We use global positioning systems (GPS) for our sat navs and our mobile phones, and it's used extensively in aviation and shipping navigation. But what happens when it's disrupted? GPS jamming, when the signal isn't able to get through - and spoofing - which tricks the receiver into calculating a false position, is happening more and more. We look into the impact on the transportation sector - and on our everyday lives. Produced and presented by Gareth Mitchell (Image: An airline cockpit. Credit: Getty Images)