1 00:00:01,620 --> 00:00:04,413 Just minutes from Strasbourg Airport... - Merde! 2 00:00:04,482 --> 00:00:08,413 ...an Airbus A320 slams into a mountaintop. 3 00:00:15,793 --> 00:00:17,724 Delta Alpha, your position? 4 00:00:17,793 --> 00:00:19,206 There are survivors. 5 00:00:19,275 --> 00:00:21,689 And I panicked because I'm going to burn. 6 00:00:23,655 --> 00:00:26,551 But they are still in grave danger. 7 00:00:26,620 --> 00:00:28,344 It's bitterly cold, 8 00:00:28,413 --> 00:00:32,448 and what they don't realize is that no one knows where they are. 9 00:00:32,517 --> 00:00:34,965 They could be anywhere in there. 10 00:00:36,344 --> 00:00:40,275 We can expect this in the jungle or the rainforest, 11 00:00:40,344 --> 00:00:41,896 but not in a... 12 00:00:41,965 --> 00:00:44,000 highly populated area. 13 00:00:44,862 --> 00:00:47,068 Before investigators can begin searching 14 00:00:47,137 --> 00:00:50,517 for what caused the crash of Air Inter Flight 148... 15 00:00:54,620 --> 00:00:56,620 ...they must first find the plane. 16 00:01:03,275 --> 00:01:05,482 Mayday, mayday. 17 00:01:27,655 --> 00:01:30,137 January the 20th, 1992. 18 00:01:34,103 --> 00:01:38,000 Air Inter Flight 148 has departed from Lyon, France. 19 00:01:40,034 --> 00:01:42,206 124.95, thank you. 20 00:01:45,000 --> 00:01:47,068 Captain Christian Hecquet... 21 00:01:47,137 --> 00:01:50,103 and First Officer Joel Cherubin are experienced pilots 22 00:01:50,172 --> 00:01:53,586 with over 12,000 hours of flying time between them. 23 00:01:56,275 --> 00:02:00,482 The flight is a short hop between Lyon, in central France, 24 00:02:00,551 --> 00:02:03,965 and the city of Strasbourg, in the mountainous Alsace region. 25 00:02:06,827 --> 00:02:10,931 The French airline Air Inter caters mostly to business travellers 26 00:02:11,000 --> 00:02:13,310 and prides itself on being timely. 27 00:02:15,310 --> 00:02:17,862 Crews are motivated to avoid delays, 28 00:02:17,931 --> 00:02:21,413 as former Air Inter pilot Gerard Arnoux explains. 29 00:02:22,310 --> 00:02:25,241 We were famous for our very short turnaround. 30 00:02:26,172 --> 00:02:28,620 And the faster we flew, 31 00:02:28,689 --> 00:02:31,172 the better wages we got. 32 00:02:34,137 --> 00:02:36,482 Have we been flying for 35 minutes yet? 33 00:02:37,793 --> 00:02:39,482 Forty-one minutes. 34 00:02:44,862 --> 00:02:47,724 The crew is flying an Airbus A320, 35 00:02:47,793 --> 00:02:51,724 one of the most technologically advanced commercial airplanes in the world. 36 00:02:51,793 --> 00:02:53,482 Even before takeoff, 37 00:02:53,551 --> 00:02:55,758 the pilots programmed the autopilot to land 38 00:02:55,827 --> 00:02:57,931 on a specific runway in Strasbourg. 39 00:03:00,965 --> 00:03:04,551 The cockpit of the A320 is also very different from other planes. 40 00:03:05,172 --> 00:03:06,965 Instead of analog gauges, 41 00:03:07,034 --> 00:03:09,620 the pilots look mostly at digital displays. 42 00:03:14,724 --> 00:03:16,551 Strasbourg, good evening. 43 00:03:16,620 --> 00:03:18,551 Runway in use: 05. 44 00:03:19,103 --> 00:03:20,862 Transition level: 50. 45 00:03:21,448 --> 00:03:24,068 040, at 18 knots, 46 00:03:24,275 --> 00:03:26,000 visibility: 10 kilometres. 47 00:03:26,068 --> 00:03:28,551 A recording from Strasbourg Airport 48 00:03:28,620 --> 00:03:31,034 informs the crew of a change in plan. 49 00:03:31,724 --> 00:03:34,586 Due to high winds and poor winter weather, 50 00:03:34,655 --> 00:03:37,034 they'll have to land on an alternate runway... 51 00:03:38,413 --> 00:03:40,172 05 in service. 52 00:03:40,827 --> 00:03:44,137 ...not the one programmed into the autopilot. 53 00:03:44,206 --> 00:03:47,931 05? What sort of wind are they giving us? 54 00:03:48,000 --> 00:03:49,862 Eighteen knots. 55 00:03:50,586 --> 00:03:52,862 Eighteen knots. 56 00:03:54,379 --> 00:03:57,620 Captain Hecquet doesn't like the idea of changing runways. 57 00:03:58,482 --> 00:04:00,068 No chance. 58 00:04:00,827 --> 00:04:03,758 He was hoping to use Runway 23, 59 00:04:03,827 --> 00:04:08,000 an approach that provides the autopilot with a precise navigational fix. 60 00:04:09,931 --> 00:04:12,827 The new runway, Runway 05, 61 00:04:12,896 --> 00:04:15,000 is surrounded by mountainous terrain 62 00:04:15,068 --> 00:04:18,034 that can interrupt radio signals sent to the autopilot. 63 00:04:21,689 --> 00:04:26,137 You know, if we go with the Runway 05 procedure, we... 64 00:04:26,206 --> 00:04:27,896 Well, no. Ahem. 65 00:04:29,034 --> 00:04:31,758 Captain Hecquet suggests a compromise. 66 00:04:31,827 --> 00:04:33,896 I'm putting back Runway 23. 67 00:04:33,965 --> 00:04:36,620 Otherwise, I couldn't make the ILS interception. 68 00:04:38,551 --> 00:04:42,068 He'll program the autopilot to fly towards Runway 23. 69 00:04:43,689 --> 00:04:45,206 But near the airport, 70 00:04:45,275 --> 00:04:47,379 the captain will take over the controls 71 00:04:47,448 --> 00:04:50,103 and make a visual landing on Runway 05. 72 00:04:52,275 --> 00:04:53,965 You're taking 23, then? 73 00:04:54,034 --> 00:04:55,448 Yes! 74 00:04:57,586 --> 00:04:58,862 Agreed. 75 00:05:01,137 --> 00:05:04,172 Ladies and gentlemen, we are commencing our descent. 76 00:05:04,241 --> 00:05:05,724 We ask you to please... 77 00:05:05,793 --> 00:05:08,655 Nicolas Skourias is a university graduate student. 78 00:05:11,862 --> 00:05:14,310 It was a... quiet day. 79 00:05:14,379 --> 00:05:16,655 I was, uh... 80 00:05:16,724 --> 00:05:20,379 expecting to go to see my girlfriend in Strasbourg. 81 00:05:20,448 --> 00:05:22,000 So I was very happy. 82 00:05:24,517 --> 00:05:28,862 Roger 854, proceed to GTQ. Air level: 140. Contact Reims. 83 00:05:31,034 --> 00:05:32,793 Delta Alpha, Strasbourg. 