Originally Posted by
nwmgc
I have used upgrades on LH many times but this is never more expensive. Last year, for example, a return CW from LHR to Phoenix was about £3,500, but the upgrade I got with Airmiles, as was, instead cost £1,000 and 25,000 miles.
The key difference is that if you're MFUing on longhaul, you're buying a cash WT+ ticket and upgrading with miles/Avios from that. All WT+ cash tickets qualify, even the cheapest sale fares.
However, if you MFU on shorthaul, you're buying a cash Y ticket and upgrading with miles/Avios. And only the most expensive Y booking classes can be MFUd: Y, B and H.
So the value in upgrading from Y to J on shorthaul is very different from the value in upgrading from W to J on longhaul. In many ways, you're not comparing like with like even though in both cases you end up in the J cabin.