WEBVTT 1 00:00:00.120 --> 00:00:03.359 Picture this. You are sitting in the darkened cabin of 2 00:00:03.359 --> 00:00:04.759 British Airways flight nine. 3 00:00:05.080 --> 00:00:06.919 Oh, this is such a terrifying one. 4 00:00:07.120 --> 00:00:10.080 I mean, it's June twenty fourth, nineteen eighty two. You've 5 00:00:10.119 --> 00:00:14.400 been flying for hours, just cruising peacefully at thirty seven 6 00:00:14.439 --> 00:00:18.920 thousand feet over the pitch black Indian Ocean, heading toward Australia, and. 7 00:00:18.920 --> 00:00:20.280 You're probably exhausted at that point. 8 00:00:20.480 --> 00:00:23.239 Exactly, you're exhausted. You look out the window into just 9 00:00:23.359 --> 00:00:27.480 total absolute darkness. But then suddenly the windshield and the 10 00:00:27.480 --> 00:00:32.479 cockpit is illuminated by this eerie, brilliant white glow. 11 00:00:32.880 --> 00:00:36.399 Yeah, and to the pilots it looks exactly like sant Elmo's. 12 00:00:36.000 --> 00:00:37.359 Fire, which is what exactly. 13 00:00:37.600 --> 00:00:40.679 It's a crackling electrical sort of spider wave halo you 14 00:00:40.679 --> 00:00:43.799 sometimes see dancing across the glass during heavy thunderstorms. 15 00:00:43.840 --> 00:00:46.560 Okay, but here's the crazy part. There isn't a single 16 00:00:46.600 --> 00:00:49.320 storm cloud on the weather radar. I mean, the sky 17 00:00:49.479 --> 00:00:51.119 is completely. 18 00:00:50.520 --> 00:00:53.560 Clear, completely empty, which makes it so much worse. 19 00:00:53.759 --> 00:00:57.240 Yeah, and then this strange glow just gets worse. Smoke 20 00:00:57.280 --> 00:01:00.200 starts pouring into the passenger cabin through the air conditioning vents. 21 00:01:00.039 --> 00:01:02.280 And it doesn't smell like normal smoke, right, No. 22 00:01:02.240 --> 00:01:05.640 It smells thick and acrid like sulfur. So you look 23 00:01:05.680 --> 00:01:08.280 out the window again and your blood just runs cold 24 00:01:08.760 --> 00:01:12.680 because there are huge forty foot jets of sheer, blinding 25 00:01:12.719 --> 00:01:14.040 flames shooting out the back. 26 00:01:13.959 --> 00:01:16.719 Of the engines, which is just I mean, incomprehensible as 27 00:01:16.760 --> 00:01:17.359 a passenger. 28 00:01:17.439 --> 00:01:22.280 And then the engines make this horrible grating, rumbling sound 29 00:01:22.439 --> 00:01:26.519 like metal literally tearing itself apart, and they die, all 30 00:01:26.560 --> 00:01:29.760 four of them. Lital silence, absolute silence. You are suddenly 31 00:01:29.799 --> 00:01:32.879 falling from the sky in a three hundred ton glider. 32 00:01:33.359 --> 00:01:36.760 It is the ultimate nightmare scenario. I mean, they drop 33 00:01:36.799 --> 00:01:39.239 for miles, just completely helpless in the dark, and. 34 00:01:39.159 --> 00:01:42.519 The crew is trying, what just desperately to restart them. 35 00:01:42.400 --> 00:01:45.280 Again and again, but they get absolutely nothing. So finally, 36 00:01:45.319 --> 00:01:48.120 at around twelve thousand feet, right as the captin prepares 37 00:01:48.159 --> 00:01:51.359 to make a completely blind, undoubtedly fatal ditch into the 38 00:01:51.439 --> 00:01:52.159 rough open. 39 00:01:51.920 --> 00:01:54.120 Sea, the engine's miraculously roar back to life. 40 00:01:54.200 --> 00:01:56.400 Yeah. One by one they catch yeah, and the crew 41 00:01:56.439 --> 00:01:58.400 manages to pull the seven forty seven out of its 42 00:01:58.439 --> 00:02:00.239 dive and they actually limp to a safe lygd ending 43 00:02:00.239 --> 00:02:01.200 in Jakarta. 44 00:02:00.920 --> 00:02:04.400 Which is just this incredible story of survival. But the 45 00:02:04.400 --> 00:02:08.319 truly fascinating part of our deep dive today starts when 46 00:02:08.360 --> 00:02:10.800 investigators finally look at that plane on the. 47 00:02:10.759 --> 00:02:14.879 Ground, because what they found completely changed modern aviation. 48 00:02:15.199 --> 00:02:18.000 It really did. Today, you and I are basically stepping 49 00:02:18.039 --> 00:02:21.039 into the shoes of the investigators. We're digging into the 50 00:02:21.039 --> 00:02:24.479 flight recorders, the crash reports, the twisted metal, all of it, 51 00:02:25.159 --> 00:02:27.439 just to understand the hidden mechanisms of flight. 