Delta_Aircraft_Cleaning HEPA filters Published 04/06/2020 at 800 × 534 in When will airlines start flying again? Delta Air Lines focuses on cleaning procedures for their fleet in response to the COVID-19 virus at the Delta TechOps facility in Atlanta, Ga.. Delta Air Lines focuses on cleaning procedures for their fleet in response to the COVID-19 virus at the Delta TechOps facility in Atlanta, Ga..