1 00:00:15,370 --> 00:00:25,890 Speaker 1: Pushkin. On the twentieth of July nineteen eighty three, Air 2 00:00:25,970 --> 00:00:29,210 Speaker 1: Canada Flight one four three was being prepared for its 3 00:00:29,290 --> 00:00:33,730 Speaker 1: two thousand mile cross country flight from Montreal to Edmonton. 4 00:00:34,890 --> 00:00:37,610 Speaker 1: The ground crew loaded her up with a necessary fuel 5 00:00:37,970 --> 00:00:42,330 Speaker 1: twenty two thousand, six hundred kilograms according to their calculations. 6 00:00:42,850 --> 00:00:47,810 Speaker 1: Those calculations were correct up to a point, but unfortunately 7 00:00:47,850 --> 00:00:51,810 Speaker 1: they're mixed up kilograms and pounds, and not in a 8 00:00:51,850 --> 00:00:55,730 Speaker 1: good way. Nobody had any idea of this, but the 9 00:00:55,770 --> 00:00:59,170 Speaker 1: plane took off for a four hour flight with only 10 00:00:59,250 --> 00:01:02,730 Speaker 1: half the fuel it needed to get to Edmonton. The 11 00:01:02,810 --> 00:01:05,210 Speaker 1: plane was now on course to run out of fuel 12 00:01:06,010 --> 00:01:11,970 Speaker 1: somewhere over Winnipeg. I'm Tim Harford and you're listening to 13 00:01:12,170 --> 00:01:37,210 Speaker 1: Cautionary Tales. This is a new experiment for us. Here 14 00:01:37,250 --> 00:01:40,930 Speaker 1: at Cautionary Tales. As usual, you'll hear a story of disaster, 15 00:01:41,090 --> 00:01:43,930 Speaker 1: but I'll be joined by an expert to help tell 16 00:01:43,970 --> 00:01:46,850 Speaker 1: the story and reflect on the lessons. I hope you 17 00:01:46,930 --> 00:01:49,290 Speaker 1: like it, and I'm confident you will, because my guest 18 00:01:49,330 --> 00:01:53,250 Speaker 1: today is Matt Parker. Matt Parker is a phenomenon, a 19 00:01:53,370 --> 00:01:57,770 Speaker 1: stand up comedian, mathematician, YouTuber, podcaster, an author of the 20 00:01:57,890 --> 00:02:02,050 Speaker 1: number one bestseller Humble Pie and Humble Pie is a funny, 21 00:02:02,290 --> 00:02:06,090 Speaker 1: nerdy book about the real life consequences of mathematical mistakes, 22 00:02:06,090 --> 00:02:08,810 Speaker 1: and it's where I first heard the story of air 23 00:02:09,650 --> 00:02:13,730 Speaker 1: flight one four three. Matt Parker, Welcome to Cautionary Sales. 24 00:02:13,850 --> 00:02:16,610 Speaker 1: Thank you, Tim. It's an absolute honor to be your 25 00:02:16,810 --> 00:02:20,850 Speaker 1: zeroth guest on the show zero both guests. Matt counts 26 00:02:20,890 --> 00:02:24,170 Speaker 1: in strange wayst this story is a bit like an onion. 27 00:02:24,170 --> 00:02:27,290 Speaker 1: It's got layers. Yeah, on the most superficial level, the 28 00:02:27,410 --> 00:02:29,970 Speaker 1: sort of papery outer layer of the story. If you like, 29 00:02:30,290 --> 00:02:32,490 Speaker 1: why did this plane have too little fuel? The very 30 00:02:32,530 --> 00:02:37,450 Speaker 1: simple reading is they had a unit conversion error. So 31 00:02:37,770 --> 00:02:39,890 Speaker 1: the people who are meant to be fueling the aircraft 32 00:02:40,330 --> 00:02:43,690 Speaker 1: saw a number, they assumed it was pounds of fuel, 33 00:02:43,930 --> 00:02:46,250 Speaker 1: when in fact it was kilograms of fuel. And the 34 00:02:46,290 --> 00:02:48,650 Speaker 1: reason they're even doing this in mass because if you 35 00:02:48,690 --> 00:02:51,090 Speaker 1: fill up a car, you don't put the fuel in 36 00:02:51,650 --> 00:02:56,410 Speaker 1: by mass, you do it by volume. Volume changes based 37 00:02:56,450 --> 00:02:59,410 Speaker 1: on the ambient temperature. As things warm up, they tend 38 00:02:59,410 --> 00:03:01,690 Speaker 1: to expand, if they cool down, they tend to shrink. 39 00:03:01,770 --> 00:03:05,130 Speaker 1: And if you're flying an aircraft, it's important you have 40 00:03:05,690 --> 00:03:08,530 Speaker 1: the amount of fuel you're supposed to have, and so 41 00:03:08,650 --> 00:03:12,250 Speaker 1: they may insure instead of using the straightforward volume, they 42 00:03:12,250 --> 00:03:16,050 Speaker 1: were going to use mass instead. And sadly it was 43 00:03:16,050 --> 00:03:20,210 Speaker 1: that attempt for extra precision that opened up the door 44 00:03:20,330 --> 00:03:22,890 Speaker 1: for this unit conversion error. Yes, you would think they 45 00:03:22,970 --> 00:03:25,250 Speaker 1: might just stick in a little bit extra just to 46 00:03:25,250 --> 00:03:27,250 Speaker 1: be sure, but there's limits to the amount of extra 47 00:03:27,250 --> 00:03:29,930 Speaker 1: fuel you want on a plane because yeah, it's heavy. Yeah, 48 00:03:30,050 --> 00:03:33,290 Speaker 1: And so they even allowed enough extra so that twenty 49 00:03:33,330 --> 00:03:37,290 Speaker 1: two six hundred kilograms you mentioned, that's twenty two thousand, 50 00:03:37,450 --> 00:03:40,690 Speaker 1: three hundred kilograms for the flying bit, and then they 51 00:03:40,730 --> 00:03:44,210 Speaker 1: put on the extra three hundred kilograms for like taxiing 52 00:03:44,210 --> 00:03:47,050 Speaker 1: and like all the bits that maybe they hadn't factored 53 00:03:47,050 --> 00:03:49,650 Speaker 1: into the flight. So they were trying to be careful, 54 00:03:49,850 --> 00:03:52,570 Speaker 1: they were being thorough, they just got the units wrong. 55 00:03:53,050 --> 00:03:55,850 Speaker 1: What it was it about Canada at this particular time 56 00:03:55,970 --> 00:03:59,090 Speaker 1: that made it particularly vulnerable to a unit conversion error. 57 00:03:59,370 --> 00:04:04,250 Speaker 1: In Canada, they had just switched so previously they were 58 00:04:04,330 --> 00:04:07,730 Speaker 1: using imperial units or like the old school, like English 59 00:04:07,970 --> 00:04:11,490 Speaker 1: style units, and they just swopped over to real units 60 00:04:11,970 --> 00:04:15,810 Speaker 1: or metric as the rest of US. I was about 61 00:04:15,850 --> 00:04:18,090 Speaker 1: to say that as in Australian you're neutral in this fight, 62 00:04:18,170 --> 00:04:21,570 Speaker 1: but you're clearly not neutral. Okay, no, no, not since 63 00:04:21,650 --> 00:04:26,330 Speaker 1: the nineteen sixties. I love the quirkiness of the imperial system. 