According to a press release issued by Mesa Air Group tonight, Delta Air Lines notified the airline on Friday that it intends to terminate the contract between Delta and Freedom Airlines, Mesa’s wholly-owned subsidiary.

According to the release,

“Delta seeks to terminate the Connection Agreement as a result of Freedom’s alleged failure to maintain a specified completion rate with respect to its ERJ-145 Delta Connection flights during three months of the six-month period September 2007 through February 2008. The notice issued by Delta is accompanied by a proposed temporary agreement pursuant to which Freedom would continue to provide Delta Connection services while the parties discuss the terms of a transition agreement. This termination does not affect Freedom’s CRJ-900 Delta Connection flying.”

Mesa, not surprisingly, said in the release that it intends to “vigorously defend its rights.”

So how many aircraft are we talking about? 36 Embraer 145s. Not chump change for Mesa. And no, the ERJ-145 is not an aircraft that is particularly in hot demand either — if Mesa has to try and unload them and/or find them new homes.

Ticker: (NYSE: DAL), (Nasdaq: MESA).