Originally Posted by
platbrownguy
If you have an expertflyer subscription it's not hard to use the BXP1s. Just set alerts, search around, etc. I've had no trouble booking JFK-LAX/SFO flights (either in Y, to confirm into C; or in biz, to confirm into A) that I could confirm the upgrade on at the time of booking.
Of course, simply trying to use them on existing reservations is a fool's errand.
I've had reasonable luck using them on SFO-JFK reservations that didn't have C availability at time of booking, by picking flights with J cabins that were undersold relative to surrounding dates and times. I just put ExpertFlyer alerts on the flight and cross my fingers. I have an upcoming two-person SFO-JFK reservation on which I was able to confirm BXP1 upgrades months after I booked it with this method.