I'm booked on UA102 (IAH-MUC) on March 22nd on an M fare and have requested an upgrade with a GPU. The flight is currently at J1 N1 C0 D0 Z0 ZN0 P0 PN0 PZ0 (flight status says Polaris capacity 30; booked 28). I think it's very safe to say that the odds of this upgrade happening are pretty low.
Does it make sense to attempt an SDC to get on a flight with better upgrade odds? united.com is currently offering itineraries that include the following TATLs (I realize that availability
may will change between now and the date of my flight):
UA30 EWR-MUC Polaris capacity: 30; booked: 24
UA960 EWR-FRA Polaris capacity: 39; booked: 34
UA952 ORD-MUC Polaris capacity: 48; booked: 40
If so, when does the SDC window open? My first leg is LAX-IAH at 11:40am on March 22nd. Does that SDC window open at 11:40am on March 21st? I see no restrictions on waived SDC charges for international flights; that is the case, yes?
I feel like I should know all this, but I rarely attempt such modifications to my itineraries.