Although the devil is in the detail, the broad idea is that you can enter an amount, pay that amount, and then see if your upgrade clears for Austrian’s Intercontinental routes as well as services to Amman, Astana, Baghdad, Baku, Erbil, Cairo, Tel Aviv, Tripoli and Yerevan.

Key conditions:

• Does not work on tickets purchased in China, India, Israel, Japan, Thailand, Turkey or the UAE
• Within 72 hours before departure Austrian will tell you if the request worked
• You must pay the amount you bid at the time of bidding
• The offer to bid is made once you have completed a booking as part of the booking process but can be requested via the My bookings page on the Austrian site
• It looks like the upgrade books in to P class

FAQ’s here