The families of the victims of the Air India plane crash in Ahmedabad last month have accused the Tata Group-owned airline of "forcing" them to make financial disclosures under the "threat of receiving no advance compensation".

Three weeks after an Air India Boeing 787 crashed, investigators are still piecing together what went wrong. In the meantime, aviation safety experts have begun to narrow their thinking.

A controversy has erupted over allegations by families of the Ahmedabad plane crash victims that they were pressured to make financial disclosures. Air India has denied the charges.