The proposed all-cargo version of the Airbus A350 XWB will offer Boeing MD-11F levels of payload and volume, but development is unlikely to begin until work on all the passenger models is completed.

Airbus plans to use the A350-900 variant as the basis for the freighter, which will follow the passenger versions of the twinjet that are due to enter service in 2013 (-900), 2014 (-800) and 2015 (-1000). A -900R extended-range version is also planned.

Airbus says that as now proposed, the A350-900F will have a similar payload and volume to the MD-11F, and a range of 9,250km (5,000nm).

While early work on the freighter has determined its internal volume and range, more detailed design studies are not expected to start until the -1000 passenger variant's development is at a very advanced stage.

"Work on the freighter will depend on market demand. We want to get the -1000 done first," says Alain Pardoe, product marketing director for the A330/A340/A350. He declines to comment on when the A350F's substantial design work might begin.

According to Boeing, the MD-11F has a gross payload of 91,700kg (202,000lb) and its main cabin will hold up to 440m³ (15,500ft³) of palletised cargo, while its lower compartments can contain an additional 158m³ of bulk cargo.

The largest freighter currently offered by Airbus is the 64t payload A330-200F, which will enter service at the end of 2009, so the development of a 90t payload A350 freighter will significantly bolster the airframer's cargo aircraft armoury.