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After reporting a 10% increase in passenger revenues for the month of December on Friday morning, Delta Air Lines Co. (NYSE: DAL) raised its estimate for the company’s fourth quarter operating margin from 5.5% to a new range of 8% to 9%. Passenger unit revenue is expected to rise 3% compared with the year-ago fourth quarter while costs are expected to rise about 2%.

Delta had projected a gain of 7% to 9% for the month of December, but the timing of the Thanksgiving holiday probably pushed revenues associated with holiday travel into the first few days of December. Fuel costs were also $0.03 a gallon below the company’s expected range of $3.03 to $3.08.

In late October, United Continental Holdings Inc. (NYSE: UAL) projected that its unit revenues would decline by 1.2% to 1.4% for the full 2013 fiscal year and that fourth quarter revenues would rise by 2.5% to 3.5%. United’s estimated its fuel costs at $3.10 to $3.15 per gallon.

American Airlines Group Inc. (NYSE: AAL) and Southwest Airlines Co. (NYSE: LUV) have not published revenue data or projections.

While Delta’s news is spreading good cheer and rising share prices today, all the airlines are wary of a coming increase in a federal tax they pay to support the U.S. Transportation Safety Administration (TSA). Congress approved an increase to the fees paid to the TSA as part of the budget deal it reached last month.

What’s got the airlines stirred up is that a new tax might be assessed on the baggage and other fees that the airlines now charge passengers. Those fees have generated $31.5 billion in revenues for the airlines over the past seven years according to the Bureau of Transportation statistics, more than half that total from baggage fees.

The airlines argue that a typical $300 round-trip ticket already includes $60 in federal taxes and that will rise unless the airlines’ lobbyists can convince Congress to back-off. The budget deal raises the TSA fee from $2.50 per one-way trip segment to a maximum of $5.00 to $5.60. The increase is expected to take effect in July and raise about $12.6 billion over 10 years.

For Delta, though, Friday is seeing the company’s share price rise more than 5% in the noon hour, to $29.13 in a 52-week range of $12.55 to $29.44.

United is also getting a boost, up about 4.4% at $39.39 in a 52-week range of $23.62 to $40.19.

American Airlines is up nearly 5% at $26.62 in a range of $12.70 to $27.20, and Southwest Airlines is up about 2% at $19.25 after posting a new 52-week high of $19.31. Southwest’s yearly low is $10.73.