64 00:04:26,450 --> 00:04:29,130 Speaker 1: That metric is nice and straightforward. Yeah, but if there's 65 00:04:29,170 --> 00:04:32,450 Speaker 1: one thing that's worse than using imperiod units, it's using 66 00:04:32,490 --> 00:04:35,490 Speaker 1: imperiod units when you think you're using metric units or 67 00:04:35,610 --> 00:04:39,050 Speaker 1: vice versa exactly. And it was even obscured by one 68 00:04:39,170 --> 00:04:42,410 Speaker 1: layer because when they were doing the calculations, they weren't 69 00:04:42,410 --> 00:04:46,010 Speaker 1: actually doing it in terms of the direct mass. They 70 00:04:46,010 --> 00:04:48,890 Speaker 1: were using something called the specific gravity, which is like 71 00:04:48,890 --> 00:04:51,650 Speaker 1: a measure the density of the fuel, and so they 72 00:04:51,770 --> 00:04:53,650 Speaker 1: used that to get back to the volume that they 73 00:04:53,650 --> 00:04:55,970 Speaker 1: then had to put into the plane. And because there 74 00:04:56,010 --> 00:04:59,290 Speaker 1: was this extra one layer of opaque bit of putting 75 00:04:59,290 --> 00:05:01,330 Speaker 1: it into a slightly different way of looking at it, 76 00:05:01,770 --> 00:05:04,290 Speaker 1: they didn't realize that the units behind the specific gravity 77 00:05:04,330 --> 00:05:07,170 Speaker 1: were based on kilograms and they assume that they were 78 00:05:07,170 --> 00:05:10,290 Speaker 1: based the old way on pounds. There's more maths than 79 00:05:10,330 --> 00:05:13,930 Speaker 1: I had anticipated in filling up a plane. Yeah, okay, 80 00:05:13,970 --> 00:05:16,170 Speaker 1: this is slightly unnerving, but I mean it's not just 81 00:05:16,250 --> 00:05:19,770 Speaker 1: planes that suffer from unit conversion. Eras your book Humble 82 00:05:19,810 --> 00:05:22,290 Speaker 1: Pie has a whole chapter full of them. I mean, 83 00:05:22,290 --> 00:05:24,530 Speaker 1: do you have any favorites with This? Plane is now 84 00:05:24,570 --> 00:05:27,090 Speaker 1: my favorite? You said you only came across it because 85 00:05:27,090 --> 00:05:29,290 Speaker 1: you were reading the book. I only came across a 86 00:05:29,450 --> 00:05:33,410 Speaker 1: researching the book. Prior to that. It was the Mars 87 00:05:33,530 --> 00:05:37,570 Speaker 1: Climate Orbiter spacecraft that NASA launched in nineteen ninety eight. 88 00:05:37,810 --> 00:05:41,210 Speaker 1: That was my favorite unit conversion era. And that's partly 89 00:05:41,210 --> 00:05:43,570 Speaker 1: because a lot of people know about it. There's this 90 00:05:43,730 --> 00:05:47,210 Speaker 1: urban legend of when NASA got the maths wrong, and 91 00:05:47,290 --> 00:05:51,290 Speaker 1: partly this is something very delightful about NASA, like the 92 00:05:51,330 --> 00:05:55,730 Speaker 1: mascot of science and precision and achievement coming undone because 93 00:05:55,770 --> 00:05:57,970 Speaker 1: of a unit conversion era. It was actually a bit 94 00:05:58,010 --> 00:05:59,930 Speaker 1: more subtle than that, wasn't it. I think NASA we're 95 00:06:00,050 --> 00:06:03,010 Speaker 1: using metric, but the sply was using imperial or old 96 00:06:03,010 --> 00:06:06,970 Speaker 1: school pounds. Yeah, it was Lockeed Martin was the contractor. 97 00:06:07,210 --> 00:06:10,570 Speaker 1: And like you said, NASA use metric. They're scientists, they're engineers. 98 00:06:10,610 --> 00:06:13,690 Speaker 1: They're going to use the most efficient, most optimal units, 99 00:06:13,690 --> 00:06:15,890 Speaker 1: and so everything they were doing was in metric and 100 00:06:16,050 --> 00:06:19,290 Speaker 1: in their documentation that they gave to their contractors, it's 101 00:06:19,330 --> 00:06:23,130 Speaker 1: stipulated you're going to do this in metric. Now, the 102 00:06:23,250 --> 00:06:26,810 Speaker 1: kind of common understanding of this is when the Mars 103 00:06:26,850 --> 00:06:30,690 Speaker 1: Climate orbiter got to Mars, they had to calculate how 104 00:06:30,730 --> 00:06:32,770 Speaker 1: far above the surface it was so they could put 105 00:06:32,810 --> 00:06:36,010 Speaker 1: it into a nice, neat stable orbit and people go, oh, 106 00:06:36,050 --> 00:06:39,890 Speaker 1: isn't that the one where NASA thought it was in 107 00:06:40,010 --> 00:06:42,210 Speaker 1: feet but it was actually a meters or vice versa, 108 00:06:42,250 --> 00:06:44,690 Speaker 1: And then they got the altitude wrong because they were 109 00:06:44,690 --> 00:06:48,930 Speaker 1: measuring the distance incorrectly. And to be fair to this day, 110 00:06:49,090 --> 00:06:51,490 Speaker 1: if you look at altitude of things like aircraft, it's 111 00:06:51,490 --> 00:06:54,650 Speaker 1: given in feet, which in one sense is a nice 112 00:06:54,770 --> 00:06:59,010 Speaker 1: bit of error correction, because if you hear a number 113 00:06:59,130 --> 00:07:02,090 Speaker 1: in aviation and its feet, you know it's in the 114 00:07:02,210 --> 00:07:05,010 Speaker 1: vertical direction, and if you hear a number and it's 115 00:07:05,170 --> 00:07:08,970 Speaker 1: kilometers or meters, you know it's in the horizontal direction. 116 00:07:09,490 --> 00:07:12,130 Speaker 1: And so it's a bit of redundancy in terms of 117 00:07:12,130 --> 00:07:15,690 Speaker 1: the directions encoded in the units that are used. Which 118 00:07:16,130 --> 00:07:18,490 Speaker 1: is maybe the one time I will concede that's an 119 00:07:18,490 --> 00:07:21,970 Speaker 1: interesting use for imperial units, but that's not the case. Here. 120 00:07:22,050 --> 00:07:24,490 Speaker 1: First time I've ever heard you defend values, I know 121 00:07:24,850 --> 00:07:27,650 Speaker 1: I know where defend is a strong word tim but 122 00:07:27,730 --> 00:07:29,970 Speaker 1: actually that's not what NASA did. They didn't confuse feet 123 00:07:30,010 --> 00:07:32,090 Speaker 1: and meters and kind of just smash this thing into 124 00:07:32,090 --> 00:07:33,770 Speaker 1: the surface of mask because they didn't know how high 125 00:07:33,770 --> 00:07:35,730 Speaker 1: it was. It is a much more soft lever. It's 126 00:07:35,770 --> 00:07:38,330 Speaker 1: always more complicated than that. In this case, as they're 127 00:07:38,370 --> 00:07:40,890 Speaker 1: flying the spacecraft from the Earth to Mars, there's a 128 00:07:40,930 --> 00:07:43,930 Speaker 1: big flywheel on board, because in space, there's nothing to 129 00:07:43,970 --> 00:07:46,290 Speaker 1: push against if you want to change your direction. But 130 00:07:46,330 --> 00:07:49,170 Speaker 1: if you have a spinning mass, you get the gyroscopic 131 00:07:49,210 --> 00:07:52,770 Speaker 1: effect and you can push against something spinning to reorientate 132 00:07:52,770 --> 00:07:56,730 Speaker 1: your spacecraft. The issue with that is sometimes your flywheel 133 00:07:56,970 --> 00:08:00,090 Speaker 1: is going incredibly fast and you have to have what 134 00:08:00,130 --> 00:08:05,490 Speaker 1: the NASA scientists have deemed a angular momentum desaturation event, 135 00:08:05,810 --> 00:08:08,770 Speaker 1: which is just slowing down the flywheel. But to do that, 136 00:08:09,090 --> 00:08:11,970 Speaker 1: you've got to fire the thrusters, like the little steering 137 00:08:12,050 --> 00:08:15,370 Speaker 1: rockets on the spacecraft to keep it pointing in roughly 138 00:08:15,410 --> 00:08:18,850 Speaker 1: the same direction as you're slowing down your gyroscope, and 139 00:08:18,970 --> 00:08:24,170 Speaker 1: those little thruster firings slightly change the trajectory of the 140 00:08:24,210 --> 00:08:26,570 Speaker 1: spacecraft on its way to Mars. So you want to 141 00:08:26,650 --> 00:08:29,770 Speaker 1: keep track of those. This was an external system done 142 00:08:29,810 --> 00:08:32,490 Speaker 1: by lockeed Mutton, and they've got a little program that 143 