As part of its re-structure, FedEx - the world’s biggest air cargo carrier - is to withdraw 86 aircraft from the fleet of its air express arm, FedEx Express, in a move towards the operation of a more modern and fuel-efficient fleet. The operator said 10 aircraft would be retired immediately and it would bring forward plans for the permanent grounding of 76 others. The unit has been hit hard by a dip in volumes during the economic slowdown and a growing preference on the part of shippers to shift more and more of their shipments from air to cheaper transport modes, such as sea and road. The aircraft set for immediate withdrawal from service are two A310-200s, three A310-300s and five MD10-10s. FedEx Express is also bringing forward the retirement of a further 76 aircraft: 47 MD10-10s, 13 MD10-30s and 16 A310-200s, as well as 287 engines. Last July, FedEx announced the purchase of 19 B767-300 aircraft, an order that was in addition to an agreement with Boeing announced in December 2011 for the purchase of 27 new B767s for delivery between 2014 and 2018, and a delay in the delivery of a number of B777s. In March this year, it said it was buying up to 30 B757 aircraft from United Airlines for conversion into freighters.