US carrier Delta Air Lines said Friday that its regional subsidiary Comair Inc. would put its last plane in the air in September. \"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,\" said Delta Connection senior vice president Don Bornhorst in a statement announcing Comair will cease operations Sept. 29. The firm\'s overall strategy includes reducing the number of smaller, 50-seat jets from about 350 aircraft to 125 or fewer, he said. \"As a result of this reduction and changes to its customer-focused business strategy, Delta has made the difficult decision to cease Comair\'s operations,\" he said. The firm did not say how many jobs would be affected, but said the change \"will not result in any significant changes to Delta\'s network, which has enough flexibility to accommodate these changes.\" The subsidiary accounts for 1 percent of the firm\'s travel capacity, the statement said. Comair\'s hub Cincinnati \"will continue to be an important market in Delta\'s worldwide network,\" the company said.