Originally Posted by
united 1k flyer
can I redeem avios to cover surcharges from Chicago to London.
Not stricty no. There are two ways to use avios to reduced the amount of cash to be paid though.
With some avios bookings reduce the cash required by paying more avios. You will be shown the options in the quote screen - although I think it may only be certain long haul routes covered and may only be Y atm. Tbh it is not a good use of avios.
If paying a cash fare you can reduce the cash required by paying some avios. Again you will be shown this on the price quote page if available for your selected flights.