From hours at security to bulletproof cockpits: How 9/11 changed air travel

Not long after several planes were hijacked and used to wreak devastation on downtown New York and Washington, DC, a quarter of a century ago, air travel for millions of people all over the world changed beyond recognition – forever.

Two of the planes, hijacked by men linked to al-Qaeda, were flown into the Twin Towers at the World Trade Centre at the south end of Manhattan Island in New York City, causing the buildings to collapse and killing nearly 3,000 people.

A third hit the Pentagon, the building in Washington that houses the United States Department of Defense, while a fourth, believed to be headed towards the White House, crashed into an empty field in Pennsylvania after passengers on board wrested control of the aircraft from the hijackers.

It was the deadliest terrorist attack in US history, and all the planes had been boarded and seized with relative ease by the hijackers.

Here’s a look at how life for air passengers has changed since then.

Across the US, all air traffic was immediately grounded. Canada closed its airspace but exempted military, police and humanitarian flights, according to a government document.

In other countries, airports were closed and flights to the US were cancelled, causing many people to be stranded for days.

Canada reopened its airspace in stages, with domestic flights allowed to resume on September 12, followed by international flights a day later, and final restrictions removed the day after.