There’s an old adage in the world of flight – space flight, or otherwise.
"Test as you fly, fly as you test."
It’s pretty short and sweet and straight-forward. Don’t fly what you haven’t tested. Test exactly the ways you expect to fly.
In a big, round, wonderful world, it seems "funny" when we hear about problems related to living here. Problems like aircraft "flipping over" when they crossed the equator because they were adjusting to negative latitude – the coder hadn’t thought far enough ahead to think about crossing the equator.
This is the kind of problem that should be found in test, simulation, or in a thorough validation of design and implementation. The kind of validation that should be done with "other eyes" – not the eyes of the implementing entity. It’s far better to find these kinds of problems before you’re in the air, and lives are depending on everything to be Reliable.
That’s why I was surprised to read today about problems with the F22, apparently crossing the International Date Line caused the computers to shut-down.