Gary Leff points to a post by lucky, who caught a change in United’s terms and conditions: They’re eliminating the complimentary fare repricing policy. It’s the end of an era, and it’s shame to see it go.

What this used to mean: If the price of a ticket would drop in the time after you bought it, and if you were alert enough to notice the change, you could go online or call the airline and “refare” the ticket. You’d receive a voucher for the difference in the mail. Three years ago, I detailed the process here.

Repricing a ticket at a lower fare will now involve a reticketing fee — you’re cancelling the earlier “nonrefundable” ticket, paying a penalty, and using the credit from that transaction toward a new ticket.

United was the biggest airline to be doing free re-faring of an identical itinerary. Alaska, JetBlue, and Southwest still offer it for free. Most other airlines allow you to reticket, but there’s a fee of between $75 and $150. (It could still pay off if the fee is less than the fare difference.)

One warning to anyone repricing tickets, with fees or not: If you’re waitlisted for an upgrade, you’ll lose your place in line, and you may need to reapply. It’s a new ticket, so you’re starting fresh.

On the one hand, United’s abandonment of free refaring makes economic sense. Why give voucher refunds to people who have already paid for their (nonrefundable) tickets? The airline has your money, so there’s no incentive to give it back.

On the other hand, the voucher system is a way of guaranteeing future business. This is what the folks at Yapta, the service that tracks price drops after you’ve purchased the ticket, argued when they first launched their fare-drop tracking service:

Look, as an airline I still keep your cash. I’m taking a short-term hit, and over the next 12 months I have the opportunity to turn that $100 coupon into a $500 ticket. I’ve locked in your loyalty.

The voucher logic isn’t being abandoned entirely, after all. United and other airlines still give vouchers when there’s a customer service issue, and that voucher is designed to both show goodwill and lock in a future sale.

United’s change also means that they’re reneging on a benefit they offered as part of their “customer commitment.” As Gary points out, this was launched in order to ward off a passengers’ bill of rights, nearly a decade ago. Perhaps they’re planning to play the same card again: If pressure builds for another PBOR, then United can trot out a re-faring policy, just like they did last time.