CINCINNATI (AP) -- Delta Air Lines is shutting down its shrunken, 35-year-old regional carrier Comair at the end of September as it switches to bigger jets and it is sending termination notices to employees.

Comair is down to 290 flights a day. More than 1,000 of the carrier's remaining 1,700 Comair employees are in the Cincinnati and northern Kentucky region, some 700 of those in Kentucky.

Comair has slashed its fleet, flights and workforce in the last seven years. Delta said the smaller regional planes are expensive to fly because they are not as fuel-efficient and cost more to maintain as the fleet ages.

Comair handles only about 1 percent of Atlanta-based Delta's flying, so the closure won't result in significant changes to Delta's network. Delta also said it won't mean fewer flights out of Comair's base at Cincinnati/Northern Kentucky International Airport. Besides Cincinnati, Comair also has hubs in Detroit and at New York's JFK and LaGuardia airports.

Shares of Delta Air Lines Inc. fell 9 cents to $9.33 in midday trading Friday.