84 00:05:32,862 --> 00:05:37,931 Uh, yes, we intend to proceed to do an ILS on Runway 23, 85 00:05:38,000 --> 00:05:41,275 uh, then an indirect for Runway 05 after that. 86 00:05:43,172 --> 00:05:46,206 The Strasbourg controller considers the captain's plan. 87 00:05:46,275 --> 00:05:47,965 Delta Alpha. 88 00:05:48,034 --> 00:05:51,551 He warns that there will likely be a delay due to heavy traffic. 89 00:05:51,620 --> 00:05:54,206 Given that we're going to have three takeoffs on 05, 90 00:05:54,275 --> 00:05:56,137 you risk waiting in a stack at 5,000 feet. 91 00:05:56,206 --> 00:05:58,827 We're not going to mess about like that, descending at full speed. 92 00:06:00,965 --> 00:06:04,310 If they had warned us in advance! Cripes! 93 00:06:07,172 --> 00:06:08,862 Delta Alpha, Strasbourg. 94 00:06:08,931 --> 00:06:11,965 I hear you. Aware of the captain's frustration, 95 00:06:12,034 --> 00:06:13,931 the controller offers assistance. 96 00:06:14,551 --> 00:06:19,000 If you want, I can take you with the radar to lead you to ANDLO at 5,000. 97 00:06:19,068 --> 00:06:22,655 ANDLO is a navigational point on the approach to Runway 05. 98 00:06:22,724 --> 00:06:25,275 It helps pilots align the plane for landing. 99 00:06:26,413 --> 00:06:27,827 Yeah, that's good. 100 00:06:27,896 --> 00:06:29,344 Oh, yeah. 101 00:06:29,413 --> 00:06:33,172 Okay, then, turn left to heading 230 degrees. 102 00:06:33,241 --> 00:06:36,620 148, turn left to heading... 103 00:06:36,689 --> 00:06:38,551 230 degrees. 104 00:06:38,620 --> 00:06:41,413 There you are. That will save you some time. 105 00:06:44,620 --> 00:06:49,310 Since Runway 05 doesn't allow for a full autopilot approach, 106 00:06:49,379 --> 00:06:52,793 the captain must calculate the angle of descent on his own. 107 00:06:54,275 --> 00:06:55,689 That makes... 108 00:06:55,758 --> 00:06:57,862 3.3 degrees. 109 00:07:06,241 --> 00:07:08,758 3.3 degrees is a normal flight angle 110 00:07:08,827 --> 00:07:10,896 that provides a good slope for landing. 111 00:07:15,620 --> 00:07:18,724 Ladies and gentlemen, we are continuing our descent... 112 00:07:18,793 --> 00:07:22,034 The flight from Lyon to Strasbourg was quite short. 113 00:07:22,103 --> 00:07:24,241 I think 50 or 45 minutes, 114 00:07:24,310 --> 00:07:25,862 nothing special. 115 00:07:25,931 --> 00:07:28,655 It was, uh, very natural and very ordinary. 116 00:07:28,724 --> 00:07:30,137 Thank you. 117 00:07:32,827 --> 00:07:35,310 Turn left, steer 90. 118 00:07:39,482 --> 00:07:41,827 Zero-niner degrees, Delta Alpha. 119 00:07:42,344 --> 00:07:45,689 The controller talks Flight 148 through the last turn 120 00:07:45,758 --> 00:07:47,655 to align the plane with the runway, 121 00:07:47,724 --> 00:07:49,482 now 25 kilometres away. 122 00:07:51,862 --> 00:07:55,793 Then First Officer Cherubin notices the plane is slightly off course. 123 00:07:58,241 --> 00:07:59,931 You are headed inside. 124 00:08:00,827 --> 00:08:02,310 You're inside there. 125 00:08:02,379 --> 00:08:04,379 You should've started with 070. 126 00:08:04,448 --> 00:08:06,000 Yeah. 127 00:08:09,689 --> 00:08:11,965 - At least that much. - Ahem. 128 00:08:14,655 --> 00:08:19,068 The controller also notices that the plane is off course. 129 00:08:19,137 --> 00:08:21,034 Air Inter Delta Alpha. 130 00:08:21,103 --> 00:08:23,620 It has missed aligning itself with ANDLO, 131 00:08:23,689 --> 00:08:25,862 the runway's electronic guidepost. 132 00:08:27,551 --> 00:08:30,413 Delta Alpha, you're passing to the right of ANDLO. 133 00:08:32,206 --> 00:08:35,103 Nevertheless, he authorizes the landing. 134 00:08:35,965 --> 00:08:38,551 Authorized for final approach, 05. 135 00:08:40,896 --> 00:08:42,517 Delta Alpha. 136 00:08:42,586 --> 00:08:45,586 The captain initiates the landing sequence. 137 00:08:45,655 --> 00:08:48,275 - Flaps towards 2. - Flaps towards 2. 138 00:08:50,517 --> 00:08:51,827 Flaps at 2. 139 00:08:51,896 --> 00:08:53,206 Gear down. 140 00:08:59,655 --> 00:09:02,620 Ladies and gentlemen, we are going to land in a few minutes. 141 00:09:06,206 --> 00:09:09,586 Hecquet notices that the plane is travelling too fast, 142 00:09:09,655 --> 00:09:11,310 so he extends the speed brakes. 143 00:09:11,379 --> 00:09:13,827 They disrupt airflow over the wing, 144 00:09:13,896 --> 00:09:17,034 which helps create more drag to slow the plane. 145 00:09:17,103 --> 00:09:18,758 We have to watch our descent. 146 00:09:20,310 --> 00:09:23,241 The approach axis... The first officer is more concerned 147 00:09:23,310 --> 00:09:26,758 with their horizontal position in relation to the runway. 148 00:09:26,827 --> 00:09:28,965 - It was 60. Check it out. - Oui, oui. 149 00:09:30,482 --> 00:09:33,551 But before the crew can adjust their course... 150 00:09:35,034 --> 00:09:37,517 Merde! 151 00:09:52,103 --> 00:09:55,068 Delta Alpha, your position? 152 00:09:55,655 --> 00:09:57,482 Air Inter Delta Alpha, Strasbourg. 153 00:10:03,275 --> 00:10:05,758 The crash is catastrophic. 154 00:10:05,827 --> 00:10:09,000 The A320 has flown into the side of a mountain. 155 00:10:13,620 --> 00:10:15,103 Delta Alpha, your position? 156 00:10:16,379 --> 00:10:19,103 Flight 148 is no longer on radar... 157 00:10:20,517 --> 00:10:22,724 ...nor responding to radio contact. 158 00:10:23,620 --> 00:10:26,172 An emergency is declared at Strasbourg Airport. 159 00:10:27,965 --> 00:10:32,241 This is the last hit we got. They were flying 20 kilometres away from the airport. 160 00:10:33,482 --> 00:10:36,068 Officials need to pinpoint the crash site. 161 00:10:36,137 --> 00:10:38,482 But it's not as easy as it might seem. 162 00:10:38,551 --> 00:10:40,827 The airport's radar is not recorded. 163 00:10:40,896 --> 00:10:43,896 There has been no signal from the plane's emergency beacon. 