52 00:02:27.840 --> 00:02:30.879 Because everyone always says the sky is the safest place 53 00:02:30.879 --> 00:02:34.039 on Earth, and statistically it absolutely is right. 54 00:02:34.080 --> 00:02:37.280 But the aviation Safety Manual, it is written entirely in blood. 55 00:02:37.639 --> 00:02:41.240 Literally every single safety feature on a modern commercial jet, 56 00:02:41.400 --> 00:02:43.120 from the lights on the floor to the software and 57 00:02:43.159 --> 00:02:48.159 the cockpit exists because someone somewhere paid the ultimate price right. 58 00:02:48.080 --> 00:02:51.000 And the clues left behind in these disasters reveal exactly 59 00:02:51.039 --> 00:02:54.800 how these invisible threats and mechanical ghosts and the fragile 60 00:02:54.840 --> 00:02:57.360 limits of the human mind revolutionize the way we fly. 61 00:02:57.800 --> 00:03:01.120 So let's look at the clues from British Aways flight nine. 62 00:03:01.360 --> 00:03:03.919 Yeah, because when they inspected the seven forty seven on 63 00:03:03.960 --> 00:03:06.960 the ground, the paint was practically sand blasted off the 64 00:03:07.000 --> 00:03:10.639 nose of the plane. The engines were totally choked with 65 00:03:10.719 --> 00:03:13.400 this fine dust and pieces of hardened rock. 66 00:03:13.840 --> 00:03:15.520 So it wasn't a mechanical failure at all. 67 00:03:15.680 --> 00:03:19.960 No, it was Mount Galungum, a volcano one hundred and 68 00:03:19.960 --> 00:03:24.439 sixty kilometers away, had erupted and sent this massive cloud 69 00:03:24.479 --> 00:03:27.039 of ash directly into their flight path. 70 00:03:27.159 --> 00:03:28.840 But this is where people get confused. 71 00:03:28.879 --> 00:03:30.759 Oh yeah, this is where my brand stalls out on 72 00:03:30.800 --> 00:03:33.759 this because volcanic ash. You know, when you think about it, it 73 00:03:33.560 --> 00:03:36.759 sounds like soft, powdery dust you'd sweep out of a fireplace, 74 00:03:36.879 --> 00:03:39.240 right exactly. I can see it clogging a filter, sure, 75 00:03:39.800 --> 00:03:43.280 but how does a cloud of dust completely assassinate four 76 00:03:43.479 --> 00:03:45.719 massive jet engines simultaneously? 77 00:03:46.039 --> 00:03:49.400 And that is the exact misconception that nearly killed everyone 78 00:03:49.439 --> 00:03:52.840 on board, Because volcanic ash isn't soft wood ash, right, 79 00:03:52.919 --> 00:03:57.919 It's basically pulverized rock, glass, and minerals. Under a microscope, 80 00:03:57.960 --> 00:04:00.800 it's incredibly sharp, jagged, and so. 81 00:04:00.719 --> 00:04:03.360 That's what Sam blasted the windshields so badly. The pilots 82 00:04:03.400 --> 00:04:04.960 couldn't even see out of it exactly. 83 00:04:05.520 --> 00:04:09.000 But the real lethal threat is the thermodynamics. Okay, unpack 84 00:04:09.080 --> 00:04:12.120 that for me, So inside a jet engine's combustion chamber 85 00:04:12.240 --> 00:04:15.840 where the fuel is actually ignited. The operating temperature sits 86 00:04:15.840 --> 00:04:20.360 around two thousand degrees celsius, but volcanic ash being pulverized 87 00:04:20.439 --> 00:04:23.000 rock melts set around fourteen hundred degrees. 88 00:04:23.120 --> 00:04:25.639 Oh wow, So they essentially flew into a cloud of 89 00:04:25.680 --> 00:04:28.720 glass and turned their engines into flying kilns. 90 00:04:28.839 --> 00:04:32.759 Yes, exactly, they suffocated their own engines with molten rock. 91 00:04:33.360 --> 00:04:37.199 The engines inhaled thousands of pounds of this abrasive material, 92 00:04:37.600 --> 00:04:41.439 melted it instantly into this sticky molten goo, and it 93 00:04:41.560 --> 00:04:42.879 coated the turbine. 94 00:04:42.480 --> 00:04:45.160 Blades just completely choked off the internal air flaw. 95 00:04:45.279 --> 00:04:48.240 Right, so the engines choked. They backfired, which caused those 96 00:04:48.319 --> 00:04:51.199 massive forty foot flames shooting out the back, and then 97 00:04:51.199 --> 00:04:52.439 they stalled out completely. 