Thank you for the reply.
The system will be installed on a boat with a KVH HD Dish. Normally, I would run seperate RG6 to each TV from the Air Antenna and use the TV Input to select Air vs Sat. With this setup, I always have backup if one of the systems fail.
I thought that I could eliminate the selection of Input if I could feed the Air through the AM21 and use the Direct TV Box to select channels. That would feed both souce signals thru the Direct TV Controller(Genie). Therefore, if the Controller fails, I loose both feeds. Not too concerned about this, but more about if I loose the sat feed beyond the memory capacity, the qustion is whether I would still be able to receive OTA broardcast on the Direct TV menu.