Delta Airlines, soon to be the world's largest air carrier, has made some changes to its bag of fees.

1. It's adding a first checked bag fee of $15. Premium class passengers, full fare coach passengers, and upper tier frequent flyers, are exempt. Effective Dec. 5, 2008.

2. It's cutting in half its second checked bag fee, from $50 to $25. (If you've bought a ticket for travel on or after Dec. 5 you'll pay the previous rate).

3. Fees for cashing in frequent flyer miles, ranging from $25 to $100 on Delta/Northwest, are eliminated, effective immediately.

4. Northwest's "coach choice" premium seat fees will be added to Delta flights ($5 to $25 each way for certain aisle and exit row seats offering more leg room or easier access). Frequent flyer elites can book these seats at no charge.

5. As stated in a previous post, Delta has increased its in cabin pet fee from $100 to $150 each way.