Well, I think it's reasonable to see all three aeroplanes competing for the same segment of the big twin market. The A330 (especially the A330-300), A340 and 777 all more or less overlap each other from different directions, so you can't really draw sharp black and white lines in the capabilities of these airliners, despite the clever dots and lines on a manufacturer's graph. The 777 was introduced in response to Airbus's earlier initiative with the combined A330/340. I would have thought the 777 competed with the A330 in the slightly smaller and medium range segment of the medium-size wide body market, and with the A340 in the slightly larger and longer. This at least shows the 777's flexibility, which is increasing with the 777-300ER, and to a lesser extent with the -200LR. On the other hand, some A330s are flying long haul on very slightly thinner routes. Certainly, 777s and A330s compete directly on the north Atlantic and on routes from Western Europe to the Gulf, which is what I mean by overlap. In some sectors like these the A340 is ‘too much aircraft’ compared with the A330, which is a good 777 competitor.
Besides, there are a lot of similarities between the A330 and A340. So an airline can get two types for the cost of introducing one with a slightly better overall route range than optimally served just by 777s. Flightcrew licensing/flightdeck commonality, plus lease/finance costs, engine choice versus existing engines in a fleet, the manufacturer’s overall sales package and fleet commonality may all be important factors in fleet acquisition decisions, as much as the precise position of a plane in the market.