Almost five years after the World's single most bloody act of terrorism - when hijacked aircraft were flown into the World Trade Center and the Pentagon building - aviation was again last month at the centre of another terrorism scare.
This time, UK security services foiled an alleged plot to bomb transatlantic airliners. 9/11 changed history, prompting the invasion of Afghanistan and the continuing US 'War on Terror' that led to the ousting of Iraq's Saddam Hussain.
But what has the lasting legacy of the 2001 attacks been on aviation? The industry has recovered strongly after a two-year nadir, but US airlines are still feeling the effects. And what of aviation security? Are we ever going to be able to terror-proof air travel?Flight International
experts have taken a look at all aspects of aviation post-9/11