I know this is not your point for the last paragraph, but have you read about the C-130 complete navigation system failure while trying land below sea level at

I know this is not your point for the last paragraph, but have you read about the C-130 complete navigation system failure while trying land below sea level at the Dead Sea? :) https://news.ycombinator.com/item?id=14409950 https://news.ycombinator.com/item?id=14409950