After 3 months of perfect flying, suddenly I get 'ultrasound emergency' and I can't take off - gets up about 2ft then lands and that's it. Have read the above - did'nt help at all, Have reset, shut down everything to reboot. Still the same. Help!
Most likely you need a new nav board. But... before you blow some $$$ be sure to completely remove all of the nav board connections from the main board and then reassemble and see if that helps. Sometimes the errors are caused by a bad connection to the nav board.
For me however I was getting that error massage out of the box and it eventually led to a bad crash that also broke my main board. After replacing both my main board and nav board I have never received the same error, and I'm loving it.
iPhone 4 IOS 6
Firmware 2.1.12 and never going to change...EVER