Thanks for that interesting link
john_tullamarine. While it doesn't answer my query about what happens if the picocell dies, it raises further issues:
Strauss: There's good news and bad news about pico cells. The good news is that with the pico cell on board, most cell phones go to low power.
The bad news is that it's highly likely, for example, that Sprint may win the contract [to provide in-flight cell phone service] with United and Verizon winning the contract with US Air, and you'll have different services on different aircraft. The passenger is not in tune with what service the airline has, so he's going to turn on his phone and try to use it. And if it's not compatible, no one has convinced me that the pico cell will be able to tell that person, "You can't make a call here."
Avionics: The phone won't be low power?
Strauss: Right. His phone will be screaming. We had clear, concrete rules in the past--you cannot use your cell phone during flight, period--and people still used them with some consistency. I guarantee you that with pico cells, everyone will try to make calls. And with what we talked about with the intermodulation and what NASA has found, it's a bad path to go down, unless we're doing some other things to monitor the situation.