164 00:10:43,965 --> 00:10:45,551 And, surprisingly, 165 00:10:45,620 --> 00:10:48,103 no one has reported seeing a plane go down. 166 00:10:50,413 --> 00:10:52,379 It could be anywhere in here. 167 00:10:53,172 --> 00:10:56,689 The proposed search area covers more than 20 square kilometres 168 00:10:56,758 --> 00:10:59,275 of dense forest just outside Strasbourg. 169 00:11:11,482 --> 00:11:15,413 Nicolas Skourias survives the crash of Air Inter Flight 148 170 00:11:15,482 --> 00:11:17,586 with only minor injuries. 171 00:11:21,793 --> 00:11:25,310 I took off my, uh, seatbelt. I get up. 172 00:11:25,379 --> 00:11:28,793 I tried to find my, uh, suitcase, uh... 173 00:11:28,862 --> 00:11:30,310 in the lockers, 174 00:11:30,379 --> 00:11:31,931 but, uh... 175 00:11:32,000 --> 00:11:34,000 there wasn't any lockers. 176 00:11:35,068 --> 00:11:37,758 I realized that I was alive; it was a crash. 177 00:11:37,827 --> 00:11:41,137 I saw fire in front of me and I panicked, 178 00:11:41,206 --> 00:11:44,344 because I say to myself: I'm going to burn. 179 00:11:47,034 --> 00:11:50,862 I went to the back of the plane, what remained of the plane... 180 00:11:56,172 --> 00:11:57,689 I found some other survivors. 181 00:11:57,758 --> 00:11:59,517 Come on! 182 00:11:59,586 --> 00:12:01,310 It's gonna blow! 183 00:12:01,379 --> 00:12:04,482 I was afraid of the explosion. I was a panic. 184 00:12:04,551 --> 00:12:07,517 With the smell of leaking jet fuel in the air, 185 00:12:07,586 --> 00:12:10,172 the survivors move away from the burning plane. 186 00:12:14,758 --> 00:12:16,310 We stayed together, 187 00:12:16,379 --> 00:12:18,724 waiting for the first aid. 188 00:12:18,793 --> 00:12:22,034 But the wait will be longer than anyone might expect. 189 00:12:25,103 --> 00:12:28,655 The first reaction that we have after the crash was: 190 00:12:28,724 --> 00:12:31,931 Okay, in half an hour, 191 00:12:32,000 --> 00:12:33,827 one hour... 192 00:12:33,896 --> 00:12:36,172 most and worst, 193 00:12:36,241 --> 00:12:38,724 okay, the rescue team will be here. 194 00:12:38,793 --> 00:12:40,482 And it wasn't here. 195 00:12:42,689 --> 00:12:44,551 One hour after the crash, 196 00:12:44,620 --> 00:12:48,206 rescuers still have no idea where the wreckage lies. 197 00:12:53,551 --> 00:12:56,551 Skourias and the others now face a new ordeal: 198 00:12:58,896 --> 00:13:03,482 Surviving sub-zero temperatures in a dark and isolated forest. 199 00:13:06,965 --> 00:13:10,275 Two-and-a-half hours after Flight 148 disappeared from radar 200 00:13:10,344 --> 00:13:11,827 near Strasbourg Airport... 201 00:13:14,344 --> 00:13:16,931 ...the missing plane has still not been located. 202 00:13:17,000 --> 00:13:18,517 Amidst growing tension, 203 00:13:18,586 --> 00:13:21,137 the French aviation bureau, the BEA, 204 00:13:21,206 --> 00:13:24,068 sends in its lead investigator, Jean Paries. 205 00:13:25,413 --> 00:13:29,344 I immediately called my two main investigators, 206 00:13:29,413 --> 00:13:31,896 and we organized the go team. 207 00:13:33,517 --> 00:13:36,068 And we got prepared to rush to the site 208 00:13:36,137 --> 00:13:39,275 as soon as this site was located somewhere. 209 00:13:39,344 --> 00:13:42,103 The delay feels like an eternity. 210 00:13:42,517 --> 00:13:44,586 A bit surprisingly long. 211 00:13:44,655 --> 00:13:48,206 We can expect this in the jungle or the rainforest, 212 00:13:48,275 --> 00:13:51,344 but not exactly in a... 213 00:13:51,413 --> 00:13:56,137 highly dense populated area like the Strasbourg area. 214 00:13:57,862 --> 00:13:59,965 With no help in sight, 215 00:14:00,034 --> 00:14:02,931 Skourias returns to the wreckage to look for more survivors. 216 00:14:05,034 --> 00:14:08,482 I think that some people that die, uh, 217 00:14:08,551 --> 00:14:13,000 could have survived if the first aid... had come sooner. 218 00:14:19,517 --> 00:14:22,517 Nearly 1,000 people search for the missing plane. 219 00:14:23,344 --> 00:14:26,620 But three hours after the crash, there's still no sign of it. 220 00:14:26,689 --> 00:14:29,896 Frustrated, Skourias goes looking for help. 221 00:14:31,034 --> 00:14:34,241 He stumbles into a TV crew trying to find the crash. 222 00:14:35,068 --> 00:14:38,517 But with no wreckage in sight, they react with skepticism. 223 00:14:38,586 --> 00:14:40,172 They didn't expect... 224 00:14:41,172 --> 00:14:43,655 ...uh, survivors from an airplane crash. 225 00:14:43,724 --> 00:14:46,758 Hey! Hey, you have to believe me! 226 00:14:46,827 --> 00:14:50,448 They didn't believe that I was one of... the survivors, 227 00:14:50,517 --> 00:14:52,103 but believe me, I was, 228 00:14:52,172 --> 00:14:54,551 because my face was black, uh, 229 00:14:54,620 --> 00:14:56,758 due to the smoke, 230 00:14:56,827 --> 00:14:58,241 the kerosene and so on. 231 00:14:58,310 --> 00:14:59,827 Come on! 232 00:14:59,896 --> 00:15:02,827 The journalists follow him back to the crash site... 233 00:15:04,620 --> 00:15:07,000 ...where they discover eight other survivors. 234 00:15:13,655 --> 00:15:17,241 Finally, the first rescuers arrive. 235 00:15:18,000 --> 00:15:22,689 The crash site is located near the top of the 2,500-foot Mont Ste. Odile... 236 00:15:23,655 --> 00:15:25,724 ...19 kilometres from the runway. 237 00:15:26,344 --> 00:15:27,896 They found us... 238 00:15:27,965 --> 00:15:31,793 after four hours and 30 minutes. 239 00:15:32,448 --> 00:15:34,482 So it was a mess. 240 00:15:34,551 --> 00:15:36,793 I was very, very disappointed 241 00:15:36,862 --> 00:15:41,000 that at 20 kilometres from Strasbourg and, uh... 242 00:15:41,068 --> 00:15:42,758 they couldn't find us. 243 00:15:44,275 --> 00:15:47,896 A total of 87 passengers and crew have died, 244 00:15:47,965 --> 00:15:50,344 including the pilot and co-pilot. 