India, July 13 -- One month after losing his daughter, son-in-law and three grandchildren in the Air India crash, Anil Vyas struggled to find meaning in the preliminary investigation report that detailed fuel switches and flight recorder data but stopped short, as preliminary investigations customarily do, from offering a conclusive explanation for why 260 people died.

"What good is this report to us now? It won't bring back my daughter, her husband, or their children," said Vyas over the loss of Dr Komi Vyas, her husband Dr Prateek Joshi and their three children aged 5, 5 and 8.

The Aircraft Accident Investigation Bureau's 15-page preliminary report, released on Saturday, provided precise technical details about Flight 171's final mome...