This is what could happen if you try to use XM weather as airborne wx radar. 


This is a partial transcript from Harris in his IV last year in the Bahamas.

At 1032, the controller advised the pilot that there were intermittent areas of precipitation, "from moderate to extreme along your route of flight, deviations for the weather approved, when able cleared direct isaac [intersection]." The pilot responded, "i'm not showing any of that on my nexrad, i'm not sure where that area is, and ah, can you give me a better idea?" The controller then stated, "no sir, i really cannot, we don't have reliable reporting weather and our nexrad is inoperative today, and i'm just reporting this because we had an aircraft at eight thousand along your route of flight run into some moderate to extreme turbulence and heavy rain." The pilot then responded, "belay that, my , my nexrad is working out here, i'm going to deviate to the east now to get around that." The controller approved the deviation, which the pilot acknowledged.

At 1036:02, the pilot contacted the controller to tell her that he was in "severe, severe turbulence right here and heavy rain." The controller then cleared the pilot to make "evasive maneuvers," including changing altitude or "make a three-sixty, that's approved, just keep me advised." The pilot did not respond, and although there were a number of additional queries from the controller, there were no further transmissions from the airplane.

Ron Galbraith