[SoftTalker]

And this is why you always use surrogate keys and not natural keys. No matter how much you convince yourself that your natural key is unique and will never change, if a human created the value then a human can change the value or create duplicates, and eventually will.

[dx034]

But that wouldn't help you here. The flight plan will come in with the code and you'll still have to resolve that to your keys.

[jjk166]

Sure, but that means you are putting in the infrastructure to resolve it, instead of assuming there will never be a need to.