IT WAS a half minute that might have saved the world's largest passenger liner and nearly 1500 lives.

When the officer in charge of the Titanic was warned that an iceberg had been spotted in its path, he waited 30 seconds before changing course, a study has concluded.

The SS Titanic: 'Unsinkable'. Credit:AP

Had William Murdoch taken action immediately, the liner and 1496 lives might well have been saved.

The finding comes from a study for the centenary of the disaster next year. Investigators reappraised the 1912 Wreck Commission inquiry in light of research and evidence that has emerged since.