As usual, getting electronic data to an airplane in flight is nothing new, so long as you have a few hundred thousand bucks to spend. But transmitting useful and timely weather information into the cockpit at a price that makes sense for general aviation is brand new, and Bendix/King and Garmin have achieved it through very different technological paths.
There are two fundamental differences between the competing systems. The first major difference is that Bendix/King sends the data up from a network of ground stations, while Garmin gets its weather data downlinked from a constellation of satellites. Second, the Bendix/King weather is controlled and displayed on a dedicated piece of hardware that must be added to the panel, while Garmin integrates control and display into its hugely successful line of 530 and 430 comm/nav/GPS equipment.
At every step of the development process the two companies had to make different choices because of the fundamental technology involved. And now that the systems are certified and available, pilots will have to weigh the options and decide what is best for them.
The basic workings of the Bendix/ King datalink system are easy to understand. The company is installing a national network of transmitters, with most of them located at avionics shops. The VHF transmitters are linked via landline to a central weather data provider, and each station continuously transmits the data in a synchronized fashion. The KDR 510 datalink receiver continuously listens for a signal and, when one is received, begins to store all data in the airborne system's memory. In a few minutes all weather data available on the ground network is stored in the airborne system's memory and available for viewing. In the air you call up weather information for display just as you would open a file from the hard drive of your computer.