Ah, I think in my previous answer I misunderstood what you asked (but I leave it there in case anyone finds it useful).
Can you tell me how to recognise an uncontrolled airport please Dave.
So here's the answer to this question:
If you want to know if there is a tower frequency at a certain airport before even creating a flight plan, you can start PF3, select "Options #2", then "Add a NEW Facility Frequency", enter the ICAO code, press Enter, then click on "Show FS Freqs for this airport".
If there is no tower frequency, it is an uncontrolled airport. The correct term is even "nontowered airport", see https://www.aopa.org/-/media/files/aopa ... s/sa08.pdf
But you want a tower frequency (instead of using Unicom or Multicom), then you can add it here, too. One of the new features in PF3 compared to PFE