DISNEY

Carrie Fisher died Tuesday morning ... days after suffering a massive heart attack on board a flight from London to LAX ... a family spokesperson has confirmed.

TMZ broke the story ... Fisher was on a flight from London to LAX Friday when she suffered the heart attack 15 minutes before landing. People on the plane tell TMZ she appeared lifeless.

A passenger who's an EMT performed CPR on Carrie and once the flight landed, paramedics rushed her to UCLA Medical Center where she remained in intensive care until her death.   

The family had said she was in "stable condition" but we're told she was not responsive after her medical emergency.

Carrie had been on a publicity tour for her new book, "The Princess Diarist." The book recently made headlines because she wrote about having an affair with co-star Harrison Ford while shooting the original 'Star Wars' movies.