It seems many people here are looking at the weather as a probable cause.
I have flown the A340 (but not A330) for many years in similar tropical weather on the other side of the world , Africa , Far East and India where the same weather pattern exists.
Towering CB's , Massive CAT's , rain and precipitation of huge magnitudes are quite common. No pilot in his right frame of mind will attempt to penetrate the worst of such weather and in this day and age , the pilot has plenty of information and warning to prevent him from going through such weather.
If , and I say a BIG IF , weather is considered as a major factor , then surely there must have been a failure in the cockpit mainly the weather radar, that sent the crew into a very active cell. OR , the radar failed to pick up these activities !!!!
Our old A 340's ( no more flying) had a problem with weather radars. If I can remember rightly , we had problems with the shallow band of vertical coverage of the radar. It could not pick up the significant weather when it was tilted beyond certain degrees , up or down. Apparently it was a software issue , which was supposed to be fixed in the newer generations of A340 and A330.