What is an airbus a340?

The A 340 is a long-range four-engine wide-body commercial passenger jet. It can fly over 15,000 kms carrying up to 500 passengers in economy configuration.

The A340, along with the DC-10 and the MD-11, were designed to compete with the Boeing 747 on long-range, high-capacity routes. It was derived from the smaller, two-engined A300. The A340 was drawn up at a time when FAA restrictions on two-engine planes were much stricter. According to the FAA, two-engined planes had a higher chance of engine failure, simply because they had fewer engines. The logic was that, if two engines failed, the plane was screwed. The A340, DC-10, MD-11, and B747 all have more than two engines; if two engines fail, the plane can still fly. 3- and 4-engined planes were permitted to fly the longer routes that two-engined planes were, historically, forbidden from flying.

Later on, the FAA realized that both engines on a two-engine airliner were very unlikely to fail at cruise altitude. So they introduced ETOPS, which allowed two-engined aircraft such as the B767, B777, A300-600R, A310, and A330 to fly much longer routes than before, and this pretty much ruined the A340, DC-10, and MD-11. The MD-11 became a failure, partly because McDonnell Douglas had stubbornly refused to break their trijet tradition. The A340 failed to adequately compete with its intended rival the B747, which, with decades of history and reputation, as well as its higher capacity, is still the preferred choice of most airlines around the world (even though it is far less efficient than the A340). "Mini-jumbos" like the B777 were also preferred over the A340 due to higher fuel efficiency. Smaller variants of the A340 also suffered from internal competition by the A330, the two-engined little sister of the A340.

So as an answer to your question, an Airbus A340 is a long-range, wide-body, four-engined airliner designed to be immune to the restrictions of the FAA on two-engine airliners, and to compete with the aging B747. It wasn't a failure like the MD-11, but it certainly did not meet Airbus' expectations, because its market was undermined by rapidly improving twin-jet airliners such as the 767, 777, and A330. Production ended in 2011.