245 00:15:52,620 --> 00:15:54,241 The survivors begin to tell their stories, 246 00:15:54,310 --> 00:15:58,620 but no one reports anything that might explain why the plane crashed. 247 00:15:59,517 --> 00:16:01,137 I don't know what happened. 248 00:16:01,206 --> 00:16:05,344 We were landing, I lost all consciousness. We must've hit the trees. 249 00:16:10,103 --> 00:16:14,758 Bob MacIntosh, an American NTSB investigator, arrives at the crash site. 250 00:16:17,620 --> 00:16:19,482 The BEA of France, uh, 251 00:16:19,551 --> 00:16:22,896 recognized the international attention would be on this accident. 252 00:16:22,965 --> 00:16:24,586 Even though it was a domestic accident, 253 00:16:24,655 --> 00:16:28,827 he invited a group of international accident investigators, uh, 254 00:16:28,896 --> 00:16:30,655 to come and participate. 255 00:16:32,413 --> 00:16:34,517 Jean Paries. Welcome to the team. 256 00:16:34,586 --> 00:16:36,827 The first priority for investigators 257 00:16:36,896 --> 00:16:39,241 is to retrieve the plane's black boxes. 258 00:16:39,310 --> 00:16:42,241 We have not removed the recorders yet. 259 00:16:42,310 --> 00:16:46,137 With the boxes trapped in the burning tail section, 260 00:16:46,206 --> 00:16:48,206 any delay could prove costly. 261 00:16:50,344 --> 00:16:52,137 We were very anxious about... 262 00:16:52,206 --> 00:16:55,862 the state of the tape inside. 263 00:16:55,931 --> 00:16:58,034 Will it be possible to use it? 264 00:16:58,103 --> 00:17:01,206 Will we get the critical information we need? 265 00:17:02,344 --> 00:17:04,241 In France, 266 00:17:04,310 --> 00:17:07,827 aviation accidents are also investigated by the justice system. 267 00:17:07,896 --> 00:17:10,827 Paries and his team are not allowed access to the site 268 00:17:10,896 --> 00:17:13,724 until judicial officials secure the black boxes. 269 00:17:14,482 --> 00:17:17,965 I had a visual picture of the Gendarmes Aériennes, 270 00:17:18,034 --> 00:17:20,586 the transport police, standing around, 271 00:17:20,655 --> 00:17:23,517 keeping us away from the wreckage for a while. 272 00:17:25,275 --> 00:17:27,965 And were very suspicious of these international observers... 273 00:17:28,034 --> 00:17:30,620 - Maybe we should wait. - ...even taking photographs, 274 00:17:30,689 --> 00:17:33,517 which was somewhat surprising to us. 275 00:17:36,551 --> 00:17:41,482 In a previous crash, the crash of Air France Flight 296 in 1988, 276 00:17:41,551 --> 00:17:46,103 investigators waited 10 days before turning the black boxes over to police. 277 00:17:46,172 --> 00:17:49,137 Rumours persisted that these boxes had been tampered with. 278 00:17:51,793 --> 00:17:54,862 This time, police are keeping investigators at bay. 279 00:17:54,931 --> 00:17:57,241 I can recall seeing the glowing embers, 280 00:17:57,310 --> 00:18:01,448 and seeing the flight recorder sitting there and, uh... 281 00:18:01,517 --> 00:18:03,793 not being able to intervene and say, 282 00:18:03,862 --> 00:18:06,482 "Get that thing cooled down as soon as you can." 283 00:18:11,310 --> 00:18:15,448 After midnight, the boxes are retrieved from the plane and sent for analysis. 284 00:18:16,517 --> 00:18:19,413 Investigators can only hope it's not too late. 285 00:18:19,482 --> 00:18:21,241 They were extremely hot. 286 00:18:21,310 --> 00:18:23,931 They looked damaged, they looked burned. 287 00:18:29,862 --> 00:18:31,482 In the light of day, 288 00:18:31,551 --> 00:18:35,000 investigators get some of their first clues from the crash site itself. 289 00:18:35,896 --> 00:18:40,172 They discover why the plane's emergency locator beacon didn't send a signal. 290 00:18:41,103 --> 00:18:44,482 It was actually destroyed by the impact. 291 00:18:46,620 --> 00:18:49,000 The beacon is located inside the cockpit 292 00:18:49,068 --> 00:18:51,724 and is designed to start working after a crash. 293 00:18:52,482 --> 00:18:55,862 Its failure suggests an unusually forceful impact with the ground. 294 00:18:55,931 --> 00:18:58,068 We had this first feeling... 295 00:18:58,137 --> 00:19:00,448 the descent was abnormally steep. 296 00:19:01,586 --> 00:19:03,482 Investigators examine the engines 297 00:19:03,551 --> 00:19:05,896 to see if they may have stalled before impact. 298 00:19:07,482 --> 00:19:12,310 If you find the blades curved and a lot of wood, uh... 299 00:19:12,655 --> 00:19:15,000 ...sucked inside the engines, 300 00:19:15,068 --> 00:19:19,758 then you understand that the engines were working properly. 301 00:19:20,310 --> 00:19:22,413 And that's exactly what they find. 302 00:19:22,482 --> 00:19:24,413 The plane clearly had power, 303 00:19:24,482 --> 00:19:26,931 yet it plowed steeply into a mountainside 304 00:19:27,000 --> 00:19:29,206 without ever sending out a distress signal. 305 00:19:33,586 --> 00:19:35,172 Investigators are puzzled. 306 00:19:38,310 --> 00:19:41,000 They hope that the box which recorded the plane's flight data 307 00:19:41,068 --> 00:19:42,931 will help them solve the mystery. 308 00:19:46,689 --> 00:19:48,896 Those particular recorders... 309 00:19:48,965 --> 00:19:51,620 had the best survival record of any recorders. 310 00:19:51,689 --> 00:19:55,965 They were the top-of-the-line as far as survivability is concerned. 311 00:19:56,034 --> 00:19:58,896 The black box is designed to survive temperatures 312 00:19:58,965 --> 00:20:02,172 up to 1100° Celsius for half an hour. 313 00:20:03,620 --> 00:20:07,275 The tape recorder inside is protected by a capsule filled with water. 314 00:20:12,448 --> 00:20:15,758 When the recorder heats up, the water turns to steam, 315 00:20:15,827 --> 00:20:17,793 absorbing the energy, 316 00:20:17,862 --> 00:20:20,827 and actually vents out through a little hole in the crash enclosure. 