98 00:04:52.480 --> 00:04:55.120 But wait, if the engines were literally coated in molten rock, 99 00:04:55.160 --> 00:04:57.839 how on earth did they restart at twelve thousand feet? 100 00:04:57.959 --> 00:05:00.560 And that is the beautiful physics of the offe moment 101 00:05:00.639 --> 00:05:03.800 for the investigators. Okay, when the engines died, they stopped 102 00:05:03.800 --> 00:05:06.480 generating that two thousand degree heat, so as the plane 103 00:05:06.519 --> 00:05:08.600 fell out of the sky, it dropped below the ash 104 00:05:08.680 --> 00:05:10.199 cloud into clean, freezing air. 105 00:05:10.360 --> 00:05:11.680 Oh, I see where this is going. 106 00:05:11.959 --> 00:05:16.199 Yeah, the engines cooled rapidly, that sticky molten rock solidified, 107 00:05:16.560 --> 00:05:19.360 turned brittle, and basically shattered, So the. 108 00:05:19.279 --> 00:05:23.319 Forward momentum of the falling plane literally blew the shattered 109 00:05:23.399 --> 00:05:25.439 rock out the back of the engines exactly. 110 00:05:25.720 --> 00:05:28.079 Once the core was cleared out, the crew was finally 111 00:05:28.079 --> 00:05:30.879 able to get a spark to catch and restart the turbines. 112 00:05:31.000 --> 00:05:34.199 That is wild, and because of Flight nine, the aviation 113 00:05:34.319 --> 00:05:37.360 world learned this terrifying lesson. I mean, volcanic ash is 114 00:05:37.480 --> 00:05:41.240 completely invisible to standard aircraft weather radar because it's. 115 00:05:41.120 --> 00:05:44.839 Dry, right, radar bounces off moisture. No moisture, no radar return. 116 00:05:45.240 --> 00:05:49.600 So today geological agencies and airlines are just constantly communicating 117 00:05:49.639 --> 00:05:52.560 to track these invisible ash clouds via satellite. So no 118 00:05:52.720 --> 00:05:55.199 plane ever flies into a volcano's exhaust again. 119 00:05:55.240 --> 00:05:57.240 But you know that was an invisible threat outside the 120 00:05:57.279 --> 00:06:00.959 aircraft sometimes the most insidious threat to the ones building 121 00:06:01.040 --> 00:06:02.759 up quietly right beneath your feet. 122 00:06:02.839 --> 00:06:06.560 Oh, absolutely, which brings us to June nineteen eighty three 123 00:06:06.680 --> 00:06:10.199 Air Canada Flight seven ninety seven, a DC nine, flying 124 00:06:10.199 --> 00:06:11.480 from Dallas to Toronto. 125 00:06:11.600 --> 00:06:12.839 This one starts so innocently. 126 00:06:12.879 --> 00:06:16.319 It's chilling, it really is. They're cruising smoothly. At thirty 127 00:06:16.319 --> 00:06:20.120 three thousand feet. The crew hears three circuit breakers pop 128 00:06:20.160 --> 00:06:23.800 at the back of the plane, specifically the breakers tied 129 00:06:23.839 --> 00:06:25.639 to the flush motor in the rear. 130 00:06:25.639 --> 00:06:29.040 Washroom and in the cockpit. A popped circuit breaker isn't 131 00:06:29.040 --> 00:06:30.759 an emergency. It's usually just. 132 00:06:30.680 --> 00:06:32.560 A nuisance, like a power surge or something. 133 00:06:32.639 --> 00:06:35.720 Yeah, power surge a mechanical hiccup. You try to reset 134 00:06:35.720 --> 00:06:37.399 it and if it doesn't hold, you just tape it 135 00:06:37.439 --> 00:06:38.720 off and write it up for maintenance. 136 00:06:38.839 --> 00:06:42.120 And that's exactly what the captain thought. But fifteen minutes later, 137 00:06:42.319 --> 00:06:47.920 a passenger notices a strange, wiry smell, like burning plastic. 138 00:06:48.000 --> 00:06:50.199 Always a bad sign on a plane, right, So. 139 00:06:50.199 --> 00:06:52.240 A flight atten and goes to the back, opens the 140 00:06:52.319 --> 00:06:55.959 washroom door, and this thick, toxic smoke starts creeping out 141 00:06:56.000 --> 00:06:59.160 into the cabin. There are no visible flames. 142 00:06:58.800 --> 00:07:01.839 Anywhere, thisoxious, expanding cloud of smoke. 143 00:07:01.959 --> 00:07:06.120 Yeah, so the crew initiates a desperate emergency descent into Cincinnati. 144 00:07:06.519 --> 00:07:08.519 By the time they hit their runway, the cabin is 145 00:07:08.560 --> 00:07:11.199 pitch black from the soot. Me you can't see your 146 00:07:11.240 --> 00:07:12.879 hand in front of your face passage. 147 00:07:12.519 --> 00:07:14.360 As a choking struggling to breathe. 148 00:07:14.399 --> 00:07:18.639 But miraculously, the pilots actually manage a completely blind landing. 