[nfc-l] How do we know NFCs?

So as I'm starting to learn about NFCs the obvious question came to me: how do we know what we currently know? Do we typically infer ID features from daytime flight calls where we can visually verify our IDs? Or are night calls too different from daytime ones, meaning that we have/had to find

[nfc-l] How do we know NFCs?

So as I'm starting to learn about NFCs the obvious question came to me: how do we know what we currently know? Do we typically infer ID features from daytime flight calls where we can visually verify our IDs? Or are night calls too different from daytime ones, meaning that we have/had to find