Air India's deadly plane crash that killed at least 270 people has triggered a wave of speculation about what led to the world's worst aviation disaster in a decade, but authorities are slowly narrowing down areas of investigation.

Tragedy struck this week when a plane crashed in the city of Ahmedabad just shortly after takeoff, leaving investigators and aviation officials with many questions.

King Charles has asked the Royal Family taking part in the Trooping the Colour parade to wear black armbands, as a mark of respect to the victims of the Air India plane crash, Buckingham Palace said.