00:08:32,690 --> 00:08:35,650 Speaker 1: just logged every single time the thrusters fired how much 144 00:08:35,690 --> 00:08:39,810 Speaker 1: force they were firing, and therefore, later on NASA could 145 00:08:39,810 --> 00:08:43,490 Speaker 1: calculate the actual trajectory when it gets to Mars by 146 00:08:43,530 --> 00:08:46,770 Speaker 1: factoring in all these little thruster firings. And NASA said, 147 00:08:47,290 --> 00:08:52,250 Speaker 1: very very clearly, please write these down using mutants the 148 00:08:52,410 --> 00:08:56,850 Speaker 1: proper metric unit for force, and lockeed Martin wrote them 149 00:08:56,890 --> 00:09:00,970 Speaker 1: down as pounds force, pounds force. It's a ratio of 150 00:09:01,010 --> 00:09:05,730 Speaker 1: four point four five ish, very similar. It's pounds pounds 151 00:09:05,730 --> 00:09:08,090 Speaker 1: are killers all over again. Really, and this is the 152 00:09:08,170 --> 00:09:10,970 Speaker 1: kind of thing little smash your spacecraft straight into Mars. 153 00:09:11,170 --> 00:09:14,970 Speaker 1: Oh yeah. Because they assumed that the firings were in 154 00:09:15,170 --> 00:09:17,530 Speaker 1: Newton's when they've been written down in pounds fource, they 155 00:09:17,610 --> 00:09:19,650 Speaker 1: figured they were going to come in at an altitude 156 00:09:19,650 --> 00:09:21,450 Speaker 1: of between one hundred and fifty and one hundred and 157 00:09:21,490 --> 00:09:24,570 Speaker 1: seventy kilometers above the surface of Mars. They actually came 158 00:09:24,610 --> 00:09:28,050 Speaker 1: in at fifty seven kilometers above the surface of Mars, 159 00:09:28,210 --> 00:09:30,850 Speaker 1: much much closer, which means even though there's not a 160 00:09:30,850 --> 00:09:33,610 Speaker 1: lot of atmosphere on Mars, there is some The extra 161 00:09:33,690 --> 00:09:36,730 Speaker 1: drag of being that much lower slowed the spacecraft down 162 00:09:36,850 --> 00:09:39,850 Speaker 1: a lot more than they expected, which meant that it 163 00:09:39,970 --> 00:09:43,370 Speaker 1: fell out of the sky. It deorbited very ungracefully, and 164 00:09:44,050 --> 00:09:47,890 Speaker 1: billions of US dollars a spacecraft slammed into the surface 165 00:09:47,890 --> 00:09:51,090 Speaker 1: of Mars because of one unit conversion error. I wanted 166 00:09:51,090 --> 00:09:54,450 Speaker 1: to ask about a really old conversion error, which pleasingly 167 00:09:54,530 --> 00:09:57,370 Speaker 1: rhymes with NASA. So it was Vasa Vassa is this ship? 168 00:09:57,450 --> 00:10:01,170 Speaker 1: What's the story with there? This was a ship in 169 00:10:01,250 --> 00:10:05,210 Speaker 1: Sweden that was launched in the sixteen hundreds, in the 170 00:10:05,290 --> 00:10:09,050 Speaker 1: year sixteen twenty eight, and it was a magnificent, massive ship. 171 00:10:09,290 --> 00:10:11,130 Speaker 1: They put a lot of cannons on the top of it, 172 00:10:11,290 --> 00:10:13,490 Speaker 1: which might have been part of the problem because almost 173 00:10:13,530 --> 00:10:18,250 Speaker 1: immediately in its maiden voyage it toppled over. At the 174 00:10:18,290 --> 00:10:20,610 Speaker 1: time they're like, it was top heavy. We put too 175 00:10:20,650 --> 00:10:22,770 Speaker 1: many cans on the top. The ship was too tall, 176 00:10:22,850 --> 00:10:25,130 Speaker 1: and that caused it almost as soon as it left 177 00:10:25,130 --> 00:10:28,050 Speaker 1: the harbor, just just fall over on its side and sink. 178 00:10:28,170 --> 00:10:31,530 Speaker 1: And it wasn't actually found until the nineteen fifties. And 179 00:10:31,610 --> 00:10:34,850 Speaker 1: in nineteen sixty one they dredged it up and they 180 00:10:34,890 --> 00:10:37,330 Speaker 1: put it in a museum, which if you're ever in Stockholm, 181 00:10:37,370 --> 00:10:39,770 Speaker 1: I highly recommend you good at the Vassa Museum. The 182 00:10:39,810 --> 00:10:43,850 Speaker 1: ship was incredibly well preserved, so well preserved that some 183 00:10:43,890 --> 00:10:46,210 Speaker 1: people have a good look at it and thought that 184 00:10:46,370 --> 00:10:50,250 Speaker 1: looks a little asymmetric, Like the hole is not as 185 00:10:50,290 --> 00:10:53,530 Speaker 1: symmetric as you would hope a hole would be on 186 00:10:53,610 --> 00:10:56,170 Speaker 1: a ship. I mean that is a property I tend 187 00:10:56,170 --> 00:10:59,930 Speaker 1: to associate with ships exactly. Everyone likes a good symmetric 188 00:10:59,970 --> 00:11:03,610 Speaker 1: ships as a rule of thumb. So people looked at 189 00:11:03,610 --> 00:11:05,130 Speaker 1: it and went, dan, it's not as symmetric as it 190 00:11:05,170 --> 00:11:08,170 Speaker 1: should be, as other theory now is. When it was built, 191 00:11:08,410 --> 00:11:13,850 Speaker 1: it was built lightly asymmetrically because people were using different units. Specifically, 192 00:11:13,890 --> 00:11:19,010 Speaker 1: people were mixing up Swedish feet with the Amsterdam feet. 193 00:11:19,090 --> 00:11:22,250 Speaker 1: And we know this because we've found in all the 194 00:11:22,290 --> 00:11:25,970 Speaker 1: other bits of paraphernalia that came with the ship rulers 195 00:11:26,010 --> 00:11:29,010 Speaker 1: that we assume we're used when building the ship, and 196 00:11:29,090 --> 00:11:34,330 Speaker 1: they found both Swedish feet rulers and Amsterdam feet rulers, 197 00:11:34,330 --> 00:11:37,850 Speaker 1: which are different lengths, so a foot in Amsterdam is 198 00:11:37,890 --> 00:11:41,210 Speaker 1: different to a foot in Sweden. They've even got different 199 00:11:41,250 --> 00:11:44,810 Speaker 1: numbers of inches. A Swedish foot is divided up into 200 00:11:44,850 --> 00:11:48,130 Speaker 1: twelve inches and an Amsterdam foot divided up into eleven inches, 201 00:11:48,170 --> 00:11:49,930 Speaker 1: and of course the inches are then different. So the 202 00:11:49,930 --> 00:11:52,570 Speaker 1: theory now is when their ship was built in the 203 00:11:52,610 --> 00:11:54,770 Speaker 1: sixteen hundreds and people are like, oh, make it to 204 00:11:54,770 --> 00:11:57,410 Speaker 1: this many inches, this many feet. People are using different 205 00:11:57,490 --> 00:12:01,730 Speaker 1: rulers that are different lengths divided into different numbers of subdivisions, 206 00:12:01,770 --> 00:12:04,450 Speaker 1: and they've got some bits off, and so the ship 207 00:12:04,610 --> 00:12:07,530 Speaker 1: ended up a little bit wonky, sadly for them, and 208 00:12:07,770 --> 00:12:11,170 Speaker 1: great for us because it preserved this incredible warship. It 209 00:12:11,290 --> 00:12:13,970 Speaker 1: toppled over almost as soon as it sets sail. So 210 00:12:14,050 --> 00:12:17,690 Speaker 1: let's get back to Air Canada Flight one four three. 211 00:12:17,730 --> 00:12:20,370 Speaker 1: I flipped over the page in your book, and almost 212 00:12:20,370 --> 00:12:23,330 Speaker 1: the first thing that happens is it lands in Ottawa. 