Turbine Pilot

Magellan CNS-10

February 1, 1995

Data link for the masses

Been searching for the on-ramp to aviation's information superhighway? You may be getting close. Aeronautical Radio, Incorporated, better known as ARINC, long-time innovator in aviation communication technology, and Magellan Systems Corporation, maker of GPS navigation units, have collaborated to create the Magellan CNS-10. Weighing in at slightly more than eight pounds and filling 5.75 inches x 4.5 inches of panel space, the device is designed to fit a wide range of aircraft, including helicopters and many single-engine airplanes. CNS stands for communication, navigation, and surveillance, while 10 is the number of channels in the unit's integral GPS receiver.

As its name implies, the CNS-10 combines air-to-ground digital data link communications with sophisticated GPS navigation functions in one compact unit. With an expected base price of $9,995, it promises to give operators of top-end GA aircraft the same kind of big league communications capabilities previously available only to the airlines or Fortune 50 companies — at a small fraction of the cost. And it will do one thing the heavy iron flight departments drool over — automatically report GPS-derived aircraft position.

This last ability, a component of the Automatic Dependent Surveillance (ADS) concept, is an essential part of the brave new world envisioned by some in the Future Air Navigation System (FANS). ADS will allow ATC, or a company dispatch office, to precisely monitor the position of, and communicate with, an aircraft almost anywhere in the world. Since ADS won't depend on radar coverage availability, it will work just as well in the middle of the Pacific as in the middle of Kansas. Routine clearances, aircraft position reports, and other communications grunt work will take place in the background through digital data bursts. Error- prone, time-consuming voice communications will be minimized as bits and bytes flow seamlessly between an aircraft and whatever ground station or satellite offers the best connection at the moment. The hoped-for results? More efficient air traffic management, increased safety margins, and reduced work loads for pilots and controllers.

That's the idea anyway, but the future isn't here yet. By announcing the CNS-10, however, ARINC and Magellan are clearly hoping to hasten its arrival. Recognizing that price tags of $100,000 or higher price tags for traditional airborne data link systems meant limited customer growth potential, the two companies decided instead to approach a totally new market. They've targeted the thousands of air taxi, commuter, corporate, and private operators who they hope will fork over the CNS-10's more palatable $10,000 to $20,000 (depending upon options) price of admission to aviation's Infobahn. With an almost untapped marketplace awaiting them, they just might be on to something.

To understand all the hoopla over digital data link, consider what it has done for ARINC's customers already. Most large air carriers and some corporate flight departments subscribe to ARINC's Aircraft Communications Addressing and Reporting System, or ACARS for short. ACARS is a two-way digital data link system that permits alphanumeric messages to be routed between a particular aircraft and a customer, such as an airline dispatch office. A network of 300 VHF receiving stations guarantees continuous enroute coverage to all flights above 20,000 feet anywhere in the continental United States. The network also provides on- ground and low altitude coverage at more than 275 U.S. airports, including all the major ones. (Other coverage areas include Bermuda, San Juan, Jamaica, Honolulu, Guam, and various sites in Canada, Mexico, and Central America.) Messages between an aircraft and the ground recipient funnel through ARINC's Annapolis, Maryland, headquarters. A separate ACARS function, called Selective Calling or SELCAL, allows subscribers to make voice contact from the ground to participating aircraft within the coverage area.

Airline and corporate subscribers use ACARS to perform a variety of everyday communications tasks that would otherwise clog up VHF voice channels. In airline use, for example, ACARS automatically transmits the off-the-gate and takeoff times of each flight, followed by its touchdown and gate arrival times at the destination. These are routed to an airline's mainframe computer system, making the information available instantaneously to dispatchers. Depending on the installation used in particular aircraft, ACARS can automatically record engine parameters and send them to an operator's maintenance control facility, receive weight- and-balance information from a load controller half a continent away, or send real time winds aloft data to a distant weather office. Crews routinely request weather information, including ATIS reports, which emerge from onboard printers. At many large airports, operators participating in the FAA's Predeparture Clearance program receive instrument clearances through ACARS without ever contacting clearance delivery on voice channels. ARINC processes about 7 million such messages a day from more than 600 subscribers. Use of data link for these kinds of detail-intensive messages saves time and greatly reduces the message error rate compared with voice transmissions. It also frees the crews to concentrate on more important things, like flying.

