Traditionally frequent flyer miles are redeemed for capacity controlled awards. Airlines offer a limited number of seats for redemption that they expect would otherwise go unsold. And some travelers are frustrated they can’t find the seats.

But in general there’s always been the option to spend more miles in order to get any open seat. With United, it’s the “Standard” award rather than “Saver.” With Delta, this higher mileage option has been known as “SkyChoice.”

But Delta has announced that as of December 1, spending double the miles no longer gets you any seat. Instead, it just gets you access to more award inventory.

Now they’re not the only airline to do this. They’re following Northwest’s lead. But they’re still in the minority.

Rulebuster, Standard — or whatever you want to call them — awards are rarely useful (I prefer hunting and pecking for capacity controlled awards to get the most out of my miles). But when they are useful, they’re very useful.

It’s nice to know that with the mileage balances I have and with just a few hours notice I can get on just about any plane in the world and only pay the taxes (and perhaps a telephone or airport ticketing fee, grrr). It’s nice to know that if I really need to be somewhere, I can be. A last minute trip to a funeral, perhaps, where the tickets are prohibitively expensive.

United used to offer one of the great award values period in their higher-priced mileage chart — until last October, any business class seat from North America to Australia (no capacity controls!) was 150,000 miles. They’ve raised the price of that award, but at least they still respect the idea that more miles can buy you any seat.

Delta has raised the price of its SkyChoice awards, especially international premium class awards. Now that these awards will be capacity controlled as well, you might think they’d lower the price. Alas, I’m not that naive…