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".

Following the fatal Air India plane crash in June, the owner of the airliner is offering N216 million to the families of each person killed in the accident.

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.