Forget the iceberg, human error was the real cause behind the sinking of the Titanic.

This surprising claim comes from the granddaughter of the ocean liner's second officer, Charles Lightoller.

"It just makes it seem all the more tragic," Louise Patten told London's Daily Telegraph on Wednesday. "They could easily have avoided the iceberg if it wasn't for the blunder."

Patten spilled the beans on the long-held family secret in advance of the release of her book, "Good as Gold," which is not about the Titanic but weaves in elements of the incident as she remembers it.

The mistake, which led to the sinking of the massive vessel in 1912 and killed 1,517 people, occurred when a steersman "panicked."

"The real reason why Titanic hit the iceberg, which has never come to light before, is because he turned the wheel the wrong way," Patten said.

Once the mistake had been made, she added, "they only had four minutes to change course and by the time [first officer William] Murdoch spotted [Robert] Hitchins' mistake and then tried to rectify it, it was too late."

Patten said her grandfather, the most senior officer to survive the sinking, covered up the error for fear it could ruin White Star Line, the company that own the ship, as well as the reputations of his fellow sailors.

Lightoller, however, was not present when the error occurred, Patten noted. He heard of it during a meeting afterwards.

After the Titanic struck the iceberg, she said, her grandfather believed the mighty vessel sank faster than it should have because J. Bruce Ismay, chairman of White Star Line, pressured the ship's captain to keep sailing.

"If Titanic had stood still, she would have survived at least until the rescue ship came and no one need have died," Patten said.

With News Wire Services

msheridan@nydailynews.com; or follow him at Twitter.com/NYDNSheridan