213 00:12:23,530 --> 00:12:26,170 Speaker 1: For some reason, they did this before they embarked on 214 00:12:26,210 --> 00:12:29,290 Speaker 1: the real journey, which is two thousand miles, and so 215 00:12:29,330 --> 00:12:31,370 Speaker 1: I thought, oh, it's a fake ount. Matt has faked 216 00:12:31,370 --> 00:12:34,250 Speaker 1: me out. They landed Ottawa, they checked the fuel, they 217 00:12:34,290 --> 00:12:37,650 Speaker 1: figure out there's been a near miss, nearly fatal error, 218 00:12:37,890 --> 00:12:40,130 Speaker 1: and they top it up and it's all fine. Not 219 00:12:40,330 --> 00:12:44,730 Speaker 1: quite so. There are layers and layers of mistakes that 220 00:12:44,770 --> 00:12:48,410 Speaker 1: were occurring, and it was a series of very unfortunate 221 00:12:48,450 --> 00:12:50,930 Speaker 1: mistakes which caused the plane to take off with the 222 00:12:50,970 --> 00:12:53,930 Speaker 1: wrong amount of fuel. But then a stroke of good luck, 223 00:12:54,090 --> 00:12:56,930 Speaker 1: they had to land early because they were changing passages 224 00:12:57,450 --> 00:13:00,770 Speaker 1: in Ottawa, and whenever you land, you have to redo 225 00:13:00,850 --> 00:13:05,170 Speaker 1: the fuel calculations. But as people may have realized based 226 00:13:05,210 --> 00:13:07,850 Speaker 1: on the percentage through this podcast, we are at the moment, 227 00:13:07,890 --> 00:13:10,130 Speaker 1: that's not the end of the story. They redid the 228 00:13:10,170 --> 00:13:15,410 Speaker 1: calculations and made exactly the same unit conversion error. They 229 00:13:15,530 --> 00:13:19,490 Speaker 1: once again did the calculations based on pounds instead of 230 00:13:19,490 --> 00:13:22,090 Speaker 1: doing it based on kilograms, and they're like, yep, that 231 00:13:22,250 --> 00:13:24,850 Speaker 1: checks out. That's the exact amount of fuel we need. 232 00:13:25,130 --> 00:13:28,290 Speaker 1: We will carry on with no additional fuel. Well done. 233 00:13:28,490 --> 00:13:31,650 Speaker 1: Whoever fueled this plane in the first place. So there 234 00:13:31,650 --> 00:13:35,090 Speaker 1: we are. Air Canada Flight one four three has taken 235 00:13:35,090 --> 00:13:39,130 Speaker 1: off not once but twice with the wrong amount of fuel, 236 00:13:39,370 --> 00:13:44,290 Speaker 1: with the calculations all messed up, and facing imminently the 237 00:13:44,330 --> 00:13:46,770 Speaker 1: fate of running out of fuel over the middle of Canada. 238 00:13:46,890 --> 00:13:50,210 Speaker 1: And after these messages that Parker and I will explain 239 00:13:50,250 --> 00:14:11,370 Speaker 1: what happened next. So we've been following Air Canada flight 240 00:14:11,610 --> 00:14:15,370 Speaker 1: on four three. It's taken off from Montreal. It has 241 00:14:15,490 --> 00:14:17,970 Speaker 1: pounds of fuel instead of kilograms of fuel. That is 242 00:14:18,050 --> 00:14:22,050 Speaker 1: not remotely enough fuel. It then has a second chance 243 00:14:22,130 --> 00:14:24,170 Speaker 1: to fix this because it lands after a short hop 244 00:14:24,250 --> 00:14:26,890 Speaker 1: land in Ottawa. They do the same calculation, They make 245 00:14:26,930 --> 00:14:29,210 Speaker 1: the same mistake. They say, Yep, there's plenty of fuel 246 00:14:29,250 --> 00:14:32,290 Speaker 1: in there. Because they're confusing pounds and kilograms. There is 247 00:14:32,290 --> 00:14:34,330 Speaker 1: not plenty of fuel in there. And the plane takes 248 00:14:34,370 --> 00:14:36,370 Speaker 1: off again, and now it's really in trouble because now 249 00:14:36,370 --> 00:14:38,650 Speaker 1: it is going to fly two thousand miles. People listening 250 00:14:38,650 --> 00:14:41,250 Speaker 1: to this will be screaming, why didn't they check the 251 00:14:41,290 --> 00:14:43,530 Speaker 1: fuel gauge? Does a plane not have a fuel gauge? 252 00:14:43,570 --> 00:14:45,610 Speaker 1: My car has a fuel gage, surely a plane has 253 00:14:45,610 --> 00:14:47,450 Speaker 1: a fuel gage. So what's going on with the fuel gage? 254 00:14:47,490 --> 00:14:49,770 Speaker 1: I mean a plane does have a fuel gage. In fact, 255 00:14:50,010 --> 00:14:52,810 Speaker 1: it's kind of got a double fuel gauge. Because redundancy 256 00:14:53,330 --> 00:14:57,370 Speaker 1: is the motto of aviation, because you know something goes wrong, 257 00:14:57,410 --> 00:15:01,050 Speaker 1: it goes very wrong. And so they had a gauge 258 00:15:01,330 --> 00:15:03,650 Speaker 1: that shows the fuel and they've got like a unit 259 00:15:03,690 --> 00:15:06,450 Speaker 1: that then does the calculations to work out how much fuel, 260 00:15:06,530 --> 00:15:08,890 Speaker 1: and they've got sensors in the fuel tanks that are 261 00:15:09,090 --> 00:15:11,450 Speaker 1: measuring how much fuel, and they're all joined together to 262 00:15:11,570 --> 00:15:14,170 Speaker 1: give you extra redundancy. There's more than one sensor in 263 00:15:14,210 --> 00:15:16,250 Speaker 1: the tank, there's more than one link between the sensors 264 00:15:16,370 --> 00:15:18,410 Speaker 1: and the unit. There's the calculation, and then you've got 265 00:15:18,490 --> 00:15:21,930 Speaker 1: the display on the gauge. And one flight prior to 266 00:15:21,970 --> 00:15:25,130 Speaker 1: this flight. So when the plane was actually in Edmonton 267 00:15:25,290 --> 00:15:28,610 Speaker 1: ready to come over to Montreal to start this fateful flight, 268 00:15:28,810 --> 00:15:31,330 Speaker 1: they realized there was an issue with the senses because 269 00:15:31,330 --> 00:15:35,130 Speaker 1: the gauge had stopped working. And a technician realized, if 270 00:15:35,170 --> 00:15:39,170 Speaker 1: you unplug just one of the connections, if you remove 271 00:15:39,290 --> 00:15:43,530 Speaker 1: that layer of redundancy, there starts working again. And they're like, oh, 272 00:15:43,530 --> 00:15:46,450 Speaker 1: that's interesting, and in theory that should be fine because 273 00:15:46,490 --> 00:15:49,090 Speaker 1: they just label their right, I've removed this because it 274 00:15:49,130 --> 00:15:51,690 Speaker 1: wasn't working. You now have to do a manual check 275 00:15:51,890 --> 00:15:54,170 Speaker 1: as your layer of redundancy. Because we've removed it from 276 00:15:54,170 --> 00:15:56,370 Speaker 1: the sensors, You've now got to do it manually. But 277 00:15:56,450 --> 00:15:58,730 Speaker 1: this is where the chain of mistakes, the layers of 278 00:15:58,770 --> 00:16:02,170 Speaker 1: this onion really kick off, because there was just one 279 00:16:02,250 --> 00:16:06,050 Speaker 1: thing after another that went wrong, so that technician poorly 280 00:16:06,170 --> 00:16:09,250 Speaker 1: labeled what they had done. They just wrote faulty or 281 00:16:09,250 --> 00:16:11,650 Speaker 1: something to that effect. They then didn't write it very 282 00:16:11,690 --> 00:16:14,090 Speaker 1: clearly in the log book. They then didn't explain it 283 00:16:14,170 --> 00:16:16,850 Speaker 1: very well to the pilot. The pilot understood it as 284 00:16:16,850 --> 00:16:19,370 