149 00:07:18.959 --> 00:07:22.040 They get the plane on the ground, the tires screeched 150 00:07:22.040 --> 00:07:24.480 to a halt. You'd think the nightmare is over right, 151 00:07:24.560 --> 00:07:26.680 You'd think they survived, but they didn't. 152 00:07:26.839 --> 00:07:30.360 They opened the emergency doors to evacuate, and ninety seconds 153 00:07:30.399 --> 00:07:33.399 after those doors open, the entire interior of the plane 154 00:07:33.519 --> 00:07:35.560 erupts in a massive flash. 155 00:07:35.319 --> 00:07:36.800 Fire, just devastating. 156 00:07:37.040 --> 00:07:39.879 Twenty three people died in their seats, including the rising 157 00:07:39.920 --> 00:07:43.480 folk music star Stan Rogers. They were just seconds away 158 00:07:43.560 --> 00:07:45.600 from stepping onto the tarmac. 159 00:07:45.240 --> 00:07:49.519 Which forces investigators to ask this huge question, why did 160 00:07:49.519 --> 00:07:52.680 it explode after they were safely on the ground, Right. 161 00:07:52.519 --> 00:07:54.160 It doesn't make sense initially. 162 00:07:53.839 --> 00:07:57.360 No, But when the National Transportation Safety Board the NTSB 163 00:07:57.959 --> 00:08:01.839 dug into the charred remains, they uncovered the terrifying chemistry 164 00:08:01.879 --> 00:08:03.279 of incomplete combustion. 165 00:08:03.560 --> 00:08:04.519 Okay, what does that mean? 166 00:08:04.800 --> 00:08:06.959 So an electrical fire had started behind the walls of 167 00:08:07.000 --> 00:08:10.040 the washroom, but it was starved of oxygen inside that 168 00:08:10.120 --> 00:08:13.639 tight fuselage space, so instead of burning cleanly, the wall 169 00:08:13.680 --> 00:08:17.360 spaces acted like a chimney oh wow, Yeah, pumping incredibly hot, 170 00:08:17.399 --> 00:08:20.800 combustible toxic gases straight up into the ceiling paneling of 171 00:08:20.839 --> 00:08:22.040 the passenger cabin. 172 00:08:22.000 --> 00:08:24.439 So it was just hovering right above their heads. The 173 00:08:24.639 --> 00:08:29.279 entire descent, just this hidden toxic cloud packed with carbon 174 00:08:29.360 --> 00:08:31.560 monoxide and hydrogen cyanide. 175 00:08:31.199 --> 00:08:33.759 Yes, And because it was stars of oxygen, it couldn't 176 00:08:33.759 --> 00:08:36.399 fully ignite. It just baked the interior. 177 00:08:36.600 --> 00:08:39.120 But then they opened the doors exactly. 178 00:08:39.000 --> 00:08:41.639 When they landed, and popped open the overwing exits and 179 00:08:41.720 --> 00:08:45.639 the main doors, an unlimited supply of fresh, cool oxygen 180 00:08:45.919 --> 00:08:49.639 rushed into the cabin. It mixed instantly with those superheated 181 00:08:49.639 --> 00:08:52.600 gases trapped in the ceiling, and it triggered a flash over. 182 00:08:52.879 --> 00:08:56.399 So the entire cabin ignited simultaneously. 183 00:08:55.600 --> 00:08:58.639 Instantly burning all the available oxygen in the plane. 184 00:08:58.759 --> 00:09:01.519 That is just horrified. But think about the last time 185 00:09:01.600 --> 00:09:04.759 you boarded a flight. You probably noticed those floor track 186 00:09:04.840 --> 00:09:07.639 lights illuminating the aisle guiding you to the exite. You 187 00:09:07.679 --> 00:09:11.200 probably notice the smoke detectors installed in every single lavatory, 188 00:09:11.559 --> 00:09:15.039 or those heavy halin fire extinguishers the crew carries. You 189 00:09:15.120 --> 00:09:17.000 might take them for granted, but you are sitting in 190 00:09:17.039 --> 00:09:19.480 the legacy of Air Canada flights seven nine to seven 191 00:09:19.639 --> 00:09:20.440 because every. 192 00:09:20.279 --> 00:09:23.440 One of those features was mandated specifically because of the 193 00:09:23.480 --> 00:09:26.120 people who didn't make it off that runway in Cincinnati. 194 00:09:26.320 --> 00:09:29.639 They finally understood that smoke and fire don't just damage 195 00:09:29.679 --> 00:09:32.840 the plane. They totally changed the chemical environment of the cabin. 196 00:09:33.080 --> 00:09:36.519 Yeah, but you know, with fire, investigators at least have 197 00:09:36.559 --> 00:09:41.600 physical clues melted wires, scorch marks, soot patterns. The most 198 00:09:41.679 --> 00:09:44.559 terrifying investigations are the ones where a plane falls out 199 00:09:44.559 --> 00:09:48.720 of a perfectly clear sky, obliterates on impact, and leaves 200 00:09:48.759 --> 00:09:51.720 absolutely zero physical evidence behind. 