317 00:20:21,827 --> 00:20:24,344 But when the flight-data recorder is opened, 318 00:20:24,413 --> 00:20:26,620 investigators make a troubling discovery. 319 00:20:28,862 --> 00:20:31,482 DFDR was totally damaged, 320 00:20:31,551 --> 00:20:34,413 impossible to read anything from it. 321 00:20:36,241 --> 00:20:39,241 It was subjected to heat beyond the 30 minutes. 322 00:20:39,310 --> 00:20:41,655 The recorder was just never designed 323 00:20:41,724 --> 00:20:44,793 to withstand that kind of sustained heat. 324 00:20:44,862 --> 00:20:47,655 And so we were very, uh, disappointed. 325 00:20:48,310 --> 00:20:49,931 There's now only one hope 326 00:20:50,000 --> 00:20:52,068 for recovering the plane's flight data, 327 00:20:52,137 --> 00:20:55,344 a device called a Quick Access Recorder, or QAR. 328 00:20:56,137 --> 00:20:59,896 Maintenance workers use the QAR to access the plane's computers, 329 00:20:59,965 --> 00:21:02,275 but it also records some flight data. 330 00:21:03,931 --> 00:21:07,586 Unlike the black boxes, the QAR is stored near the cockpit. 331 00:21:08,620 --> 00:21:10,827 The Quick Access Recorders are not protected at all. 332 00:21:10,896 --> 00:21:13,068 They're up in the front end of the aircraft, 333 00:21:13,137 --> 00:21:15,137 typically in the electronics bay. 334 00:21:15,206 --> 00:21:18,551 They're generally destroyed just from the impact damage. 335 00:21:19,206 --> 00:21:22,206 Investigators are encouraged to discover that in this case, 336 00:21:22,275 --> 00:21:24,068 the QAR has survived. 337 00:21:25,241 --> 00:21:27,103 But on closer examination, 338 00:21:27,172 --> 00:21:29,448 their optimism turns to frustration. 339 00:21:34,620 --> 00:21:39,000 The last 20 centimetres of the tape were burned and, uh... 340 00:21:39,068 --> 00:21:40,620 stretched, 341 00:21:40,689 --> 00:21:45,103 and were damaged to the point that we could not use them into a machine. 342 00:21:45,172 --> 00:21:46,724 We couldn't read it. 343 00:21:49,655 --> 00:21:52,551 Investigators are desperate to retrieve the data, 344 00:21:52,620 --> 00:21:55,620 so they take a chance on an experimental technique. 345 00:21:55,689 --> 00:21:57,344 Known as the "garnet technique," 346 00:21:57,413 --> 00:22:00,620 a light is shone through a mineral lens made of garnet. 347 00:22:04,275 --> 00:22:07,827 You use a garnet stone to visualize the magnetic pulses 348 00:22:07,896 --> 00:22:10,275 that are actually recorded on the tape. 349 00:22:10,344 --> 00:22:12,655 The special lens helps the technicians 350 00:22:12,724 --> 00:22:17,310 differentiate between the positive and negative magnetic pulses, 351 00:22:17,379 --> 00:22:19,758 which translate as binary digits, or bits. 352 00:22:20,862 --> 00:22:24,241 There's 768 bits per second, 353 00:22:24,310 --> 00:22:27,137 so that's a lot of ones and zeros. 354 00:22:27,965 --> 00:22:30,862 You have to be very precise in moving the tape 355 00:22:30,931 --> 00:22:33,068 under the lens or the garnet 356 00:22:33,137 --> 00:22:36,275 to make sure you don't miss a bit 357 00:22:36,344 --> 00:22:39,103 or read the same bit twice, you know? 358 00:22:39,172 --> 00:22:41,206 So it's difficult. 359 00:22:41,275 --> 00:22:44,275 Analyzing the data is even more painstaking. 360 00:22:46,034 --> 00:22:50,241 It took about a day to read a second of... 361 00:22:50,310 --> 00:22:52,103 recording. 362 00:22:52,172 --> 00:22:57,586 Any additional second recovered could reveal something that would make a difference. 363 00:22:58,517 --> 00:23:02,724 The effort to retrieve all the QAR data could take a month or more. 364 00:23:07,931 --> 00:23:09,620 In the meantime, 365 00:23:09,689 --> 00:23:13,275 the focus of the investigation shifts to the cockpit voice recorder. 366 00:23:14,965 --> 00:23:17,724 It was positioned just above the other black box. 367 00:23:18,724 --> 00:23:22,896 The cockpit voice recorder, which was just inches away, but outside of the ashes, 368 00:23:22,965 --> 00:23:27,000 had air passing over it... and survived. 369 00:23:27,068 --> 00:23:28,862 ...Runway 23. Otherwise... 370 00:23:28,931 --> 00:23:32,655 The recording reveals the captain's anxiety early on in the flight. 371 00:23:33,586 --> 00:23:35,482 - You're taking 23, then? - Yes! 372 00:23:37,379 --> 00:23:40,379 Investigators know that landing on Runway 05 373 00:23:40,448 --> 00:23:43,137 requires what's called a non-precision approach. 374 00:23:43,965 --> 00:23:46,344 That means pilots receive electronic guidance 375 00:23:46,413 --> 00:23:48,586 only on their horizontal position: 376 00:23:48,655 --> 00:23:50,137 left and right. 377 00:23:50,206 --> 00:23:52,620 They get no guidance when it comes to altitude. 378 00:23:54,448 --> 00:23:58,310 The non-precision approach is significantly less accurate. 379 00:23:58,379 --> 00:24:01,551 It's not really difficult, but they are less comfortable. 380 00:24:01,620 --> 00:24:03,344 05? 381 00:24:04,379 --> 00:24:07,034 What sort of wind are they giving us? 382 00:24:08,172 --> 00:24:11,724 The non-precision approach increases the demands on the pilots. 383 00:24:11,793 --> 00:24:14,827 Investigators can also hear that the captain had concerns 384 00:24:14,896 --> 00:24:17,103 about landing on Runway 05. 385 00:24:21,310 --> 00:24:25,827 Forty-eight, Delta Alpha, you are number one for VOR/DME, Runway 05. 386 00:24:29,413 --> 00:24:31,482 Runway 05, 05. 387 00:24:32,655 --> 00:24:35,310 Ten nautical. That won't work. 388 00:24:36,517 --> 00:24:39,000 That's a lot of distress over a non-precision approach. 389 00:24:41,034 --> 00:24:43,448 Wondering what can cause such distress, 390 00:24:43,517 --> 00:24:46,551 investigators research pilot training at Air Inter. 