mail and telephone service.

To make all of these cockpit wonders a reality, three elements must be in place: weather information providers, methods for uplinking data, and certified cockpit displays. Some of these elements are already up and running.

Weather service providers

Weather providers, for example, have been in business for years. The big players in this field include firms such as DTN/Kavouras, Litton/WSI, Universal Weather, Harris Corporation, Unisys, and, of course, the National Weather Service's aviation weather products, gathered and produced by the NWS's Aviation Weather Center. The text and graphics products put out by these outfits are accessible through the Internet and provide a wide array of products — for a fee. Except for the government's DUATS and NWS-generated weather products, that is. To get an idea of what the latest government products look like, check out the Aviation Digital Data Service (ADDS) Web site ( http://adds.awc-kc.noaa.gov/projects/adds/index.html).

The number and quality of the weather products are changing at a very rapid pace. One recently introduced product shows the areas and vertical extents of any areas of suspected icing conditions, and identifies whether or not the icing ought to be of the very hazardous, large-droplet type.

Different suppliers have come to take on various personality types. DTN/Kavouras seems to be perceived as the megasource of the electronically represented weather world. Litton/WSI's aura is interpreted by some as most heavily influenced by meteorologists. Universal is known as having a big-iron, kerosene-burning personality. The NWS/ADDS's products, being free, are undoubtedly the best value for the money.

Regardless of these current products and perceptions, it's a safe bet that all will undergo significant change as the various companies and organizations respond to pilot feedback and market pressures. Expect more and better features in the future, though the ones that are available now are sufficiently impressive.

Datalink issues

As good as the weather graphics might be, they're of no use unless the signals carrying them can make the trip to the cockpit. This is where datalinking enters the picture.

Last month, we discussed datalinking primarily in terms of the uplinking and downlinking of air traffic information (see "Future Flight: Links to Tomorrow," February Pilot). Some of the same issues confront the weather delivery systems of the future. In particular, the problems of bandwidth and coverage are major factors — and hurdles to overcome — in the leap to future in-cockpit weather technology. That's because weather graphics make for huge file sizes, and strategies for getting them to the cockpit are still evolving.

The bandwidth of a given frequency can be conceptualized using a conduit or water-pipe analogy. The bigger the diameter of the pipe (bandwidth), the more water (weather and other data, such as traffic information) you can move. Narrow the pipe, and the flow of water is restricted. Similarly, if you try to force too much data over too narrow a bandwidth, some of the transmitted information won't make it to or from the cockpit. Instead, pilots might receive incomplete information, or no datasets at all. In the case of traffic information, some critical targets may not show up on cockpit displays. In the case of weather graphics — which can take up a lot of bits and bytes — a file simply may not be able to squeeze through a too-narrow pipe...er, bandwidth.

Bandwidth is sometimes expressed as a function of how fast data transmissions take place — sort of the way we speak of modem speeds. Today, the available datalink bandwidths range from 2,400 baud per second (bps) to 31.5 kbps.

Generally speaking, the lower the frequency the less data you can move; the advantages, however, include longer-range transmissions. The higher the frequency, the more data you can transmit, but range is somewhat less — and the power required to make those transmissions goes up. Of course, it all depends on what you define as "data." Text messages, such as METARs or TAFs, take up little bandwidth and move easily. But a Nexrad image of the Northwest United States? That's another matter.

Airplanes also have to be in a position to receive uplinked weather, too. They have to be in the line of sight of ground-based antennas and within the coverage areas of any satellites being used for weather — or any other — uplinks.

Satellite or terrestrially based?

When it comes to coverage, satellites win big over ground antennas. From their perches in orbit, satellite signals can cover entire continents and reach airplanes at any altitude — even on the ground, and even though they may use higher-frequency transmissions. Ground antennas operate on a line-of-sight basis, so their signals radiate upward in a cone-shaped pattern. The problem here is that airplanes at too low an altitude, or flying around high terrain, may not be able to receive signals from a ground antenna, in much the same fashion as they might not receive a VOR signal.

To correct that problem, service providers using ground antennas have to install plenty of them in order for coverage levels to be acceptable. And indeed, all of these providers are now in the process of building up their antenna networks and expanding their coverage areas.

Today's delivery systems

Currently, there are several datalink providers who provide weather information uplinks. Some operate on a broadcast basis, meaning that information is broadcast on a certain schedule, and pilots simply receive information — based on their position. Request/reply service is self explanatory: You ask for certain information, and the system sends it back to your cockpit display. In the future, various levels of service may be offered: a free, text-based service from the FAA as a basic service; and increasingly diverse sets of information offered with higher, fee-bearing tiers of service. Think of it as cable TV today — you have a basic service level, and then you have the extra service packages that charge you for one or more premium channels such as HBO or Showtime.

