rergarding a nav failure as an unlikely event to be treated like a stall or an engine failure.
There is nothing wrong with that - but then we have stall warners to help with that and we teach recovery from both and in the same way we should be teaching people to have some sort of back up and how to recover in the event of the GPS system failing - and not just carrying a second IPad or phone but a printed chart and plog, the big threat being a solar storm or deliberate interference taking out the satellites.