391 00:24:46,620 --> 00:24:49,758 They find that most pilots did not have extensive training 392 00:24:49,827 --> 00:24:53,000 making non-precision landings in the new A320. 393 00:24:55,862 --> 00:24:59,103 I think we should've had double the training 394 00:24:59,172 --> 00:25:01,000 compared to an older plane. 395 00:25:01,655 --> 00:25:04,103 Investigators ask the airline for detailed records 396 00:25:04,172 --> 00:25:06,862 on the pilot's history of runway approaches. 397 00:25:11,586 --> 00:25:13,758 They're intrigued by what they discover. 398 00:25:16,586 --> 00:25:20,103 Captain Hecquet had landed at Strasbourg countless times, 399 00:25:20,172 --> 00:25:22,689 but he had never landed an A320 there 400 00:25:22,758 --> 00:25:24,586 using a non-precision approach. 401 00:25:26,172 --> 00:25:29,827 We're not going to mess around like that descending at full speed. 402 00:25:30,448 --> 00:25:32,137 Clearly the captain was uneasy 403 00:25:32,206 --> 00:25:35,448 about having to execute a landing he had never made before. 404 00:25:37,172 --> 00:25:39,413 I think the captain was worried about making it in, 405 00:25:39,482 --> 00:25:42,137 in a minimum amount of time, in the minimum amount of delay. 406 00:25:42,206 --> 00:25:45,379 Have we been flying for 35 minutes yet? 407 00:25:46,724 --> 00:25:50,758 And the co-pilot was worried about not getting in trouble by offending the captain. 408 00:25:50,827 --> 00:25:52,413 At least that much. 409 00:25:53,241 --> 00:25:57,344 More research into the pilot's work history offers yet another revelation. 410 00:25:58,620 --> 00:26:02,724 While the two pilots had flown more than 12,000 hours between them, 411 00:26:02,793 --> 00:26:07,275 they were both still relatively new to the highly advanced A320. 412 00:26:07,344 --> 00:26:09,000 It's 05 in service. 413 00:26:09,068 --> 00:26:12,000 The aviation community misunderstood... 414 00:26:12,068 --> 00:26:16,931 the magnitude of changes brought by the new Airbus A320. 415 00:26:18,310 --> 00:26:22,448 The captain had only 162 hours in the A320. 416 00:26:23,931 --> 00:26:25,827 And the co-pilot, even less. 417 00:26:25,896 --> 00:26:27,931 Just 61 hours. 418 00:26:31,172 --> 00:26:32,931 Behind this accident scenario, 419 00:26:33,000 --> 00:26:35,517 there is an issue of confidence... 420 00:26:36,137 --> 00:26:38,758 ...of the crew in themselves, 421 00:26:38,827 --> 00:26:40,448 in the aircraft. 422 00:26:41,586 --> 00:26:43,275 Eighteen knots. 423 00:26:43,344 --> 00:26:44,827 No chance. 424 00:26:44,896 --> 00:26:48,931 They were not prepared, really, to fly in, uh, this kind of condition. 425 00:26:49,000 --> 00:26:51,931 If they had warned us in advance. Cripes! 426 00:26:56,965 --> 00:27:00,275 Investigators conclude that the crew's training was insufficient. 427 00:27:00,965 --> 00:27:04,172 But that alone does not explain the crash. 428 00:27:04,793 --> 00:27:06,000 Merde! 429 00:27:15,206 --> 00:27:19,137 Investigators search for other factors in the crash of Flight 148. 430 00:27:19,206 --> 00:27:22,724 They review the conversations between the crew and air-traffic controllers. 431 00:27:22,793 --> 00:27:27,000 If you want, I can give you radar headings and take you to ANDLO at 5,000. 432 00:27:27,827 --> 00:27:29,448 Yeah. 433 00:27:30,172 --> 00:27:31,793 Yeah, that's good. 434 00:27:31,862 --> 00:27:35,137 The radar vector makes flying easier. 435 00:27:35,206 --> 00:27:38,758 The captain was happy because it was reducing his workload. 436 00:27:40,517 --> 00:27:42,310 Turn left, steer 90. 437 00:27:43,413 --> 00:27:45,172 With the controller's assistance, 438 00:27:45,241 --> 00:27:47,344 this landing should've been very simple. 439 00:27:48,034 --> 00:27:50,931 But when investigators reconstruct the plane's trajectory 440 00:27:51,000 --> 00:27:54,482 using radar information from various stations around the airport, 441 00:27:54,551 --> 00:27:56,827 they discover a shocking error. 442 00:27:58,827 --> 00:28:01,551 The 090 heading started here. 443 00:28:01,620 --> 00:28:04,344 Zero-niner-zero degrees, Delta Alpha. 444 00:28:05,517 --> 00:28:07,517 But it won't take them to ANDLO. 445 00:28:09,068 --> 00:28:12,758 The last radar vector the controller gave was incorrect. 446 00:28:14,827 --> 00:28:17,000 It sent them... - Thank you. 447 00:28:17,068 --> 00:28:19,000 ...closer to the mountain. 448 00:28:21,000 --> 00:28:23,344 They were off course... 449 00:28:23,413 --> 00:28:27,137 because of following the heading they got from the radar vectoring. 450 00:28:27,206 --> 00:28:30,827 They found themselves in this under-shoot situation. 451 00:28:31,137 --> 00:28:34,931 - You're inside there. You should've started with 070. - Yeah. 452 00:28:36,000 --> 00:28:39,379 Investigators are also troubled by the controller's choice of words 453 00:28:39,448 --> 00:28:41,724 when he warned the pilots, incorrectly, 454 00:28:41,793 --> 00:28:43,793 that they were headed to the right. 455 00:28:43,862 --> 00:28:47,310 Delta Alpha, you're passing to the right of ANDLO. 456 00:28:48,758 --> 00:28:50,655 From the pilots' perspective, 457 00:28:50,724 --> 00:28:54,206 the plane was on the left side of the runway, not the right. 458 00:28:54,275 --> 00:28:56,137 It could only add to their confusion. 459 00:28:57,551 --> 00:29:00,827 It was very poor guidance, 460 00:29:00,896 --> 00:29:03,758 because he didn't employ the usual terminology. 461 00:29:11,103 --> 00:29:14,172 Investigators recommend that controllers use only compass points 462 00:29:14,241 --> 00:29:16,517 when giving directions, 463 00:29:16,586 --> 00:29:18,758 never the words "right" and "left." 464 00:29:22,241 --> 00:29:25,862 The controller's mistakes clearly brought the plane closer to the mountain. 