Here’s the reason you have to take your laptop out of your bag in the airport

Up there with fiddling with belts and removing boots, having to remove laptops and other electronics from inside bags is one of the persistent headaches of modern travel.

But why do airport security staff require you to remove laptops (and why do some airports allow you not to do it?)

The reason is simple, explains an Australian aviation expert, writing in The Conversation.

The machine your bags pass through is an X-Ray machine, and it can’t ‘see’ through certain parts of laptops, explains Doug Drury, professor/head of aviation, CQUniversity Australia.

Drury writes, "The main reason you have to remove your laptop from your bag is because its battery and other mechanical components are too dense for X-rays to penetrate effectively – especially if the scanning system is old. The same goes for power cords and other devices such as tablets and cameras."

"With these items in your bag, security officials can't use the screened image to determine whether a risk is present. They'll have to flag the bag for a physical search, which slows everything down. It's easier if all devices are removed in the first place."

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Some airports use newer 3D scan machines which can see if there are dangerous objects hidden underneath a laptop, for instance, Drury explains.

The 3D CT scanners are already in use in several European airports, including Amsterdam’s Schiphol airport and London City Airport, where you no longer have to remove laptops from bags.

Drury explains, "With newer multi-view scanning technology, security officials can view the bag from multiple angles to discern whether something is being covered up, or made to look like something else. For instance, people have tried to mix gun parts with other components in an effort to pass checked baggage screening.

"Some airports have upgraded 3D scanning that allows travellers to pass their bags through security without having to remove their laptops. If you're not asked to take out your laptop, it's probably because one of these more expensive systems is being used."

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