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VX has offered bid for upgrades for least two years. Originally it used third-party services (Plusgrade and SeatBoost) but now uses email solicitation.
I don't know how flights or pax are selected or if it is possible to opt in. I've not heard of it being done for MCS.
The offers require a minimum bid, about double the elite MCS>F price.
My guess is that bids are solicited on flights with lots of unsold F. If VX can entice a few F sales at double the elite upgrade price, that's OK with me.
Last edited by dayone; May 20, 2017 at 2:40 pm
Reason: Clarity.