Compared with the A340-300, the A340-600 features a 9.07m (35ft 1in) stretch (5.87m/19ft 3in ahead of the wing and 3.20m/10ft 6in behind), allowing it to seat 372 passengers in a typical three class arrangement. This gives Airbus a true early model 747 replacement and near direct competitor to the 747-400, with similar range, but, Airbus claims, better operating economics (per seat).

The A340-500 meanwhile is stretched by only 3.19m (10ft 6in) compared with the A340-300, and so seats 313 in three classes, but it has a massive range of 15,740km (8500nm), which makes it the longest ranging airliner in the world, capable for example of operating Los Angeles-Singapore nonstop.

The two new A340 models share a common wing. The wing is based on the A330/A340's but is 1.6m (5.2ft) longer and has a tapered wingbox insert, increasing wing area and fuel capacity. Both models feature three fuselage plugs. The other change to the A340 airframe is the use of the A330-200 twin's larger fin and enlarged horizontal area stabilisers. To cope with the increased weights the centre undercarriage main gear is a four wheel bogie, rather than a two wheel unit.

Both new A340s have a high degree of commonality with the A330 and other A340 models. They feature Airbus' common two crew flightdeck, but with some improvements such as LCD rather than CRT displays and modernised systems.

The A340-500 is powered by four 236kN (53,000lb) thrust Rolls-Royce Trent 556 turbofans, and the A340-600 by the 249kN (56,000lb) thrust Trent 556.

The commercial launch for the A340-500/600 was at the 1997 Paris Airshow, the program's industrial launch was in December that year when Virgin Atlantic ordered eight A340-600s and optioned eight. First flight of the A340-600 was made on April 23, 2001. After a 1600 hour flight test program, certification was received on May 29, 2002. Virgin Atlantic took delivery of its first A340-600 at the 2002 Farnborough International Airshow, and began commercial services in August.