A long-range four-engine widebody jetliner made by Airbus from 1991 until 2011.

The Airbus A340 is a widebody quadjet airliner produced by Airbus starting in 1991, with its maiden flight coming later that same year and its entry into service taking place in 1993; however, its development process (along with that of its two-engined sister model, the , which, despite its lower model number, was introduced a year after the A340) dates back to the mid-1970s, when it was first conceived of as a larger, long-range derivative of the earlier . Although was already a thing by the time the A330/40 family was being developed (it had come along in the late 1970s, just in time to save the A300 from an early grave), twinjets were still limited to routes passing no further than 90 to 120 minutes' single-engine flying time from suitable diversion airports, which meant that many long transoceanic routes were still off-limits to twins like the A300 (and the A330, when it was introduced); consequently, Airbus developed the four-engine A340 so that they could offer an airliner immune to these restrictions.

Unfortunately, by the time the A340 entered service, 180-minute ETOPS had already been introduced, which lessened the A340's edge, even on intercontinental routes; as a result, only 380 A340s were ever built (377 of which were delivered to airlines; of the remaining three, two were retained by Airbus and the third was wrecked in an accident during ground testing before it was to be delivered), as compared to 1,439 A330s and counting. The introduction of 240-minute-and-beyond ETOPS, starting in 2007, was the final death knell for the A340, which ceased production in November 2011; it would eventually be replaced by the , beginning in 2015.

Jetliners competing with the A340 include, aside from the A330 and A350, the , , , and, for the A340-600, the .

There are four major versions of the A340, in two families:

Original versions

These two versions entered service in 1993. They are virtually identical to the corresponding variants of the A330; the largest difference - aside, of course, from having four engines (General Electric/SNECMA [CFM International] CFM56s), rather than the A330’s two - is that the A340 has an extra bulge under its wings to prevent the airflow around the wings from interacting with the outboard engines to place undue twisting loads on the wings.

  • The A340-200 is the smallest A340 (seating a maximum of 261 passengers), and has a range of up to 15,000 km (8,100 nmi). It proved to be too expensive for an airliner of its size, and only 28 were produced. None remain in airline service (the last being retired in July 2017), although a few are still used as government and VIP transports.
  • The A340-300 is the most-produced variant, accounting for 218 of the total production run. It typically seats around 295 passengers, although it can carry up to 375 in a high-density configuration. Being larger and heavier than the A340-200, it has a correspondingly-shorter range, maxing out at 13,700 km (7,400 nmi). 96 A340-300s remain in airline service as of July 2018.

Stretched, longer-range versions

These versions were introduced into service later, in 2002-3. They use a stretched version of the A340-200/300 fuselage, plus new, larger wings to lift this heavier fuselage (and hold more fuel), and more powerful Rolls-Royce Trent 500 engines to push the whole thing along.

  • The A340-500 was, at the time it was introduced, the longest-range commercial airliner in the world, being able to fly up to 17,000 km (9,000 nmi) nonstop. Unfortunately, like the A340-200, its long range, for most operators, didn't justify its reduced passenger capacity (typically 313 passengers) and its almost-A340-600 pricetag, and only 34 were built; of these, just three remain in commercial service.
  • The A340-600 is the largest A340, seating 380 passengers in a typical cabin configuration, and able to cram in up to 440 in a pinch. It was also, at 75.36 m (247.24 ft), the longest commercial airliner in the world until the Boeing 747-8 first took to the air in 2010. Despite its size and weight, its range is still a quite respectable 13,980 km (7,550 nmi). 97 were produced, of which 60 remain in service.

For more information about the A340, see its Wikipedia page.