Speaker 1: being an ongoing problem, and it was always the case 285 00:16:19,410 --> 00:16:21,170 Speaker 1: that you had to do the manual fuel check, which 286 00:16:21,170 --> 00:16:23,490 Speaker 1: is like literally putting a stick in the tank to 287 00:16:23,490 --> 00:16:25,530 Speaker 1: see how much fuel there is when they finished the 288 00:16:25,570 --> 00:16:29,290 Speaker 1: next flight. The pilot then badly communicated this to the 289 00:16:29,290 --> 00:16:32,970 Speaker 1: next pilot, and the technician handover was equally bad. Like 290 00:16:33,050 --> 00:16:35,410 Speaker 1: at any point someone could have realized what was going on, 291 00:16:35,650 --> 00:16:38,690 Speaker 1: but the communication didn't work, and so the new pilot 292 00:16:39,090 --> 00:16:41,610 Speaker 1: was told, don't panic. As long as you do the 293 00:16:41,610 --> 00:16:45,050 Speaker 1: manual check, it's fine. Separately, a different technician's popped in, 294 00:16:45,370 --> 00:16:49,490 Speaker 1: realized it's unconnected, connected it back in again, rediscovered the 295 00:16:49,530 --> 00:16:52,570 Speaker 1: same issue the previous technician had left it plugged in, 296 00:16:52,810 --> 00:16:55,970 Speaker 1: went off to order the new part. The new pilot 297 00:16:56,250 --> 00:16:59,530 Speaker 1: sees the old label, which is now irrelevant, saying faulty, 298 00:16:59,850 --> 00:17:01,770 Speaker 1: but it's plugged back in again, which means none of 299 00:17:01,770 --> 00:17:04,890 Speaker 1: the gauges are working. All of this just comes together 300 00:17:05,290 --> 00:17:07,770 Speaker 1: as the pilot is sitting there looking at this label, 301 00:17:08,130 --> 00:17:10,690 Speaker 1: looking at the blank game age, and everything they've been 302 00:17:10,730 --> 00:17:14,050 Speaker 1: told just happens to line up, and they think, oh, 303 00:17:14,090 --> 00:17:16,370 Speaker 1: it's fine, as long as we do the manual check, 304 00:17:16,730 --> 00:17:20,130 Speaker 1: we can still fly even though the gauge is completely dead, 305 00:17:20,370 --> 00:17:23,690 Speaker 1: without realizing it is very much not what they should 306 00:17:23,730 --> 00:17:26,690 Speaker 1: be doing. So I did once run out of fuel, 307 00:17:27,170 --> 00:17:29,690 Speaker 1: and I fortunately I was on the ground in a car, 308 00:17:29,770 --> 00:17:32,210 Speaker 1: but I ran out of fuel because there'd been a 309 00:17:32,250 --> 00:17:36,130 Speaker 1: problem with the pump. The pump kept clicking out as 310 00:17:36,130 --> 00:17:39,490 Speaker 1: I was refueling in a way that indicated that the 311 00:17:39,530 --> 00:17:42,450 Speaker 1: tank was full. Yeah, but the fuel gage was showing 312 00:17:42,450 --> 00:17:45,410 Speaker 1: that the tank was nearly empty, and I just assumed 313 00:17:45,450 --> 00:17:48,250 Speaker 1: that the pump was correct and the fuel gage was wrong. 314 00:17:48,290 --> 00:17:50,170 Speaker 1: So I thought, huh, I got a broken fuel gage, 315 00:17:50,450 --> 00:17:55,050 Speaker 1: and off I drove, and I was not full. But yeah, 316 00:17:55,050 --> 00:17:57,290 Speaker 1: as I say, fortunately I was on the ground. You're 317 00:17:57,290 --> 00:18:01,530 Speaker 1: on the ground, but imagine all that happens, and you're like, huh, 318 00:18:01,570 --> 00:18:03,330 Speaker 1: you know what, I'll just get someone at the fuel 319 00:18:03,330 --> 00:18:04,930 Speaker 1: station to double check for me, and they put a 320 00:18:04,930 --> 00:18:07,130 Speaker 1: stick in your fuel tank. They do the calculation they're like, 321 00:18:07,130 --> 00:18:08,850 Speaker 1: oh no, no no, no, no, You've got loads of fuel, 322 00:18:09,130 --> 00:18:12,010 Speaker 1: but they've made a unit conversion error, and that parallel 323 00:18:12,050 --> 00:18:17,090 Speaker 1: mistake has reinforced your series of mistakes and misunderstandings, and 324 00:18:17,130 --> 00:18:19,650 Speaker 1: then you drive off without enough fuel. And there's actually 325 00:18:19,850 --> 00:18:25,890 Speaker 1: a theory in accident well, I guess mistake mitigation called 326 00:18:25,930 --> 00:18:30,970 Speaker 1: the Swiss cheese principle of avoiding disasters. Will you imagine 327 00:18:31,010 --> 00:18:35,330 Speaker 1: each check, each bit of redundancy, each failsafe as being 328 00:18:35,410 --> 00:18:38,650 Speaker 1: like a barrier to stop mistakes from getting through. But 329 00:18:38,770 --> 00:18:41,450 Speaker 1: no barrier is perfect. Some of them are operated by 330 00:18:41,530 --> 00:18:44,410 Speaker 1: humans and we can make mistakes. Some of them are 331 00:18:44,450 --> 00:18:46,770 Speaker 1: run by code on machines and they make mistakes. And 332 00:18:46,810 --> 00:18:49,050 Speaker 1: so each barrier has a few holes in it, like 333 00:18:49,090 --> 00:18:52,130 Speaker 1: a slice of Swiss cheese. But you just hope that 334 00:18:52,170 --> 00:18:54,730 Speaker 1: if you've got enough slices of cheese, one of them 335 00:18:54,810 --> 00:18:57,290 Speaker 1: will stop the mistake from getting through. But every now 336 00:18:57,290 --> 00:18:59,930 Speaker 1: and then your cheese holes just line up, and a 337 00:18:59,970 --> 00:19:03,370 Speaker 1: mistake will make it through every single layer, every single barrier, 338 00:19:03,370 --> 00:19:05,610 Speaker 1: every single failsafe, and will make it out the fast 339 00:19:05,650 --> 00:19:08,570 Speaker 1: side and become a disaster. And that's what happened with 340 00:19:08,610 --> 00:19:12,450 Speaker 1: Flight one for three. Just slice of cheese after slice 341 00:19:12,450 --> 00:19:15,130 Speaker 1: of cheese had a hole in the wrong spot and 342 00:19:15,170 --> 00:19:18,410 Speaker 1: the mistake made it through undetected, and so the plane 343 00:19:18,450 --> 00:19:22,330 Speaker 1: runs out of fuel somewhere over Winnipeg. It can't have 344 00:19:22,330 --> 00:19:24,410 Speaker 1: been a happy moment for the pilots. It was a 345 00:19:24,450 --> 00:19:27,810 Speaker 1: startling moment. I mean, the first indication they had that 346 00:19:27,850 --> 00:19:30,850 Speaker 1: something was up was a aero noise in the cockpit 347 00:19:31,370 --> 00:19:32,890 Speaker 1: that no one had heard before. They had to look 348 00:19:32,930 --> 00:19:34,650 Speaker 1: it up in the manual to see what was going on, 349 00:19:34,730 --> 00:19:37,450 Speaker 1: like this came out of nowhere, as only they realize 350 00:19:37,610 --> 00:19:39,930 Speaker 1: they're out of fuel. And this plane was one of 351 00:19:39,930 --> 00:19:43,210 Speaker 1: the first aircraft that Air Canada had brought on which 352 00:19:43,330 --> 00:19:46,210 Speaker 1: used avionics, and so there's a lot more electronics than 353 00:19:46,250 --> 00:19:49,330 Speaker 1: normal and suddenly all of it goes dead. The engines 354 00:19:49,370 --> 00:19:52,530 Speaker 1: are out, and that they're coasting. They're coasting a Boeing 355 00:19:52,810 --> 00:19:55,490 Speaker 1: seven to six seven. There were still some