201 00:09:51.559 --> 00:09:56.600 The mechanical ghosts exactly. So imagine flying on a beautiful 202 00:09:56.679 --> 00:10:00.919 windless day, you are just moments from touchdown, landing gears down, 203 00:10:00.960 --> 00:10:03.639 you can clearly see the runway, and suddenly the plane 204 00:10:03.679 --> 00:10:06.639 just violently flips onto its side and dives straight into 205 00:10:06.679 --> 00:10:09.480 the ground. It's unthinkable, but that is exactly what happened 206 00:10:09.519 --> 00:10:11.879 to United Flight five eighty five in Colorado Springs in 207 00:10:11.960 --> 00:10:14.200 nineteen ninety one, and then again to US Air Flight 208 00:10:14.240 --> 00:10:16.919 four to twenty seven in Pittsburgh in nineteen ninety four. 209 00:10:17.200 --> 00:10:20.519 Both were bowing seven thirty sevens. Both were on their final. 210 00:10:20.279 --> 00:10:23.080 Approach, and both violently rolled out of the sky in 211 00:10:23.120 --> 00:10:25.200 a matter of ten seconds. No survivors. 212 00:10:25.320 --> 00:10:28.759 For accident investigators, tracking down the cause of these two 213 00:10:28.799 --> 00:10:31.759 crashes was literally the equivalent of hunting a phantom. 214 00:10:31.840 --> 00:10:33.600 They had nothing to go on, right, nothing. 215 00:10:34.240 --> 00:10:37.919 The NTSB spent ten agonizing years trying to find the cause. 216 00:10:38.559 --> 00:10:42.159 It was the longest most expensive investigation in aviation history. 217 00:10:42.639 --> 00:10:44.919 They tested everything I read. 218 00:10:44.919 --> 00:10:48.759 They even flew planes into dangerous mountain wind rotors just 219 00:10:48.799 --> 00:10:49.600 to see what would happen. 220 00:10:49.799 --> 00:10:54.480 They did. They tested for freak electromagnetic interference, scrambling the 221 00:10:54.519 --> 00:10:56.840 computers too. Nothing made sense. 222 00:10:56.639 --> 00:10:59.320 Except for one clue, right yeah, The only physical clue 223 00:10:59.360 --> 00:11:03.000 they had was that in both wreckage sites, the rudder 224 00:11:03.279 --> 00:11:05.320 you know, the massive vertical flap on the tail that 225 00:11:05.360 --> 00:11:08.360 steers the nose left and right, had slammed completely to 226 00:11:08.399 --> 00:11:09.480 one side and stayed there. 227 00:11:09.519 --> 00:11:11.960 But they had no idea why. None, And they literally 228 00:11:12.000 --> 00:11:14.600 had nothing until a freezing day in nineteen ninety six. 229 00:11:15.279 --> 00:11:20.080 East Wind Flight five seventeen is approaching Richmond, Virginia. Suddenly 230 00:11:20.120 --> 00:11:21.639 the plane aggressively. 231 00:11:21.159 --> 00:11:22.960 Rolls to the right, just like the others. 232 00:11:23.080 --> 00:11:26.080 Just like the others. Captain Brian Bishop steps hard on 233 00:11:26.120 --> 00:11:28.600 the opposite left rudder pedal to level the plane out, 234 00:11:28.759 --> 00:11:31.440 and the pedal will not budge. It is locked. 235 00:11:31.120 --> 00:11:33.080 Solid, which is a pilot's worst nightmare. 236 00:11:33.360 --> 00:11:38.120 For thirty terrifying seconds, they're flying practically sideways, wrestling the 237 00:11:38.159 --> 00:11:42.480 control column. Then, just as mysteriously as it started, a 238 00:11:42.559 --> 00:11:45.960 loud pop echoes through the floorboards and the rudder snaps back. 239 00:11:45.879 --> 00:11:47.600 To normal and they managed to land safely. 240 00:11:48.440 --> 00:11:52.200 Yes, so, finally, after a decade of ghosts, the NTSB 241 00:11:52.639 --> 00:11:55.879 had an intact airplane and a living pilot. 242 00:11:56.000 --> 00:11:59.720 And incredibly, they still almost missed it. Wait, how well 243 00:11:59.759 --> 00:12:02.799 they poled the power control unit, the hydraulic mechanical muscle 244 00:12:02.799 --> 00:12:05.120 that actually moves the rudder on the tail, and put 245 00:12:05.120 --> 00:12:07.240 it on a test bench. They ran it over and 246 00:12:07.279 --> 00:12:08.919 over and it worked flawlessly. 247 00:12:09.039 --> 00:12:11.679 It was a perfectly engineered piece of hardware, or so 248 00:12:11.799 --> 00:12:13.000 it seemed exactly. 249 00:12:13.039 --> 00:12:15.159 It was only when an engineer decided to design this 250 00:12:15.279 --> 00:12:19.120 extreme thermal shock test that the ghost finally revealed itself. 