FedEx has placed orders for four additional Boeing 767-300 freighters, bringing to 46 the number of outstanding orders that the package delivery company has for the type.
The 29 September order calls for one aircraft each to be delivered in 2017 and 2018, and two aircraft to be delivered in 2019, according to FedEx.
With the additional aircraft, the carrier will have a total of 56 767-300Fs in its fleet by 2019.
FedEx does not say what type of engines will power the four aircraft, but the company chose General Electric CF6-80C2 engines for 48 767-300Fs that it ordered in December 2011.
Boeing also offers the type with Pratt & Whitney PW4062 turbofans.
FedEx has so far taken delivery of six 767-300Fs.
The company says the aircraft are key to a fleet modernisation programme that is aimed at helping the company increase profit by $1.6 billion by the end of its 2016 fiscal year.
FedEx says its twin-engined 767-300Fs are 30% more fuel efficient and have 20% lower operating costs than the three-engined McDonnell Douglas MD-10 aircraft they are replacing.
Boeing now has 50 767s in its backlog, including 46 767-300Fs for FedEx and four 767-2Cs for the US Air Force. The latter are prototypes that will be converted into tankers to support certification testing of the KC-46A programme.
Source: Cirium Dashboard