In a global investigation spanning India, the US, UK and Australia, reporterAshlee Mullany pieces together the final moments of Flight 171 using cockpit recordings, black box data and a world-first simulator recreation. 

Aviation expert Alastair Rosenschein told 7NEWS Spotlight: "Shutting down the engines at that point of the flight is going to only have one outcome." 

One of India's most respected aviation experts, Captain Mohan Ranganathan, said: "From some of the information that had been mentioned to me by pilots in India…they did say that the captain had been going through periods of depression, and he had taken medical leave." 

The crash could join a grim roll call. Ten years ago, Germanwings 9525 was deliberately flown into the French Alps by its co-pilot, killing all 149 on board, including Australian mother Carol Friday and her son Greig. 

Speaking exclusively to 7NEWS Spotlight, Carol's daughter Alex Friday said: "He mass murdered 149 people… including my brother and my mum.He ran them into a mountain. He took a machine and ran them into a mountain." 

Ashlee Mullany said "Pilot mental health is an uncomfortable but important conversation, particularly considering recent aviation tragedies. While the odds of a deliberate crash are still so low, the consequences are catastrophic. 

"In the case of the Germanwings crash, that pilot turned out to be one of the worst mass murderers in modern history and his actions are still felt acutely by the Friday family to this day."