Also from the article:
The airline has encountered headwinds of as many as 68 knots over the Pacific, vs. a more normal range of 40 to 45 knots.
The more permanent solution involves Boeing. US Airways has filed paperwork with the company to request an upgrade for the three 757s to the maximum weight limit of 250,000 pounds. It doesn't involve work on the planes, Seymour said, but is still costly.
It really came out to bad luck more than insufficient planning. Either way when Boeing certifies the 757 for the heavier weight than these problems will be a thing of the past.