It’s getting so that it’s scary to crank open the computer and open up the email bag.

Another Friday, another airline bankruptcy.

Frontier Airlines Holdings, Inc. today announced that, following an unexpected attempt by its principal credit card processor to substantially increase a “holdback” of customer receipts, which threatened to severely impact Frontier’s liquidity, Frontier and its subsidiaries have filed voluntary petitions for reorganization under Chapter 11 of the U.S. Bankruptcy Code.

We had talked about the shares of Frontier being in freefall here earlier this week. We formally placed the airline on our PlaneBusiness Titanic Watch last week. Yesterday shares of the airline took another dive, closing at $1.57.

Unlike the last several airline bankruptcy filings however, Frontier remains in business.

Frontier said it expects to continue operating its full schedule of flights, adding it will honor tickets and reservations as well as providing refunds and exchanges as usual.

“We felt that Frontier would be able to withstand the challenges confronting the U.S. airline industry, which include unprecedented and significant increases in the cost of jet fuel and the impact of the credit crisis in the financial markets, without seeking bankruptcy protection,” said CEO Sean Menke in a statement.

Just a note here on the increase in credit card holdbacks. We’ve seen this happen in the past — and it is something we can certainly expect to see again with other airlines that book their own reservations and find their cash reserves under scrutiny. (Clearly this does not apply to the bulk of regional airline flying.)

Ticker: (Nasdaq:FRNT)

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