251 00:12:19.159 --> 00:12:20.559 Okay, tell me about this test. 252 00:12:20.759 --> 00:12:23.879 They froze the internal servo valve to simulate the freezing 253 00:12:23.879 --> 00:12:27.360 temperatures of high altitude cruising, and then suddenly blasted it 254 00:12:27.399 --> 00:12:31.080 with superheated hydraulic fluid, which simulated the heat generated as 255 00:12:31.120 --> 00:12:33.360 the pilots used the rudder during descent. 256 00:12:33.480 --> 00:12:37.159 And because of the extreme temperature difference, the microscopic metal 257 00:12:37.159 --> 00:12:40.879 components inside the valve expanded at different rates, so it jammed. 258 00:12:41.000 --> 00:12:43.799 Not only did it jam, but the internal flight moved 259 00:12:43.840 --> 00:12:47.399 just a fraction of a millimeter out of alignment. An 260 00:12:47.440 --> 00:12:50.799 engineer looking at the hydraulic pressure data realized that the 261 00:12:50.879 --> 00:12:53.919 valve didn't just lock up, it actually reversed its function. 262 00:12:54.159 --> 00:12:57.639 Okay, so imagine you were driving seventy miles per hour 263 00:12:57.679 --> 00:13:00.879 on the highway. You see a pothole, so you naturally 264 00:13:00.879 --> 00:13:03.080 turn your steering wheel to the right to avoid it. Right, 265 00:13:03.440 --> 00:13:07.120 But a microscopic mechanical glitch inside your steering column takes 266 00:13:07.159 --> 00:13:11.000 your right word movement, reverses the hydrault flow and violently 267 00:13:11.039 --> 00:13:14.080 swerves the car to the left, straight into a concrete wall. 268 00:13:14.399 --> 00:13:17.480 That is exactly what the dual servvalve did to those pilots. 269 00:13:17.759 --> 00:13:18.519 Unbelievable. 270 00:13:18.759 --> 00:13:21.159 When the plane started tilting left due to a gust 271 00:13:21.200 --> 00:13:23.519 of wind, they pushed the right pedal to correct it 272 00:13:23.600 --> 00:13:26.279 like they were trained to do, but the reverse valve 273 00:13:26.320 --> 00:13:29.200 took their input and sent the rudder hard left instead. 274 00:13:29.559 --> 00:13:31.440 So the harder they thought to save the plane, the 275 00:13:31.480 --> 00:13:34.000 harder the plane drove itself into the ground. They were 276 00:13:34.039 --> 00:13:35.200 completely helpless. 277 00:13:35.399 --> 00:13:38.480 It is a chilling realization. But because of that thermal 278 00:13:38.559 --> 00:13:43.960 shock discovery, Boeing spent hundreds of millions of dollars entirely 279 00:13:44.159 --> 00:13:47.759 redesigning and replacing the servo valves on thousands of seven 280 00:13:47.840 --> 00:13:50.879 hundred and thirty seven's worldwide. 281 00:13:50.240 --> 00:13:52.879 And they added a secondary override system so a jam 282 00:13:52.919 --> 00:13:55.919 could never dictate the flight path again exactly. So we've 283 00:13:55.919 --> 00:13:59.080 seen ghosts inside the machine itself. But what about the 284 00:13:59.279 --> 00:14:02.519 massive in visible systems guiding the machines. 285 00:14:02.080 --> 00:14:04.600 From the ground, the air traffic control systems. 286 00:14:04.720 --> 00:14:08.159 Yeah, let's shift our focus to August nineteen eighty six, 287 00:14:08.720 --> 00:14:12.559 a beautiful, crystal clear Labor Day weekend in Los Angeles 288 00:14:13.000 --> 00:14:15.320 air in Mexico. Flight four ninety eight, a DC nine 289 00:14:15.360 --> 00:14:17.759 is descending toward Los Angeles International Airport. 290 00:14:17.960 --> 00:14:20.879 Meanwhile, a man named William Kramer is flying his family 291 00:14:20.919 --> 00:14:23.159 in a small private Piper Cherokee. 292 00:14:23.200 --> 00:14:25.159 And he's a relatively new pilot. 293 00:14:24.840 --> 00:14:27.879 Right, Yeah, he's unfamiliar with the area, he's lost, and 294 00:14:27.919 --> 00:14:30.519 he's navigating by basically just looking out the window following 295 00:14:30.519 --> 00:14:31.759 the freeways below him. 296 00:14:31.639 --> 00:14:35.240 And without realizing it, he wanders straight into LAX's highly 297 00:14:35.240 --> 00:14:36.240 restricted airspace. 298 00:14:36.360 --> 00:14:38.559 Now down on the ground in a dark radar room, 299 00:14:38.600 --> 00:14:40.720 you have an air traffic controller named Walter. 300 00:14:40.519 --> 00:14:43.039 White, not the one from the TV show right. 