SPEAKER_00: Amazing, fascinating stories of inventions, ideas and innovations. Yes, this is the podcast about the things that have helped to shape our lives. Podcasts from the BBC World Service are supported by advertising. Hello, it's Tim Harford here. Before we get started on the invention of radar, I wanted
SPEAKER_01: to let you know that at the end of this episode, I'll be telling you how you can help me choose a 51st thing. That is, if you're listening to this in August or early September 2017. Details coming up in approximately nine minutes.
SPEAKER_02: 50 things that made the modern economy with Tim Harford. In Kenya's Rift Valley, Samson Kamau sat at home, wondering when he'd be able to get back
SPEAKER_01: to work. He should have been in a greenhouse on the shores of Lake Naivasha, as usual, packing roses for exports to Europe. But the outbound cargo flights were grounded, because the Icelandic volcano Eyjafjallajökull had, without sparing the slightest thought for Samson, spewed a cloud of dangerous ash into Europe's airspace. Nobody knew how long the disruption might last. Workers like Samson feared for their jobs. Business owners had to throw away tons of flowers that were wilting in crates at Nairobi Airport. As it happened, flights resumed within a few days. But the interruption dramatically illustrated just how much of the modern economy relies on flying, beyond the 10 million passengers who get on flights every day. Eyjafjallajökull reduced global output by nearly $5 billion. You could trace the extent of our reliance on air travel to many inventions. The jet engine, perhaps, or the aeroplane itself. But sometimes one invention needs another to unlock its full potential. For the aviation industry, that story starts with the development of the death ray. No, wait. It starts with an attempt to develop the death ray. This was back in 1935. Officials in the British Air Ministry were worried about falling behind Nazi Germany in the technological arms race. The death ray idea intrigued them. They'd been offering a £1,000 prize for anyone who could zap a sheep at 100 paces. So far, nobody had claimed it. But should they fund more active research, was a death ray even possible? Unofficially, they sounded out Robert Watson-Watt of the radio research station. And he posed an abstract maths question to his colleague, Skip Wilkins. Suppose, just suppose, said Watson-Watt to Wilkins, that you had eight pints of water, one kilometre above the ground. And suppose that water was at 98 degrees Fahrenheit and you wanted to heat it to 105 degrees. How much radio frequency power would you require from a distance of five kilometres? Skip Wilkins was no fool. He knew that eight pints was the amount of blood in an adult human. 98 degrees was normal body temperature. 105 degrees was warm enough to kill you, or at least make you pass out, which, if you're behind the controls of an aeroplane, amounts to much the same thing. So Wilkins and Watson-Watt understood each other and they quickly agreed that the death ray was hopeless. It would take too much power. But they also saw an opportunity. Clearly the ministry had some cash to spend on research. Perhaps Watson-Watt and Wilkins could propose some alternative way for them to spend it. Wilkins pondered. It might be possible, he suggested, to transmit radio waves and detect, from the echoes, the location of oncoming aircraft long before they could be seen. Watson-Watt dashed off a memo to the Air Ministry's newly formed committee for the Scientific Survey of Air Defence. Would they be interested in pursuing such an idea? They would indeed. What Skip Wilkins was describing became known as radio detection and ranging, and then as radar. The Germans, the Japanese and the Americans all independently started work on it too. But by 1940 it was the Brits who'd made a spectacular breakthrough. The resonant cavity magnetron, a radar transmitter far more powerful than its predecessors. Pounded by German bombers, Britain's factories would struggle to put the device into production. But America's factories could. For months British leaders plotted to use the magnetron as a bargaining chip for American secrets in other fields. Then Winston Churchill took power and decided that desperate times called for desperate measures. Britain would simply tell the Americans what they had and ask for help. The magnetron stunned the Americans. Their research was years off the pace. President Roosevelt approved funds for a new laboratory at MIT, uniquely for the American war effort, administered not by the military but by a civilian agency. By any measure, Rad Lab was a resounding success. It spawned ten Nobel laureates. The radar it developed, detecting planes and submarines, helped to win the war. But urgency in times of war can quickly be lost in times of peace. It might have been obvious if you thought about it that civilian aviation needed radar given how quickly it was expanding. In 1945 at the war's end, US domestic airlines carried seven million passengers. By 1955 it was 38 million. And the busier the skies, the more useful radar would be at preventing collisions. But roll out was slow and patchy. Some airports installed it, many didn't. In most airspace, planes weren't tracked at all. Pilots submitted their flight plans in advance, which should in theory ensure that no two planes were going to be in the same place at the same time. But avoiding collisions ultimately came down to a four word protocol. See and be seen. On June 30th 1956, two passenger flights departed Los Angeles Airport, three minutes apart. One was bound for Kansas City, one for Chicago. Their planned flight paths intersected above the Grand Canyon, but at different heights. Then thunderclouds developed. One plane's captain radioed to ask permission to fly above the storm. The air traffic controller cleared him to go a thousand on top, a thousand feet above cloud cover. See and be seen. Nobody knows for sure what happened. Planes then had no black boxes and there were no survivors. But just before 10.31, air traffic control heard a garbled radio transmission. Pull up, pull up. We are going in.
SPEAKER_01: From the pattern of the wreckage, strewn for miles across the canyon floor, the planes seemed to have approached each other at a 25 degree angle, presumably through a cloud. Investigators speculated that both pilots were distracted by trying to find gaps in the clouds so passengers could enjoy the scenery. Accidents happen. The question is what risks we're willing to run for the economic benefits. That question is becoming pertinent again with respect to crowded skies. Many people have high hopes for unmanned aerial vehicles or drones. They're already being used for everything from movie making to crop spraying. Companies like Amazon expect the skies of our cities soon to be buzzing with grocery deliveries. Civil aviation authorities are grappling with what to approve. Drones have sense and avoid technology and it's pretty good. But is it good enough? The crash over the Grand Canyon certainly concentrated minds. If technology existed to prevent things like this, shouldn't we make more effort to use it? Within two years, what's now known as the Federal Aviation Administration was born in the United States. And today, American skies are 20 times busier still. The world's biggest airports now see planes taking off and landing at an average of nearly two a minute. Collisions are absurdly rare no matter how cloudy the conditions. That's thanks to many things, but it's largely thanks to radar.
SPEAKER_02: Robert Boudary wrote an excellent history of radar titled The Invention That Changed the World. For a full list of our sources, please see bbcworldservice.com slash 50 things.
SPEAKER_01: Hello, it's me again. The radar was the 43rd thing on my list of 50. So seven more to go. Actually, I want it to be eight. I want a 51st thing. So please tell me, what's the one extra thing you think I should be looking at? If you listen to the series regularly, you know I'm looking for the underrated, the unexpected, the overlooked. If you're listening to this before 12 noon GMT on the 8th of September 2017, and if you haven't already, please send in your suggestions. I will then choose my six favorites and in a few weeks, you'll have the chance to vote online. There'll be a special extra podcast all about the winning 51st thing. You can email me at 51, that's 51, 51things at bbc.com or you can send a message on the BBC World Service page on Facebook or let us know on Twitter at BBC World Service. Remember, the deadline for suggestions is the 8th of September 2017 at 12 noon GMT. You can see a list of all my 50 things at bbcworldservice.com slash 51things. Again, 51 is 5-1. I can't wait to see what you suggest.