If 7 million messages a day sounds like a lot, it's a drop in the bucket compared to ARINC's future expectations. The present volume is generated by the 4,000 or so aircraft equipped with ACARS. Add a whole bunch of new CNS-10 users to the stew, along with potential widespread acceptance of ADS, and it's easy to see why the company has high hopes for the future.

Everyone who purchases a CNS-10 will become a user of GLOBALink (yes, another acronym), ARINC's term for its growing communications and customer support infrastructure. According to CNS-10 Program Director Daniel Schwartz, ARINC is still developing a pricing structure for use of the system. He expects costs will range from $100 per month for a single user with relatively simple communications needs to $350 a month for those making frequent use of all services. Schwartz expects the finalized version to be somewhat analogous to cellular telephone pricing plans. (That's somewhat analogous — don't expect a free CNS-10 unit anytime soon just for subscribing.)

If there is an Achilles heel in the marketing strategy behind the CNS-10, it is the lack of continuous low-level VHF reception in many parts of North America. The unit is designed to utilize the VHF frequency range between 118 and 136.975 Mhz. Not everyone operates above FL 200 or near the larger airports, where ARINC assures a data link with its ground stations. Operators who cannot take advantage of existing reception areas will have to wait for new ground stations to be built, or until satellite links become part of the GLOBALink system. (The CNS-10 is built with current industry standard satellite communications interfaces.) ARINC has embarked upon an eight-year program of ground station expansion during which it hopes to install another 150 or so facilities to improve low- level reception. Schwartz points out that large areas of the country, such as the Northeast Corridor, already have reliable reception coverage above 5,000 feet. He says that ARINC's eventual goal is to have coverage from 5,000 feet or less "wherever aircraft typically fly in the United States."

In the meantime, the CNS-10's navigation capabilities alone are worth a look. The unit's GPS receiver works in tandem with an updatable Jeppesen NavData navigation database containing detailed information on airports and navaids worldwide. Pilots can create and store up to 50 flight plans containing as many as 40 waypoints each. The device can also be used to fly pilot-defined vertical navigation profiles when hooked into an aircraft's performance management system and autopilot. Installed in this way, it can also be used to execute published standard instrument departures and standard terminal arrival routes in the Jeppesen database. The CNS-10 will be usable for IFR enroute, terminal, and approach phases when fully certified, including precision GPS approaches as they become available. Precision GPS approaches will require an optional differential GPS receiver module, which will add about $1,500 to the unit's base price. FAA certification for VFR operations is expected by spring, and for IFR enroute, terminal, and precision approach use late this year or early in 1996.

First shipments of the CNS-10 won't occur until mid-1995. Launch customers will likely be the small to mid-sized corporate flight departments and commuter airlines which in the past have found ACARS to be a little too pricey for comfort. As ARINC makes good on its plans to expand the GLOBALink network, and as other elements of the Future Air Navigation System begin to firm up, the unit will likely find acceptance among a wider range of general aviation users.

Is the whole aviation world ready for the CNS-10? Probably not. Reality just hasn't yet caught up with highfalutin ideas like the Future Air Navigation System. But even so, the unit seems to make sense for those operators with a real need for the available features and who are willing to hold out for the rest. ARINC and Magellan no doubt hope to cultivate many more like them, all looking for that on-ramp to the information super highway in the sky.


Vincent Czaplyski, AOPA 690264, holds ATP and CFI certificates. He flies as a Boeing 737 captain for a major U.S. airline.