Clearly the investigators will have to establish all the facts before coming to any conclusions and all accidents are caused by a combination of circumstances rather like the proverbial block of cheese with holes in it - when they all line up a major event like this occurs.
As a pilot myself I feel for the flightcrew in this accident and cannot imagine what they are going through. The popular media like to portray the idea that everything is "black and white" but those that are experienced know that there are many shades of grey! Flying is "risky", we are all striving to minimise the risk but if we constantly divereted whenever the weather was "marginal" we would never get anywhere!
I seem to recall on the A320 series (different type I know but many similarities to the A340) that one went off the end at Ibiza circra 5 years ago which was associated with a failure of the BSCU (Brake Steering Computer..I think!) and also there was a near miss somewhere in Germany not long after the type had been in service where the logic of the speedbrake operation was a partial cause of a very close overrun - anyone got any details on these for comparison?
No doubt there will are lessons to be learned from this accident but we must be thankful that all got away unscathed. It is also a timely reminder that fire is one of aviator's major hazards.
Finally, well done to the cabin crew for doing an excellent job in getting them all out.