The military transport construction business is about to witness a hiatus in airlifters of over 250-tonnes gross weight. Lower down the scale, the market dominance of turboprops is being challenged by new twin-turbofans, using high-bypass engines developed for commercial applications.

The principal programme at the top end of the scale is the US Air Force's modernisation and rationalisation of its fleet of 381-tonne Lockheed Martin C-5 Galaxies. By FY2017 some 52 (mainly C-5Bs built in the late 1980s) will have been reworked to C-5M Super Galaxy standard with GE Aviation F138-GE-100 (CF6-80C2) turbofans, modernised avionics and various airframe improvements. The 73 older C-5As will by then have been retired with Congressional permission. The C-5 was never exported, although in the friendlier climate of 1974 Iran offered the US money to restart production.

The C-5M attained initial operational capability in February 2014, when 16 of an eventual 18 had been delivered to the US Air Force's 9th Airlift Squadron ('Proud Pelicans') of the 436th Airlift Wing at Dover AFB in Delaware. Unrefueled, the C-5M can fly a 50-tonne payload over the 9,000 km from Dover to Incirlik AB in Turkey.

Today Russia's Military Transport Aviation (VTA) operates only a few 392-tonne Antonov An-124 Ruslans. These include five civil-registered An-124-100s based at Moscow-Chkalovsky, and five with the Bryansk-based 224th Flight Unit, which operates charters under the name TTF Air.

The VTA plans to have 20 Ruslans upgraded to An-124-100M standard by Aviastar in Ulyanovsk by 2020, after which it had hoped to buy 15 new-build An-124-200s. In November 2014 Aviastar announced the completion of the first batch of six upgrades, with improved avionics, flight deck instruments and aircraft systems. Some structural modifications extend fatigue life.

Commercial An-124s are now operated only by Volga-Dnepr Airlines (ten), Antonov Airlines (seven) and the Abu Dhabi-based Maximus Airlines (one). Up to six aircraft from the two larger civil operators are chartered by Nato, Finland and Sweden under the Salis (Strategic Airlift Interim Solution) programme, pending availability of the Airbus A400M.

It now appears unlikely that production of the 402-tonne Antonov An-124-200 will start in the foreseeable future. Under a 2013 agreement, 74% of this work was to be performed by Aviastar, where the final An-124-100s were built (for Volga-Dnepr and Polet Airlines). The remaining 26% was to have been done by Antonov.

The United Aircraft Corporation (UAC) would need an order for at least 60 aircraft to justify reopening the An-124 line at Aviastar. Volga-Dnepr has in the past shown interest in ordering 20. However, following the de-escalation in Afghanistan, there are doubts over the need for new-build large commercial freighters, as growing numbers of wide-body airliners provide vast underfloor capacity.

The 265-tonne Boeing C-17A Globemaster III production line will halt in 2015 with completion of the 279" aircraft (which includes some test airframes). The 223rd and last for the US Air Force was delivered in September 2013, but additional C-17s have been ordered by Australia (six, with two more planned), Canada (four), India (ten, with...