Q. For years I have been an Executive Premier flyer on United.  I make two trips a year to London from Washington, D.C. and I would buy a coach ticket at prices ranging from $1,000 to 1,400 and would spend 20,000 miles each way to upgrade.  About five years ago the number of miles required to upgrade went up to 30,000 each way. But this year it’s a brand new world.  On my first trip I was shocked when United wanted $1,400 for an economy class ticket for March travel from D.C. to London and then wanted 20,000 miles and a fee of $500 each way to upgrade.  Also odd, I was able to buy a one-way business class ticket at $2,200 for a trip in July.  When did United add these co-pay fees and do all airlines charge them?

A. United started charging co-pays, in addition to frequent flyer miles for upgrades, in January of 2010. American, Continental, and US Airways also charge co-pays; Delta does not, but you can only upgrade more expensive economy class fares to business or first on Delta. During the summer months, when business travelers tend to fly less, you will find heavily discounted business class fares to Europe, and it makes no sense to pay $1400 or so, plus $500 in co-pays, plus 30,000 miles to upgrade; you’re much better off just buying the discounted business class ticket.