Yes, I used united.com exclusively. use the 30 day calendar so you can click through the weeks a little easier. there is no way to search for just NH F, unfortunately. Literally it is just brute force clicking on each day/box (happy to be corrected if I'm wrong!). There is nothing in the number or font color that will help you identify an F flight without clicking the box. Believe me, I used to think that it's useless to be checking so frequently and that nothing would ever show up but my recent experience has made me a believer. Or maybe I'm catching the flights after they are cancelled by someone else, but before they are going to ANA MC waitlisted people? I can't imagine that NO ONE from ANA MC waitlisted these award flights that I snagged. Who knows, I can only speculate. It is SO random.

Maybe this is super obvious and I don't even need to mention it. (it probably is). There is no F if there are only 3 columns displayed (economy, premium economy, business). If there is a F flight available, there will be 4 columns displayed across (not just 3). so as soon as you see 4 columns get excited, something is hiding somewhere.