465 00:29:25,931 --> 00:29:28,068 Turn left, steer 90. 466 00:29:28,137 --> 00:29:31,275 Zero-niner... But once again, 467 00:29:31,344 --> 00:29:34,482 investigators feel they don't have the whole story. 468 00:29:40,586 --> 00:29:45,344 It's not something totally abnormal to start a descent from this situation. 469 00:29:45,413 --> 00:29:47,103 Flaps towards 2. 470 00:29:47,448 --> 00:29:48,896 Flaps towards 2. 471 00:29:50,482 --> 00:29:53,103 It's not what you're expected to do every day, 472 00:29:53,172 --> 00:29:57,448 but it's not outside the tolerance of... 473 00:29:57,517 --> 00:29:59,758 the concept of this approach. 474 00:29:59,827 --> 00:30:01,827 Gear down. 475 00:30:03,206 --> 00:30:07,206 When investigators study the plane's reconstructed flight path, 476 00:30:07,275 --> 00:30:11,448 they discover something more alarming than the plane's horizontal misdirection. 477 00:30:11,517 --> 00:30:13,137 As it circled the mountain, 478 00:30:13,206 --> 00:30:17,000 the plane inexplicably entered a dangerously steep and rapid descent. 479 00:30:19,655 --> 00:30:22,793 Perhaps 2.5 times, uh, the normal rate of descent. 480 00:30:24,000 --> 00:30:25,758 That's lethal at that altitude. 481 00:30:27,551 --> 00:30:29,620 Without the steep descent, 482 00:30:29,689 --> 00:30:31,275 they would've cleared the mountain. 483 00:30:31,344 --> 00:30:34,000 If the vertical, uh... 484 00:30:34,068 --> 00:30:36,000 trajectory had been correct, 485 00:30:36,068 --> 00:30:38,413 they would have no problem at all. 486 00:30:38,482 --> 00:30:41,137 Finding the cause of that sudden descent 487 00:30:41,206 --> 00:30:44,448 is now key to understanding why 87 people died 488 00:30:44,517 --> 00:30:47,103 in one of the most advanced passenger planes on Earth. 489 00:30:52,655 --> 00:30:55,000 Authorized for final approach, 05. 490 00:30:58,793 --> 00:31:03,241 The descent was initiated at 18:19:38. 491 00:31:03,310 --> 00:31:04,620 That... 492 00:31:04,689 --> 00:31:06,379 Delta Alpha. 493 00:31:07,310 --> 00:31:09,000 ...is the point of no return. 494 00:31:09,896 --> 00:31:12,482 By studying Flight 148's trajectory, 495 00:31:12,551 --> 00:31:17,379 investigators determine that the rapid descent began 60 seconds before the crash. 496 00:31:21,896 --> 00:31:24,827 There is no indication on tape that the descent was deliberate. 497 00:31:24,896 --> 00:31:28,689 How it happened and why the crew didn't notice is a mystery. 498 00:31:34,000 --> 00:31:37,310 It should be a no-brainer, keeping track of the altitude. 499 00:31:37,965 --> 00:31:39,827 The cockpit altimeter gives pilots 500 00:31:39,896 --> 00:31:41,827 a constant readout of their altitude. 501 00:31:42,586 --> 00:31:44,793 The altimeter is a very precise instrument; 502 00:31:44,862 --> 00:31:48,482 they've become very reliable, they're accurate to within five or 10 feet. 503 00:31:48,551 --> 00:31:52,275 Ignoring it would be a major error in flying protocol. 504 00:31:55,068 --> 00:31:56,689 Flaps towards 2. 505 00:31:56,758 --> 00:31:59,793 The recording reveals just one single remark from the crew 506 00:31:59,862 --> 00:32:01,448 about their descent. 507 00:32:03,241 --> 00:32:04,793 We have to watch our descent. 508 00:32:05,793 --> 00:32:08,586 It occurred 16 seconds before the crash. 509 00:32:08,655 --> 00:32:11,551 The captain had just extended the speed brakes. 510 00:32:11,620 --> 00:32:14,448 The aircraft was accelerating abnormally. 511 00:32:15,172 --> 00:32:18,931 The captain started to realize there was something wrong with the descent rate. 512 00:32:19,758 --> 00:32:22,068 But the first officer changed the subject. 513 00:32:23,551 --> 00:32:26,413 The approach axis. We're hitting the axis a half-point off. 514 00:32:26,482 --> 00:32:28,586 There. 515 00:32:28,655 --> 00:32:30,413 It was 60. Check it out. 516 00:32:33,413 --> 00:32:35,344 He refocused... 517 00:32:35,413 --> 00:32:39,344 the captain's attention on the lateral situation... 518 00:32:39,965 --> 00:32:42,206 ...rather than the vertical situation, 519 00:32:42,275 --> 00:32:44,137 which was the main problem, of course. 520 00:32:44,206 --> 00:32:47,655 And they both failed to recognize the situation. 521 00:32:47,724 --> 00:32:49,827 I think they were planning... 522 00:32:49,896 --> 00:32:53,344 they were gonna break out of the clouds so they'd be able to see the runway, 523 00:32:53,413 --> 00:32:56,034 and they wouldn't need to do the full instrument approach. 524 00:32:56,103 --> 00:32:58,068 It was 60. Check it... 525 00:32:58,137 --> 00:33:00,827 But the plane never left the clouds. 526 00:33:01,827 --> 00:33:03,275 There's an old adage in aviation: 527 00:33:03,344 --> 00:33:06,206 Rocks have been known to hide out in those clouds. 528 00:33:06,275 --> 00:33:07,655 Merde! 529 00:33:08,689 --> 00:33:13,206 It now seems clear that the crew was not monitoring their altitude closely enough. 530 00:33:13,655 --> 00:33:15,931 But a bigger mystery remains. 531 00:33:16,620 --> 00:33:19,896 We can only guess why... What caused that deadly descent? 532 00:33:26,137 --> 00:33:29,551 After months of work, investigators may finally have the answer. 533 00:33:29,620 --> 00:33:33,310 All the available flight data from the damaged Quick Access Recorder 534 00:33:33,379 --> 00:33:35,241 has been recovered. 535 00:33:35,310 --> 00:33:39,137 We were very anxious to be able to read as much as we could. 536 00:33:41,344 --> 00:33:44,655 The data confirms that just before the crash, 537 00:33:44,724 --> 00:33:48,482 the plane was speeding toward the ground at an extremely high rate: 538 00:33:48,551 --> 00:33:50,965 3,300 feet per minute. 539 00:33:51,827 --> 00:33:55,344 It also confirms that the angle of descent was dangerously steep. 