Originally Posted by Often1

UA/CO is simply leading the pack, but DL, AA will follow shortly. With capacity cutbacks and increased demand for F and Y/B, the availability of discount buckets is radically dropping. Those are the buckets which need to go if carriers are to return to and maintain profitability. The one exception is agressive marketing of corporate discounts where UA/CO can obtain vast (enforced) customer loyalty without having to do much for individual pax.

If you look at Y/B fares over the same time periods, you will see that they have increased along fuel price lines, but are not skyrocketing like the discount buckets.