If you know the flight number, can you fine the Tail number anyplace
Why? Did the tail number do something wrong? How much of a fine? 
OK, I see that the flight plans used to populate the database contain only the flight number or the registration number, but not both.
But for some airlines, this website does have both pieces of information. In those cases, are the two pieces of information not linked to each other at all?
For example, I might enter the registration number of a United Airlines aircraft. Flightaware will tell me where that plane is, but apparently not the flight number. But I know full well that Flightaware knows the flight number, because I can also search and find the flight using the flight number. I’m surprised that in this case, searching by one bit of information (flight # or reg #) does not give you the other bit of information.
You are correct. You can look up the tail number of certain airlines’ aircraft but it wont’ tell you the current flight number. And vice versa.
Thank you for the response.
Can I very humbly suggest that this might be a useful feature to someday add? I suppose I’m not the first person to ask this sort of question. I find this website to be much nicer to use than the other acars-based ones, and more complete over North America at least, so it’d be nice to only need this one.