Originally Posted by wylek

Similar data points from the past week. Yesterday, an EXP agent quoted an "upgrade surcharge" of $427.50 to apply a systemwide (PE to J) to an EU-LHR-USA PE (P class) ticket with BA-operated, AA-marketed flight numbers. After some pushback, the agent provided the rate desk's explanation: at the start of 2024, BA now requires AA to collect all additional carrier-imposed fees/surcharges when processing a systemwide upgrade on a BA flight.

The problem in this latest example is that +$427.50 exceeds the differential in carrier-imposed fees between PE and J. A PE fare with a BA-operated transatlantic flight includes $169.90 in carrier-imposed fees, while a J fare includes $481.30 -- that's a difference of only $311.14. The taxes on the two fares are the same. (Note that there is no APD involved here because the origin is ex-EU, not ex-UK).

The agent refused to explain the details of how the charge was calculated. The quote is different every time you call, and AA is not interested in being transparent about it.