301 00:14:43.000 --> 00:14:46.639 No, But he's managing a highly complex sequence of massive 302 00:14:46.639 --> 00:14:51.480 commercial arrivals. But his attention gets diverted by yet another 303 00:14:51.519 --> 00:14:55.120 private plane, a Grumman Tiger that has also blundered into 304 00:14:55.159 --> 00:14:56.919 his airspace unannounced. 305 00:14:57.200 --> 00:14:59.480 So while he's distracted talking to the Grumman trying to 306 00:14:59.480 --> 00:15:01.120 get it out of the way of the heavy jets, 307 00:15:01.200 --> 00:15:04.639 the Piper Cherokee and the Aero Mexico DC nine physically 308 00:15:04.679 --> 00:15:08.720 collide mid air over a suburban neighborhood in Cerritos. 309 00:15:08.799 --> 00:15:09.639 It's just terrific. 310 00:15:09.919 --> 00:15:14.559 The Piper slices the jet's horizontal stabilizer completely off. Eighty 311 00:15:14.600 --> 00:15:18.240 two people die, including fifteen innocent people on the ground. 312 00:15:18.879 --> 00:15:21.840 Entire houses were wiped off the map by the falling wreckage. 313 00:15:21.919 --> 00:15:24.559 It is a catastrophic failure of the air traffic system. 314 00:15:24.759 --> 00:15:27.279 But the most haunting question is how on Earth did 315 00:15:27.279 --> 00:15:30.080 the controller not see the Piper Cherokee on his radar 316 00:15:30.120 --> 00:15:31.559 screen heading straight for the jet. 317 00:15:31.759 --> 00:15:35.799 Well, that crash really exposed the tragic, fatal limitations of 318 00:15:35.840 --> 00:15:39.360 the technology at the time. The analog radar system suffered 319 00:15:39.360 --> 00:15:42.399 from something called flicker good flicker. Yeah, if the ancient 320 00:15:42.399 --> 00:15:45.759 computers got overloaded with data, secondary targets would simply drop 321 00:15:45.840 --> 00:15:47.360 off the screen for a sweep or two of the 322 00:15:47.440 --> 00:15:48.000 radar arms. 323 00:15:48.039 --> 00:15:48.960 So it just vanished. 324 00:15:49.320 --> 00:15:53.840 Yes. Furthermore, the piper's transponder was really basic. It was 325 00:15:53.879 --> 00:15:57.320 a mode A, meaning it only broadcast its position, not 326 00:15:57.480 --> 00:16:00.240 its altitude. Ah, so even if it popped up on 327 00:16:00.240 --> 00:16:03.320 the controllers screen, it was just this two dimensional blip 328 00:16:03.480 --> 00:16:06.919 with no height data flashing on and off right at 329 00:16:06.960 --> 00:16:10.440 the exact moment he was fixated on another rogue plane. 330 00:16:10.600 --> 00:16:13.759 But wait, it was a perfectly clear sunny day in 331 00:16:13.879 --> 00:16:18.279 southern California. Even if the radar was glitchy, Why didn't 332 00:16:18.279 --> 00:16:20.559 the pilots just look out the window and avoid each other? 333 00:16:20.559 --> 00:16:23.120 I mean, the rules of the sky dictate see and avoid. 334 00:16:23.279 --> 00:16:25.360 Well, see and avoid is a concept from the era 335 00:16:25.440 --> 00:16:28.759 of biplanes, and Serrita's proved it has fundamentally flawed at. 336 00:16:28.720 --> 00:16:31.960 Jet speeds because things are moving too fast exactly. 337 00:16:31.840 --> 00:16:34.639 It comes down to the strict biological limits of human eyesight. 338 00:16:35.039 --> 00:16:37.720 Studies conducted after the crash proved that a pilot needs 339 00:16:37.720 --> 00:16:40.480 a minimum of twelve seconds to spot an approaching aircraft, 340 00:16:40.840 --> 00:16:43.799 physically focus their eyes on it, recognize it as a 341 00:16:43.799 --> 00:16:47.399 collision thread, decide on an evasive maneuver, physically move the 342 00:16:47.399 --> 00:16:49.759 flight controls, and then wait for the inertia of a 343 00:16:49.799 --> 00:16:51.600 massive jet to actually change direction. 344 00:16:51.879 --> 00:16:53.679 Twelve seconds at three hundred miles an hour is an 345 00:16:53.720 --> 00:16:54.639 absolute eternity. 346 00:16:54.840 --> 00:16:57.759 It really is. Because the piper Cherokee was so small. 347 00:16:58.039 --> 00:16:59.840 By the time it was physically large enough in the 348 00:16:59.879 --> 00:17:03.480 DC nine's windshield to trigger a visual reaction, they were 349 00:17:03.600 --> 00:17:05.599 well passed that twelve second window. 350 00:17:05.799 --> 00:17:08.799 You literally biologically cannot react fast enough. 