If 14% of the existing unredeemed airline miles are allowed to expire as United Airlines predict they will, the cost to consumers would be about $28 billion, according to the Chicago Tribune.

So how do you keep your miles from expiring?

There are lots of ways, the Trib lists a few:

Some ways to keep from losing those hard earned miles:

- Take a paid flight on the airline or an alliance partner (for example, a United frequent flier who takes a Lufthansa flight would qualify).

- Redeem miles for a flight, upgrade or even a magazine subscription.

- Use a credit card that awards frequent-flier miles. You can "buy a pack of gum for $1" and keep your account active, says United's Urbanski.

- Stay at a hotel that offers miles in the carrier's program. If you usually receive frequent-guest points in the hotel's program, you will have to forfeit them at least for one stay.

- Rent a car and ask to have miles credited to your program (though some car rental agencies will charge an added fee).

AirTran: 12 months
Continental: 18 months (though the airline claims not to enforce the policy)
Delta: 2 years
JetBlue: 12 months
Southwest: 2 years
United: 18 months
USAir: 18 months

How to save the faster-expiring miles [Chicago Tribune]
Use 'Em or Lose 'Em: Frequent Flyer Programs Accelarate Expirations [Five Cent Nickel]
(Photo:mrottler)