Delta agreed to purchase 29 used Boeing 737-900ERs and to lease seven used Airbus A350-900s to help replenish its fleet after retiring about 200 aircraft as the coronavirus pandemic scuttled travel demand. Deliveries of the planes will be completed by the first quarter of 2022, pending unspecified closing conditions and modifications, Atlanta-based Delta said in a statement Tuesday. The aircraft are more fuel efficient than those they are replacing. The airline joined other carriers in using the pandemic-driven slowdown to rid fleets of older, costly aircraft and generally moved to larger planes that put more seats on routes and reduced expenses for each seat flown a mile. Delta shaved about two years off of its average fleet age, removed four aircraft types and set plans to retire another 200 planes in coming years. “These aircraft are an investment in Delta’s future,” CEO Ed Bastian said.<br/>