I am using the XRX with the Garmin 496. When I press the "on" button for the XRX, after a short ZAON sign on screen a second screen appears that offers me a choice between pressing the menu button for "ground" and the up button for "flight". I see no reference to this in the manual or on your website.

Please elaborate.

To set the unit in Ground Mode, turn the unit on and press the menu button during the startup sequence. To set the unit to Flight Mode, press the up arrow during this sequence. If no button is pressed during the startup sequence, the unit will automatically default to Ground Mode after 35 seconds.

XRX was designed to be used first in Ground Mode (this assumes you turn your XRX on while on the ground), then will automatically switch to Flight Mode on climbout. However, when connected to a Garmin or any other 3rd party device, you may want to get in the habit of pushing the up arrow after you turn the unit on to put it in Flight Mode directly. When you have the ability to see the relative relationship on a moving map, it becomes easier to differentiate between aircraft taxiing around you and someone, say, on final.

Ground Mode vs. Flight Mode is discussed in the "Understanding PCAS" chapter (page 14 of the most current manual). The most current versions are always available as a download in our Documentation section.