Delta Air Lines’ regional subsidiary, Comair, will cease service on Sept. 29, falling victim to its parent company’s plan to slash more than 200 50-seat aircraft from its operations within the next few years.

Cincinnati-based Comair primarily serves Cincinnati/Northern Kentucky International Airport, Detroit Metropolitan Wayne County Airport, New York LaGuardia and John F. Kennedy International airports as a Delta Connection carrier, operating about 400 daily flights.

Comair accounts for just 1% of Delta’s capacity—having undergone significant cuts in recent years—and Delta says it does not plan to make any “significant changes” to its flight schedule or locations served. The mainline carrier is not saying which regional airline partner will take the place of Comair in markets that Delta wants to continue serving with regional jets.

Delta plans to reduce the overall number of 50-seat regional jets in its network from nearly 350 to 125 by the end of 2015, and says Comair operates some of the oldest 50-seat aircraft in the Delta Connection fleet with the highest unit cost per flight hour.

Comair President Ryan Gumm today told employees Delta decided to remove the remaining 16 50-seaters still in service at the regional subsidiary from the Delta network, a decision that would leave the airline with a fleet of just 28 CRJ700 and CRJ900 aircraft. “This further reduction of Comair’s active fleet will only create higher unit costs, which equates to a business model that is no longer sustainable in this competitive regional environment,” Gumm told employees.