351 00:17:08.880 --> 00:17:11.160 The human eye is just not designed to prevent mid 352 00:17:11.200 --> 00:17:12.480 air collisions at jet. 353 00:17:12.400 --> 00:17:16.559 Speeds, and that realization completely transformed the airspace we fly 354 00:17:16.680 --> 00:17:21.079 in today. Congress actually stepped in and mandated a system 355 00:17:21.160 --> 00:17:25.880 called TCAs the Traffic Collision Avoidance System, which is brilliant Today. 356 00:17:26.319 --> 00:17:31.359 Every commercial jet is constantly invisibly broadcasting its position, speed, 357 00:17:31.400 --> 00:17:34.400 and altitude, communicating directly with the planes around it. 358 00:17:34.599 --> 00:17:37.960 Right, So if two planes get dangerously close. The computers 359 00:17:38.000 --> 00:17:40.200 bypass the air traffic controllers entirely. 360 00:17:40.319 --> 00:17:42.880 They talk to each other, and they issue loud voice 361 00:17:42.880 --> 00:17:45.960 commands directly into the pilot's headsets. One plane is commanded 362 00:17:46.000 --> 00:17:48.039 to climb, the other is commanded to descend. 363 00:17:48.200 --> 00:17:51.079 It takes the flawed human reaction time completely out of 364 00:17:51.079 --> 00:17:51.920 the equation. 365 00:17:51.799 --> 00:17:55.640 Which highlights a profound truth in accident investigation. You can 366 00:17:55.720 --> 00:17:58.680 engineer out the mechanical flaws, you can build flawless radar, 367 00:17:58.839 --> 00:18:00.359 you can invent TCA. 368 00:18:00.720 --> 00:18:03.599 But there is one variable in the cockpit that can 369 00:18:03.680 --> 00:18:06.240 never be fully engineered, updated, or patched. 370 00:18:06.319 --> 00:18:07.119 The human mind. 371 00:18:07.200 --> 00:18:10.839 The human element is, without a doubt, the most complex, 372 00:18:11.160 --> 00:18:13.480 unpredictable system on any aircraft. 373 00:18:13.640 --> 00:18:17.079 Let's talk about August nineteen ninety seven. Korean air flight 374 00:18:17.160 --> 00:18:19.599 eight oh one is on final approach to the island 375 00:18:19.599 --> 00:18:22.319 of Guam. It's well past midnight, and it. 376 00:18:22.319 --> 00:18:24.519 Is pouring rain, terrible conditions. 377 00:18:24.599 --> 00:18:26.920 Captain Park is a highly decorated pilot, but he is 378 00:18:27.039 --> 00:18:31.119 running on fumes. He is deeply fatigued. To make matters worse, 379 00:18:31.319 --> 00:18:35.119 the airport's electronic glide slope, the invisible radio beam that 380 00:18:35.160 --> 00:18:37.920 guides planes vertically down to the runway, is out of 381 00:18:37.960 --> 00:18:39.400 service for routine maintenance. 382 00:18:39.759 --> 00:18:43.119 So they are essentially flying a non precision approach blind 383 00:18:43.279 --> 00:18:47.319 in a tropical storm, relying entirely on altitude charts and timing. 384 00:18:47.039 --> 00:18:48.920 Which leaves very little room for error. 385 00:18:49.200 --> 00:18:52.319 Exactly. But there is a massive systemic failure lurking in 386 00:18:52.319 --> 00:18:54.599 the background here, well is it? The airport had a 387 00:18:54.599 --> 00:18:58.839 Minimum Safe Altitude Warning System or MSAW. It's a radar 388 00:18:58.880 --> 00:19:00.920 safety net designed to layer an alarm at the air 389 00:19:00.960 --> 00:19:04.079 traffic controllers if a plane drops dangerously low toward the. 390 00:19:04.119 --> 00:19:06.279 Terrain right to warn them they're about to hit a mountain. 391 00:19:06.480 --> 00:19:11.039 But the Federal Aviation Administration, the FAA, had deliberately moved 392 00:19:11.079 --> 00:19:14.079 the system's tracking zone eighty kilometers out to sea. 393 00:19:14.359 --> 00:19:16.559 Okay. I remember reading this in the report and thinking 394 00:19:16.559 --> 00:19:20.039 it was a typo. Why on Earth had an aviation 395 00:19:20.160 --> 00:19:23.599 authority take a safety net designed to protect mountains and 396 00:19:23.680 --> 00:19:25.599 move it out over the empty ocean. 397 00:19:25.720 --> 00:19:28.680 It's a psychological phenomenon called alarm fatigue. 398 00:19:29.039 --> 00:19:31.480 Oh, like when a car alarm goes off so much 399 00:19:31.480 --> 00:19:32.200 you just ignore it. 400 00:19:32.359 --> 00:19:36.039 Exactly. The MSIW alarms kept going off for planes that 401 00:19:36.079 --> 00:19:38.920