EchoFlight uses the Orbcomm network of Orbital Sciences satellites to send weather, provide position reports, and send and receive e-mail. There is worldwide coverage — except for the polar areas — at all altitudes. Bandwidth is 4,800 bps, and transmissions are made using bursts of compressed data. This is a request/reply service that lets you ask for weather images anywhere in the United States. EchoFlight currently uses its StratoCheetah system as a display, which is essentially a laptop computer or other portable display that you plug into the cockpit. However, a recent agreement with Garmin will let users put EchoFlight's imagery on a Garmin 430 or 530 panel-mounted color display. The service costs $25 per month, and each image can cost you between 50 cents and $1 per view. Call 888/948-9657 for further information, or see the Web sites ( www.echoflight.com and www.orbcomm.com).

Arnav currently uses a ground-based VHF broadcast system for its WxLink services. It won a five-year FAA contract to provide flight information service (FIS) to pilots. Under this scheme, basic text information is free. Extra services such as weather graphics are provided for a fee. Coverage in the United States is growing rapidly, and national coverage above 10,000 feet should be available by the end of 2000. Bandwidth is 2,400 or 9,600 bps, and unlimited service costs $595 per year. For the latest information, call 253/848-6060 or check out www.sagemavionics.com.

NavRadio is another ground-based VHF broadcast system. It now has regional coverage but plans to offer national coverage above 5,000 feet by 2002. Bandwidth is 31.5 kbps, and a subscription costs $400 per year. Honeywell recently purchased NavRadio, so click on www.navradio.com for the latest information on prices and services.

ARINC, a well-established company with strong airline ties, is another ground-based VHF provider. Worldwide coverage above 10,000 feet is available today. Bandwidth is 2,400 bps, but an upgrade to 31.5 kbps is planned for 2002. This is a request/reply service that costs $100 per month. Call 410/266-4000 for more information, or check out www.arinc.com.

AirCell, the provider of airborne telephone services, provides both voice and data services. Now, coverages are regional in scope, but the company says that national coverage above 5,000 feet will be available by mid-2000. This is a request/reply service that now operates at 9,600 bps and costs $25 per month and $1.75 per minute of access. Call 303/379-0200, or click on www.aircell.com for more information.

Iridium, like EchoFlight, uses low-earth-orbit satellites to provide phone and data service — both for aviation and the nonflying public. Coverage is worldwide, service is request/reply, and bandwidth is 2,400 bps. Service now costs $50 per month and $1.75 per minute. Iridium's recent financial difficulties may have upset its plans for the future, but call 888/474-3486, or click on www.iridium.com for the latest.

Displays

The number, size, quality, and features of the displays offered today are bound to go up — and fast. Call them flight situation displays, multifunction displays, or control display units, but the current crop gives a tantalizing look at what's to come, and in vivid color. Most can combine navigation (such as moving maps, including VFR and IFR charting), traffic, and terrain display information — not just weather. Many will be able to accept either satellite- or terrestrially based datalinks. Here are today's players in the large-display game. The prices mentioned are subject to change, and may not include the cost of antennas, installation fees, and certainly do not include the costs levied by the service providers.

The UPS Aviation Technologies Apollo MX20 is a $5,995 unit that is currently available and has already been used in ADS-B trials depicting uplinked traffic information.

The Archangel CDS is a $9,995 display that, like the rest listed here, can show lightning-detection returns, IFR en route charts, and TCAD information.

The Arnav MFD 5200 ($7,995) and ICDS 2000 ($12,995 — the ICDS stands for integrated cockpit display system) have top-of-the-line features like terrain warnings, IFR approach displays, BFGoodrich Skywatch, TCAD, and TCAS. All this, and uplinked weather, too. The 5200 is certified and now offered in the Cirrus SR20.

The $9,995 Avidyne FSD FlightMax 440 is another full-featured, certified situational display that can even make your existing monochrome radar yield color imagery. A growth version, the FlightMax 740, should even be able to show engine information and provide engine-trend monitoring.

The Honeywell Bendix/King KMD 150, 550, and 850 ($3,995, $4,795, and $6,250, respectively) also offer a full set of display features. The 150's price reflects its lack of an integral GPS receiver — but you probably already have one of those.

Changes and improvements to weather products and datalink technology seem to take place at breakneck speed. It's a safe bet that in a matter of weeks more services, different fees — and even new providers — may pop up on the scene. Soon, for example, you might be able to enter a flight plan and request weather products for your route of flight on your home computer over the Internet, then have it uplinked to your airplane's large-screen multifunction display, where it waits to appear after you turn on your master switch.

Links to additional information about weather and datalink technology can be found on AOPA Online ( www.aopa.org/pilot/links/links0003.shtml ). E-mail the author at [email protected] .