Joe Carnahan - Neeson Used Grief Over Richardson For Emotional Scene

The film focuses on a group of plane crash survivors who are stranded in the Alaskan wilderness, and Neeson plays Ottway, whose spirits are kept alive by the thought of reuniting with his wife.

In a crucial scene, his character pens a heart-wrenching letter to his loved one - and Carnahan suggested Neeson should think of his late wife Richardson to summon up the appropriate emotions.

He tells Empire magazine, "There's a letter that Ottway's writing to his wife, and I said, 'Write it to Natasha.' I wanted it to come from an innermost place... I think it's one of Liam's finest performances. It might honestly be his best."

Richardson died in 2009 after suffering a head injury in a skiing accident in Quebec, Canada.