Originally Posted by
xobile
Also, there's no way on the website or app, as far as I can tell, to tell when Tier miles are actually expiring. So you need to keep a calendar or transactional log of your tier miles earning dates.
Very true. I have a document on my PC which I keep updating after each flight with Guest miles, tier miles, and other details.
When I qualified for gold earlier this year, I had to be very accurate with my calculations of both miles and dates. I broke through the threshold with 50,180 miles on the final day of the rolling 12 month period. I also had to make one of my trips earlier than I really wanted as well as a mileage run detour But I'm glad I've done it now because my validity runs until end of March 2020.
The OP also needs to remember that no tier miles are earned with reward trips.
Mike