very basic, 356 00:19:55,810 --> 00:19:58,650 Speaker 1: rudimentary controls for the aircraft, so they were able to 357 00:19:58,690 --> 00:20:01,810 Speaker 1: glide it to some extent. And the reason why this 358 00:20:01,850 --> 00:20:05,010 Speaker 1: isn't a tale of absolute disaster, the reason why there 359 00:20:05,090 --> 00:20:08,490 Speaker 1: is a sufficiently happy ending is the pilot, before they 360 00:20:08,490 --> 00:20:11,930 Speaker 1: became like an airliner pilot for Air Canada. In their 361 00:20:11,970 --> 00:20:15,290 Speaker 1: previous career, they were a glider pilot, so the pilot 362 00:20:15,890 --> 00:20:21,130 Speaker 1: had sufficient gliding experience and they were able to glide 363 00:20:21,370 --> 00:20:25,730 Speaker 1: this bowing seven to six seven to a disused military 364 00:20:25,930 --> 00:20:28,570 Speaker 1: runway in a very small town called Gimli, and they 365 00:20:28,570 --> 00:20:31,770 Speaker 1: were able to glide this aircraft just over forty miles 366 00:20:32,170 --> 00:20:36,650 Speaker 1: and safely. Safely. It was abrupt. It's not actually a glider, 367 00:20:36,730 --> 00:20:39,410 Speaker 1: is it. It's not built to do this. No, No, 368 00:20:39,490 --> 00:20:41,970 Speaker 1: it's still going to land hard. And they couldn't bring 369 00:20:42,050 --> 00:20:44,330 Speaker 1: up like the landing gear and all this. Like they 370 00:20:44,370 --> 00:20:46,850 Speaker 1: had so few controls. They basically went straight into the 371 00:20:46,890 --> 00:20:49,450 Speaker 1: tarmac and they just like the nose went into it 372 00:20:49,450 --> 00:20:52,090 Speaker 1: and they just slid along. I guess, sparks going everywhere, 373 00:20:52,130 --> 00:20:55,370 Speaker 1: but there was just enough friction to bring the aircraft 374 00:20:55,410 --> 00:20:57,570 Speaker 1: to a halt before the fire end of the runway, 375 00:20:58,090 --> 00:21:01,130 Speaker 1: much to the relief of the sixty one passengers and 376 00:21:01,250 --> 00:21:04,010 Speaker 1: eight crew members on board, and not to the surprise 377 00:21:04,410 --> 00:21:08,490 Speaker 1: of the people currently using the airfield, and much the 378 00:21:09,330 --> 00:21:11,930 Speaker 1: big surprise to the people who were camping at the 379 00:21:11,970 --> 00:21:14,210 Speaker 1: other end of the runway. So there were people there. 380 00:21:14,370 --> 00:21:16,770 Speaker 1: They were on a go karting weekend and I guess 381 00:21:16,770 --> 00:21:19,930 Speaker 1: they booked the runway to drive go carts around. And 382 00:21:19,970 --> 00:21:22,450 Speaker 1: the crazy thing about a Boeing seven to six seven, 383 00:21:22,490 --> 00:21:25,650 Speaker 1: which the engines are turned off. It's pretty quiet, and 384 00:21:25,730 --> 00:21:28,450 Speaker 1: so they had no idea what was happening until they 385 00:21:28,650 --> 00:21:31,770 Speaker 1: hear this almighty wham and they all look around. There's 386 00:21:31,770 --> 00:21:35,850 Speaker 1: a jumbo yet sliding up this they were told disused 387 00:21:35,930 --> 00:21:39,850 Speaker 1: runway towards them, stopping just before it got to the 388 00:21:39,890 --> 00:21:42,570 Speaker 1: go cuts. So I mean, oh my goodness, once again, 389 00:21:42,690 --> 00:21:45,210 Speaker 1: things could have gone very wrong. But the last second, 390 00:21:45,370 --> 00:21:48,290 Speaker 1: thank goodness, everyone was okay. No one there. There was 391 00:21:48,330 --> 00:21:50,770 Speaker 1: no loss of life in the entire situation. It was 392 00:21:50,890 --> 00:21:53,810 Speaker 1: just amazing. I imagine a few people lost, a few hairs, 393 00:21:53,930 --> 00:21:56,570 Speaker 1: things were lost. Yeah, there's a note in your book 394 00:21:56,570 --> 00:22:01,010 Speaker 1: that they recreated this scenario in a simulator for other 395 00:22:01,050 --> 00:22:03,690 Speaker 1: pilots and it did not always go well. No, so 396 00:22:03,810 --> 00:22:06,490 Speaker 1: they obviously there's a big investigation afterwards to work out 397 00:22:06,690 --> 00:22:09,610 Speaker 1: what went wrong and how and why. And when I 398 00:22:09,650 --> 00:22:11,250 Speaker 1: was writing A Humble Pie, a lot of my time 399 00:22:11,330 --> 00:22:15,250 Speaker 1: was spent reading through these old investigations because if they 400 00:22:15,290 --> 00:22:17,770 Speaker 1: make it public to an extent, and so in there 401 00:22:17,810 --> 00:22:20,730 Speaker 1: they talked about the fact that they got other pilots 402 00:22:20,970 --> 00:22:24,690 Speaker 1: and put them in flight simulators in the same situation 403 00:22:25,210 --> 00:22:28,450 Speaker 1: to see what would happen, and every time they crashed, 404 00:22:28,890 --> 00:22:31,650 Speaker 1: no other pilot was in a stimulator was able to 405 00:22:31,690 --> 00:22:35,650 Speaker 1: glide a powerless seven six seven that distance and land 406 00:22:35,690 --> 00:22:39,370 Speaker 1: it safely. So they were very lucky that they had 407 00:22:39,370 --> 00:22:41,650 Speaker 1: the pilot they did, with the experience the pilot had 408 00:22:41,690 --> 00:22:43,930 Speaker 1: and was able to land this plane safely. It was 409 00:22:44,130 --> 00:22:46,730 Speaker 1: I mean, it very easily could have gone a different way. Yeah. 410 00:22:46,970 --> 00:22:49,450 Speaker 1: One of the other unit conversion eras in your book 411 00:22:49,690 --> 00:22:54,650 Speaker 1: is celsius fahrenheit thing on a BBC news story and 412 00:22:54,690 --> 00:22:57,970 Speaker 1: they were trying to figure out what some scientists or 413 00:22:58,010 --> 00:23:01,090 Speaker 1: somebody had basically said that there might be the following 414 00:23:01,090 --> 00:23:03,690 Speaker 1: temperature change because a climate change, and here it is 415 00:23:03,730 --> 00:23:06,970 Speaker 1: in celsius or centigrade, here it is in fahrenheit. And 416 00:23:07,050 --> 00:23:10,130 Speaker 1: the BBC just kept jumping backwards in four with really 417 00:23:10,250 --> 00:23:13,290 Speaker 1: very radical different answers to this question of how to 418 00:23:13,330 --> 00:23:16,410 Speaker 1: convert between celsius and fahrenheit. They kept changing their mind. 419 00:23:16,490 --> 00:23:19,450 Speaker 1: People just couldn't settle on the right answer. Yeah. Thankfully 420 00:23:19,490 --> 00:23:23,290 Speaker 1: people log changes to news sites so we can watch 421 00:23:23,530 --> 00:23:26,050 Speaker 1: as it went backwards and forwards, and then you're right, 422 00:23:26,050 --> 00:23:28,090 Speaker 1: there must have been a shouting match. There must have 423 00:23:28,090 --> 00:23:33,010 Speaker 1: been team three point six degrees and team thirty six degrees, 424 00:23:33,290 --> 00:23:36,810 Speaker 1: because those were the two Fahrenheits that the news story 425 00:23:36,930 --> 00:23:41,850 Speaker 1: kept flipping between two degrees celsius is thirty six degrees 426 00:23:42,090 --> 00:23:46,970 Speaker 1: fahrenheit and two degrees celsius is three point six degrees