Morgans wrote:

"Newps" wrote

I understand that but when it's working effectively the market for XM
will shrink to near nothing.


I just can not believe that XM will be without merit, no matter when ADS-B
comes fully on line. Ground based systems will still be hard to get, when
low in hilly terrain, and in parts of the country that do not have a high
concentration of transmitters.

Look at the coverage maps now on the ADS-B website. I don't think
coverage will be a problem. The other thing going for it is the FAA
will be phasing out ATC radar to use ADS-B so I believe the coverage
issue is moot.