Image copyright Other

It's been suggested women and children were not given priority for lifeboats when the Costa Concordia capsized. But are there rules governing who leaves a sinking ship first?

It's a famous moment in the Titanic story. "Women and children first!" went the cry.

It's too early to know exactly what happened in the final hours of the Costa Concordia. The captain has already had to deny allegations he left the ship before everyone had been evacuated.

And it has been reported that some male passengers ignored informal injunctions to wait until women and children had made it into the lifeboats.

How did the priority rule begin? This protocol started when HMS Birkenhead sank in 1852

"Women and children first" phrase coined in 1860

RMS Titanic disaster in 1912 popularised the rule

Only 20% of men on board Titanic were saved

It is not a part of international maritime law

Edwin Gurd, a retired police chief, told the Times. "We were keen for women and children to go first, and men if they had babies or families. A lot of men regardless of that were trying to save themselves."

But is the traditional maxim of women and children going first really part of the maritime rules?

Once passengers board a cruise ship, they are assigned a lifeboat according to where their cabin is, says Rob Ashdown, operations director at the European Cruise Council.

If there is an accident, as is the case with the Concordia hitting the rocks, it is up to the captain to decide whether to abandon ship. To signal the start of an evacuation, a loud alarm sounds ordering people to go to their muster station.

Costa sinking: How it happened Image copyright bbc Maps and stats on the grounded cruise ship

From this point onwards, ships have 30 minutes to load, launch and manoeuvre away the lifeboats, under regulations set down by the International Maritime Organisation. And there is no legal duty to allow women and children to board first, Ashdown says.

The evacuation of the troop ship HMS Birkenhead in 1852 is widely believed to be the first occasion of women and children being told to board the lifeboats first.

The ship was carrying nearly 500 troops and about 26 women and children. After the commanding officer's order for the soldiers to wait, all the women and children survived but most of the men died. The phrase "women and children first" is thought to have come later.

But there is one group who may receive preferential treatment today - disabled people with special mobility needs, Ashdown says.

"This idea of women and children first is just a convention there is for historical reasons," he suggests. "It may be appropriate in certain circumstances and cultures and not elsewhere."

When it comes to air travel, the point is immaterial as prioritising women and children in an evacuation would be impractical.

An argument could be made in relation to ships that men are generally likely to be stronger swimmers than women and therefore have a better chance of survival in the water. But today the argument is less about survival chances and more about treating people fairly.

Prof Ed Galea, an evacuation expert at the University of Greenwich, says orderly behaviour among passengers is crucial to a successful evacuation.

Image copyright Getty Images Image caption The women and children first rule caused more men to die when the Titanic sank

And having studied major disaster situations, including interviewing survivors from the World Trade Center, he says that people don't respond to these evacuations in the way that one might think.

"It's not like Hollywood, it's not like every man for himself. People behave quite selflessly. You'll find people screaming and crying but it doesn't mean they are panicking."

Usually people will help the most vulnerable to leave the scene first. It's not necessarily women, but is likely to be the injured, elderly and young children, he says.

It's too early to know in detail what happened during the Concordia evacuation. But it seems that the crew did an "exemplary" job and that most passengers behaved well, Galea says.

The real problem aboard the Concordia was the slowness of the order to "abandon ship", he argues. Crucial minutes were lost after the ship hit the rocks and reports suggest it was only once the ship began to heel that the evacuation began.

Once a ship heels at 20 degrees it becomes difficult to launch the lifeboats and after the Concordia began to tip over it was soon heeling dramatically.

"They had time," Galea says. "But as I understand it the evacuation didn't start until the ship had a serious heel."