Give them massive numbers, that’ll impress them. The Secret Life of the Long Haul Flight (Channel 5) is one of those documentaries that does that, right from the off: each year, 300 million passengers fly more than 6bn miles on long-haul flights. Some of them on an Airbus A380, which costs £280m, carries 484 passengers, is 73 metres long, 25 metres high …