Terror laid bare

But when in 2003 a parliamentary committee asked a witness from the Department of Transport whether there had ever been a terrorist incident on an aircraft in Australia, nobody could think of one. (There had been an unsuccessful hijacking attempt of a flight between Melbourne and Launceston in May that year, but the hijacker was suffering from severe paranoid schizophrenia. Hardly a professional jihadist.)

So even if full body scanners in every airport in the country halved the risk of terrorism, half of bugger-all is still bugger-all.

Human beings are terrible at assessing risk. In the past 12 months, there have been more than 1,500 deaths on Australian roads. By contrast, over the past decade, 469 airline passengers died from bombings, hijackings or pilot shootings in the entire world. More than half of those fatalities occurred on September 11. The noughties were the second-safest decade for air travel since the 1950s, and there are a lot more passenger flights now.

Perhaps it's all that security that makes flying so safe. But security specialist Bruce Schneier argues that there are just two truly effective protections against terrorism on airlines. The first is reinforced cockpit doors - without access to the cockpit, it's hard to turn a plane into a flying missile. Since 2001, pilots do not open that door.

The second is us. Right now, the strongest defence we have against airplane hijackings or bombings isn't terrorist no-fly lists or body scanners. It's the passengers who now know they shouldn't passively comply with the demands of terrorists, and who know the guy doing chemistry in the bathroom should not be left in peace.

The Christmas underpants bomber was scary, but security worked exactly as it should have. He couldn't get a "good" bomb on board, so he tried to detonate a bomb so awkward it required 20 minutes of preparation in the toilet. And he couldn't get it to work. He was quickly subdued by passengers when his pants caught on fire.

The Australian attempted hijacking was also defeated by passengers.

Back in 2005, then immigration minister Amanda Vanstone was candid about the absurdity of airline security. With obvious enthusiasm, she posed this hypothetical to a private audience: "If I was able to get on a plane with an HB pencil - which you are able to - and stabbed the HB pencil into your eyeball and wiggled it around down to your brain area, do you think you'd be focusing?"

Most terrorist plots are discovered through quiet investigative work, and foiled long before they are anywhere near ready, although we still haven't dealt with the "Amanda Vanstone driving an HB pencil into your eyeball" threat. So the risk of airline terrorism will never be zero. But let's try not to panic.