fahrenheit, 427 00:23:47,090 --> 00:23:50,530 Speaker 1: depending on if that's an absolute temperature or a change 428 00:23:50,570 --> 00:23:53,610 Speaker 1: in temperature. And it's easy to make this mistake because 429 00:23:53,610 --> 00:23:56,890 Speaker 1: things like kilograms and pounds they both start at zero. 430 00:23:57,090 --> 00:23:59,250 Speaker 1: You've got zero mass and then you have some mass, 431 00:23:59,330 --> 00:24:02,730 Speaker 1: and meters and feet both start at zero. Doesn't make 432 00:24:02,770 --> 00:24:05,370 Speaker 1: a difference if you're talking about the difference in two 433 00:24:05,410 --> 00:24:08,930 Speaker 1: people's height or anything. It changes versus absolute, same deal. 434 00:24:09,530 --> 00:24:12,650 Speaker 1: Celsius and Fahrenheits start at different points. They're zeros, are 435 00:24:12,690 --> 00:24:16,970 Speaker 1: at different places, and their increments are different. Like if 436 00:24:16,970 --> 00:24:21,490 Speaker 1: you're outside and it's two degrees celsius actual temperature and 437 00:24:21,570 --> 00:24:23,970 Speaker 1: you look at a thermometer, it would say two degrees 438 00:24:24,010 --> 00:24:29,930 Speaker 1: celsius thirty six degrees fahrenheit absolute temperature. But if it 439 00:24:29,970 --> 00:24:34,370 Speaker 1: then went up another two degrees, the temperature wouldn't go 440 00:24:34,490 --> 00:24:37,250 Speaker 1: up another thirty six degrees fahrenheit, it would go up 441 00:24:37,250 --> 00:24:41,730 Speaker 1: another three point six degrees fahrenheit, because that's the relative 442 00:24:42,010 --> 00:24:44,850 Speaker 1: ratio between the increments. So you've got a factor in 443 00:24:44,890 --> 00:24:47,650 Speaker 1: where they start how much they change. And because those 444 00:24:47,690 --> 00:24:52,370 Speaker 1: numbers look very similar, I can imagine why someone like 445 00:24:52,690 --> 00:24:55,450 Speaker 1: looked at the news story and went, oh, they've put 446 00:24:55,890 --> 00:24:58,290 Speaker 1: they put three point six. It should be thirty six. 447 00:24:58,610 --> 00:25:00,850 Speaker 1: They put the decimal point in the wrong place. Or 448 00:25:00,890 --> 00:25:03,250 Speaker 1: I'm guessing if you type this into Google or a 449 00:25:03,250 --> 00:25:06,730 Speaker 1: similar website and ask for the conversion, you know, what 450 00:25:06,850 --> 00:25:10,290 Speaker 1: is two degrees centigrade in fahrenheit. I mean, the answer 451 00:25:10,330 --> 00:25:13,330 Speaker 1: to that question is ambiguous, but Google is probably going 452 00:25:13,410 --> 00:25:16,770 Speaker 1: to return thirty six fahrenheit because that is the most 453 00:25:16,770 --> 00:25:20,090 Speaker 1: common sort of instance people thinking about the weather. Yeah, 454 00:25:20,130 --> 00:25:22,450 Speaker 1: the vast mirror of people are looking for the absolute temperature. 455 00:25:22,530 --> 00:25:24,130 Speaker 1: That's what Google is going to give you back. But 456 00:25:24,250 --> 00:25:27,410 Speaker 1: this was a percentage change in global warming should have 457 00:25:27,410 --> 00:25:31,170 Speaker 1: been three point six. Eventually, their solution was just not 458 00:25:31,250 --> 00:25:33,850 Speaker 1: to give it in fahrenheit, which is a solution I 459 00:25:33,890 --> 00:25:38,890 Speaker 1: wholeheartedly agree with just avoiding the problem, but just give 460 00:25:38,930 --> 00:25:41,690 Speaker 1: it in celsius and move on. As a journalist, it 461 00:25:41,770 --> 00:25:44,410 Speaker 1: is surprising how often you can solve a problem by 462 00:25:44,450 --> 00:25:47,890 Speaker 1: just deleting the sentence you're struggling with, ideally before you 463 00:25:47,970 --> 00:25:50,690 Speaker 1: hit publish. But you know it doesn't always work out 464 00:25:50,690 --> 00:25:52,930 Speaker 1: like that. So the story, as we've mentioned, comes from 465 00:25:52,970 --> 00:25:54,970 Speaker 1: your book Humble Pie, and it's one of dozens and 466 00:25:55,010 --> 00:25:57,730 Speaker 1: dozens of stories. A Humble Pie is not your first 467 00:25:57,730 --> 00:26:00,890 Speaker 1: book about fun maths. Why did you turn to the 468 00:26:00,930 --> 00:26:05,250 Speaker 1: topic of mistakes. I mean, because I've previously written about 469 00:26:05,370 --> 00:26:07,650 Speaker 1: kind of enjoying mass doing it, having some fun with it. 470 00:26:07,770 --> 00:26:10,250 Speaker 1: I thought, you know what, maths, it's wonderful, it's lovely, 471 00:26:10,290 --> 00:26:12,050 Speaker 1: we play with it. I think it's great, but we 472 00:26:12,170 --> 00:26:14,170 Speaker 1: do use it in a lot of critical situations, and 473 00:26:14,210 --> 00:26:16,210 Speaker 1: we use it like it's behind the scenes in our 474 00:26:16,250 --> 00:26:18,130 Speaker 1: modern society and we never really notice it. And so 475 00:26:18,170 --> 00:26:19,930 Speaker 1: I thought, you know what, if I write a book 476 00:26:20,170 --> 00:26:25,010 Speaker 1: about maths mistakes, I can tick two boxes simultaneously. Partly, 477 00:26:25,210 --> 00:26:27,210 Speaker 1: it means people want to read it. I mean, people 478 00:26:27,690 --> 00:26:30,410 Speaker 1: love things going wrong, as this podcast is a testament 479 00:26:30,410 --> 00:26:34,370 Speaker 1: too right, and we can learn learn from these terrible situations. 480 00:26:34,570 --> 00:26:35,890 Speaker 1: And so I was like, Okay, there'll be a good 481 00:26:35,890 --> 00:26:39,050 Speaker 1: hook to get people reading a book about mathematics, and 482 00:26:39,410 --> 00:26:42,130 Speaker 1: because I'm telling stories of mass going wrong, it's an 483 00:26:42,210 --> 00:26:45,050 Speaker 1: excellent excuse to first of all, have to set up 484 00:26:45,130 --> 00:26:47,210 Speaker 1: what the maths is and why we're using it. So 485 00:26:47,570 --> 00:26:51,930 Speaker 1: it justifies me writing about all these fantastic situations where 486 00:26:51,970 --> 00:26:57,170 Speaker 1: maths makes our modern society possible, which I found deeply pleasing. 487 00:26:57,410 --> 00:27:01,810 Speaker 1: One more thought, Matt Air, Canada have made this mistake twice. 488 00:27:02,370 --> 00:27:07,210 Speaker 1: NASA have made this mistake. Sixteenth century Swedish shipwrights have 489 00:27:07,330 --> 00:27:09,850 Speaker 1: made this mistake. The BBC have made this mistake. I mean, 490 00:27:10,210 --> 00:27:13,010 Speaker 1: this sort of problem seems to be absolutely all around us, 491 00:27:13,130 --> 00:27:16,450 Speaker 1: and it's the kind of thing that does bring planes 492 00:27:16,490 --> 00:27:19,250 Speaker 1: out of the sky and causes bridges to collapse? Does it? 493 00:27:19,290 --> 00:27:22,490 Speaker 1: Does it make you nervous knowing that we're trusting all 494 00:27:22,530 --> 00:27:24,370 Speaker 1: of these people all around us to get these things 495 00:27:24,450 --> 00:27:28,690 Speaker 1: right and they sometimes don't. It doesn't. It doesn't. So 496 00:27:29,290 --> 00:27:32,330 Speaker 1: then the underlying issue is as humans, we're not naturally 497 00:27:32,330 --> 00:27:35,210 Speaker 1: good at mathematics. And that's kind of reassuring because everyone 498 00:27:35,250 --> 00:27:37,690 Speaker 1: has ever struggled with maths or found it difficult. We 499 00:27:37,770 --> 00:27:40,850 Speaker 1: all do. Everyone finds maths difficult. The human brain doesn't 500 00:27:40,890 --> 00:27:45,530 Speaker 1: do maths like natively, it's going to learn it. But 501 00:27:45,770 --> 00:27:49,570 Speaker 1: thankfully that's not reassuring at all. I'm not reassured by 502 00:27:49,570 --> 00:27:52,410 Speaker 1: the thought that the people be fueling planes can't doing maths. 