The plane knows its location, both from GPS and inertial tracking, but this information is not relayed elsewhere in real time. That would be perfectly possible. Ocean- going ships have had tracking since the 1980s – the limitation is not technology but a lack of legislation requiring it. 14 Volcanic fallout Air travel can be cancelled by volcanic activity. Glass-like ash particles melt in the heat of the engine, then solidify on the rotors. A clear-skies policy in an ash cloud may be inconvenient – but the risks of ignoring the ash are clear. 15 The wing myth For many years, we taught the wrong explanation for the way wings keep planes in the air. In fact, almost all a plane’s lift comes from Newton’s Third Law of Motion. The wing is shaped to push air downwards. As the air is pushed down, the wing gets an equal and opposite push upwards, lifting the plane. 16 Forget electric planes When we see ultra-light, experimental, electric planes, it’s easy to assume there will soon be clean, green, electric airliners, but it won’t happen any time soon. Aircraft fuel packs in a remarkable amount of energy. Batteries are much less efficient. To provide the same energy as a tonne of fuel would take 100 tonnes of batteries – and a 747 uses 150 to 200 tonnes of fuel. Unless battery technology is made vastly more efficient, electric airliners won’t get off the ground.