Delta Air Lines Inc said its Comair subsidiary will cease operations after Sept. 29 as the airline reduces its exposure to low-margin regional flying. 

"While regional flying has and will remain a key component of Delta's network, customer expectations and the unit costs of regional flying have evolved,'' Don Bornhorst, senior vice president of Delta Connection, said in a memo to employees. The company recently said it plans to reduce the number of regional jets in its network as it adds more to its mainline operations.

Comair's shutdown will not result in major changes to its network, Delta said. 

Cincinnati-based Comair accounts for about 1% of Delta's network capacity.