503 00:27:52,610 --> 00:27:56,130 Speaker 1: That's a valid point, allow me to continue. But what 504 00:27:56,210 --> 00:27:59,890 Speaker 1: I do find, what I do like is, and I'll 505 00:27:59,890 --> 00:28:03,930 Speaker 1: try and land this with a nice happy conclusion that 506 00:28:04,210 --> 00:28:06,930 Speaker 1: because we have maths, we can do so much more 507 00:28:06,930 --> 00:28:09,050 Speaker 1: than our brains can do. Intuitively, we don't have to 508 00:28:09,290 --> 00:28:12,210 Speaker 1: design like we have to make a building by eyeballing 509 00:28:12,210 --> 00:28:15,250 Speaker 1: it and like super over engineering it. We can actually 510 00:28:15,290 --> 00:28:17,490 Speaker 1: do the mathmakes and work out exactly what we need 511 00:28:17,650 --> 00:28:20,210 Speaker 1: and how it's going to work, and using maths we 512 00:28:20,290 --> 00:28:23,050 Speaker 1: can do far more than the human brain was ever 513 00:28:23,130 --> 00:28:26,050 Speaker 1: designed to do. The cost, however, is that we are 514 00:28:26,090 --> 00:28:28,370 Speaker 1: beyond our intuition and we have to do the maths 515 00:28:28,490 --> 00:28:31,050 Speaker 1: and do it very carefully and double check everything. And 516 00:28:31,130 --> 00:28:33,730 Speaker 1: so I like the fact we can achieve so much 517 00:28:33,770 --> 00:28:36,730 Speaker 1: more because we can use maths. I accept that this 518 00:28:36,850 --> 00:28:39,690 Speaker 1: is the cost it comes with, and I'm also reassured 519 00:28:39,930 --> 00:28:43,090 Speaker 1: all the stories I found, Obviously they're very spectacular, they're 520 00:28:43,170 --> 00:28:45,170 Speaker 1: very interesting, there's a lot to learn. I love the 521 00:28:45,210 --> 00:28:48,130 Speaker 1: fact now students at school are told pay attention to 522 00:28:48,210 --> 00:28:51,210 Speaker 1: units otherwise these things can happen. They are the exception. 523 00:28:51,570 --> 00:28:53,970 Speaker 1: The vast majority of the time, we've got all these 524 00:28:53,970 --> 00:28:57,450 Speaker 1: redundancies and checks in place, and they work. And so 525 00:28:57,890 --> 00:29:01,930 Speaker 1: these stories are interesting because they are such freak occurrence 526 00:29:01,970 --> 00:29:05,370 Speaker 1: as they managed to slip through, and thankfully, with a 527 00:29:05,490 --> 00:29:10,050 Speaker 1: very statistic minded head, I can still happily lie knowing 528 00:29:10,090 --> 00:29:13,210 Speaker 1: that the vast majority of the time it works. Fine, Matt, 529 00:29:13,450 --> 00:29:14,890 Speaker 1: What else are you working on at the moment, and 530 00:29:15,290 --> 00:29:19,130 Speaker 1: where else can people find your stuff? Oh? My gods. Well, 531 00:29:19,170 --> 00:29:23,130 Speaker 1: I'm still writing away on a new book which will 532 00:29:23,170 --> 00:29:26,330 Speaker 1: be out at some point in the distant future, you 533 00:29:26,410 --> 00:29:28,170 Speaker 1: know what. I don't think it's been announced, but it'll 534 00:29:28,170 --> 00:29:32,450 Speaker 1: be a book about trigonometry. So that's a Cautionary Tales 535 00:29:32,570 --> 00:29:37,690 Speaker 1: exclusive trigonometry book coming up at some point when I 536 00:29:37,770 --> 00:29:40,050 Speaker 1: finished writing it. If you'd like to know when you 537 00:29:40,130 --> 00:29:43,330 Speaker 1: sound a lot like my editor around that, I'm still 538 00:29:43,370 --> 00:29:47,210 Speaker 1: doing a lot of work obviously on YouTube and live 539 00:29:47,210 --> 00:29:50,450 Speaker 1: works picking up again. I just actually I just filmed 540 00:29:50,970 --> 00:29:55,050 Speaker 1: the stand up special version of Humble Pie. So I 541 00:29:55,090 --> 00:29:57,690 Speaker 1: was on tour with the show that goes with the book. 542 00:29:58,250 --> 00:30:01,130 Speaker 1: In twenty nineteen into twenty twenty. We obviously had to 543 00:30:01,170 --> 00:30:04,130 Speaker 1: delay and cancel a lot of those shows, and we 544 00:30:04,250 --> 00:30:07,050 Speaker 1: only just filmed the stand Up Special a month or 545 00:30:07,090 --> 00:30:10,530 Speaker 1: two ago, and that will be out at some point 546 00:30:10,570 --> 00:30:12,650 Speaker 1: around September. So if people want to see the live 547 00:30:12,770 --> 00:30:15,130 Speaker 1: stage version of all of these, if you've heard of 548 00:30:15,130 --> 00:30:17,610 Speaker 1: at a stand Up Mass dot com, that's my website 549 00:30:17,610 --> 00:30:20,250 Speaker 1: where everything happens. And if you're going to YouTube dot 550 00:30:20,290 --> 00:30:22,530 Speaker 1: com slash stand Up Mass, you'll see all of my 551 00:30:22,650 --> 00:30:26,570 Speaker 1: videos as and when they come out. Matt Parker, thank 552 00:30:26,570 --> 00:30:28,890 Speaker 1: you very much for joining us on Cautionary Tales. Tim 553 00:30:28,930 --> 00:30:35,970 Speaker 1: has been my absolute pleasure. Cautionary Tales is written by 554 00:30:35,970 --> 00:30:40,010 Speaker 1: me Tim Harford with Andrew Wright. It's produced by Ryan 555 00:30:40,090 --> 00:30:43,890 Speaker 1: Dilley with support from Courtney Guarino and Emily Vaughan. The 556 00:30:44,050 --> 00:30:47,850 Speaker 1: sound design and original music is the work of Pascal Wise. 557 00:30:48,370 --> 00:30:51,770 Speaker 1: It features the voice talents of Ben Crow, Melanie Gutridge, 558 00:30:52,050 --> 00:30:55,970 Speaker 1: Stella Harford, and Rufus Wright. The show also wouldn't have 559 00:30:56,010 --> 00:30:59,530 Speaker 1: been possible without the work of Mia LaBelle, Jacob Weisberg, 560 00:30:59,810 --> 00:31:04,890 Speaker 1: Heather Fane, John Schnas, Julia Barton, Kylie mcgliori, Eric Sandler, 561 00:31:05,170 --> 00:31:10,770 Speaker 1: Royston Berserv, Maggie Taylor, Nicole Murano, Danielle kan and Maya Caning. 562 00:31:11,530 --> 00:31:15,530 Speaker 1: Cautionary Tales is a production of Pushkin Industries. If you 563 00:31:15,610 --> 00:31:18,690 Speaker 1: like the show, please remember to share, rate and review, 564 00:31:19,010 --> 00:31:21,450 Speaker 1: Tell a friend, Tell two friends, and if you want 565 00:31:21,490 --> 00:31:23,850 Speaker 1: to hear the show, adds free and listen to four 566 00:31:24,090 --> 00:31:28,810 Speaker 1: exclusive Cautionary Tales shorts. 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