...Air Transport Services Group, Inc.'s (ATSG) Ba2 corporate family rating reflects the company's strong position as one of the world's leading providers of air cargo fleet leasing and related services, including crew, maintenance and insurance (CMI) services, as well as its strong earnings prospects, high margins and effective liquidity management. ATSG's earnings and cash flow have been resilient due to the strength of its cargo leasing business even as global air passenger traffic has significantly declined as a result of the coronavirus pandemic. A key credit challenge is ATSG's high customer concentrations; in 2019, Amazon (A2 positive) and DHL (owned by Deutsche Post AG, A3 stable) and the US Department of Defense accounted for 21%, 14% and 36% of revenues, respectively; this challenge is partially offset by the high credit quality of these customers and their long-term need for the services provided by ATSG. An additional challenge is ATSG's negative tangible equity, which limits the...