540 00:33:57,448 --> 00:34:00,379 Much greater than the 3.3 degrees selected by the captain. 541 00:34:00,448 --> 00:34:02,862 3.3... degrees. 542 00:34:05,103 --> 00:34:07,482 That's quite a difference. 543 00:34:07,551 --> 00:34:11,827 Investigators now wonder: Did the autopilot malfunction? 544 00:34:11,896 --> 00:34:15,931 Did it somehow fail to obey the captain's safe descent angle 545 00:34:16,000 --> 00:34:18,413 and send the plane into a deadly nosedive? 546 00:34:19,206 --> 00:34:22,034 But what state was it in before the accident? 547 00:34:23,965 --> 00:34:27,413 Unfortunately, the flight-control unit which houses the autopilot 548 00:34:27,482 --> 00:34:30,827 is too badly damaged to provide any definitive answers. 549 00:34:33,448 --> 00:34:37,448 We could never demonstrate that this FCU on this aircraft, 550 00:34:37,517 --> 00:34:40,482 during this flight, uh... 551 00:34:40,551 --> 00:34:42,310 functioned properly or not. 552 00:34:43,310 --> 00:34:47,241 But then, when he returns to studying the flight data, 553 00:34:47,310 --> 00:34:51,482 Paries discovers something that may finally reveal the cause of the crash. 554 00:34:51,551 --> 00:34:55,000 He notices a similarity between two key numbers: 555 00:34:55,068 --> 00:34:58,379 The plane's vertical speed, 3,300 feet per minute; 556 00:34:58,448 --> 00:35:01,655 and the intended flight-path angle, 3.3 degrees. 557 00:35:05,758 --> 00:35:07,275 Coincidence? 558 00:35:09,620 --> 00:35:13,172 Paries uses a flight simulator to test a new theory. 559 00:35:13,241 --> 00:35:16,586 Can you show me a descent of 3,300 feet per minute? 560 00:35:16,655 --> 00:35:20,068 He believes that the similarity is no mere coincidence. 561 00:35:22,000 --> 00:35:26,172 On the autopilot, there are two descent modes: 562 00:35:26,241 --> 00:35:29,586 Flight-path angle and vertical speed. 563 00:35:30,034 --> 00:35:32,827 But they are both displayed on the same window. 564 00:35:34,344 --> 00:35:37,655 So 3,300 is abbreviated to 33. 565 00:35:38,655 --> 00:35:43,310 Now, show me a flight angle of -3.3 degrees. 566 00:35:44,275 --> 00:35:47,034 And the problem on this aircraft... 567 00:35:47,344 --> 00:35:51,689 ...was the two values were visible on the same window 568 00:35:51,758 --> 00:35:54,172 and controlled by the same knob. 569 00:35:54,241 --> 00:35:57,000 3.3... degrees. 570 00:35:59,517 --> 00:36:01,275 - 3.3 degrees. 571 00:36:01,344 --> 00:36:03,137 Paries strongly suspects 572 00:36:03,206 --> 00:36:06,034 that the confusing display tripped up Captain Hecquet. 573 00:36:07,931 --> 00:36:11,448 So... it wouldn't be hard to make that mistake, would it? 574 00:36:11,517 --> 00:36:15,172 The confusion is quite easy between the two modes, 575 00:36:15,241 --> 00:36:18,000 if you don't do it carefully. 576 00:36:20,034 --> 00:36:23,551 If the captain failed to push the mode-selector knob, 577 00:36:23,620 --> 00:36:25,965 then entering 33 would not have initiated 578 00:36:26,034 --> 00:36:29,000 a safe 3.3-degree angle of descent. 579 00:36:31,103 --> 00:36:34,172 Instead, it would've put the plane into a deadly rate of descent 580 00:36:34,241 --> 00:36:36,551 of 3,300 feet per minute. 581 00:36:42,310 --> 00:36:44,206 Two months after the crash, 582 00:36:44,275 --> 00:36:49,103 another Air Inter plane enters a dangerously steep descent for the same reason. 583 00:36:50,586 --> 00:36:55,103 The crew only discovered the problem when they... broke out of the clouds. 584 00:36:57,172 --> 00:37:00,896 Those pilots also confused the plane's flight-path angle 585 00:37:00,965 --> 00:37:03,068 with its vertical speed. 586 00:37:03,137 --> 00:37:06,620 They were lucky enough to have a much higher cloud base 587 00:37:06,689 --> 00:37:08,689 so they could correct the problem. 588 00:37:09,758 --> 00:37:13,931 Further research reveals an industry-wide problem with the A320. 589 00:37:15,620 --> 00:37:18,551 Many people confused these modes, especially during training. 590 00:37:18,620 --> 00:37:22,034 And many of them fell in the trap even after the training. 591 00:37:25,034 --> 00:37:26,896 Eager to test his new theory, 592 00:37:26,965 --> 00:37:32,000 Jean Paries programs a simulator with all the known data from Flight 148. 593 00:37:33,620 --> 00:37:36,034 He then inputs the same rate of descent 594 00:37:36,103 --> 00:37:38,965 he believes the Air Inter pilots selected. 595 00:37:42,310 --> 00:37:44,103 If Paries is correct, 596 00:37:44,172 --> 00:37:47,137 the simulation will end with the plane hitting the mountain. 597 00:37:49,068 --> 00:37:50,551 But it doesn't. 598 00:37:50,620 --> 00:37:52,137 We're missing something. 599 00:37:52,655 --> 00:37:54,379 Strangely, this didn't lead to a crash. 600 00:37:54,965 --> 00:37:58,482 Every approach would overfly this obstacle 601 00:37:58,551 --> 00:38:01,275 by a significant margin. 602 00:38:01,344 --> 00:38:03,413 Have we factored in the wind? 603 00:38:04,310 --> 00:38:08,448 We started to work on other, alternate hypotheses. 604 00:38:08,517 --> 00:38:12,793 Let's try again... but initiate the turn sooner. 605 00:38:13,724 --> 00:38:16,413 But nothing was really, uh, credible. 606 00:38:16,482 --> 00:38:18,896 No matter how hard he tries, 607 00:38:18,965 --> 00:38:21,206 Paries cannot simulate the crash. 608 00:38:23,172 --> 00:38:26,758 Unable to explain why, he turns to the plane's manufacturer for help. 609 00:38:27,965 --> 00:38:30,965 Thanks for bringing this to my attention. After much research, 610 00:38:31,034 --> 00:38:34,172 an Airbus designer comes to Paries with an explanation 611 00:38:34,241 --> 00:38:37,172 about a little-known element of the autopilot's design. 612 00:38:38,517 --> 00:38:43,103 In emergency situations where the A320 needs to change direction quickly, 613 00:38:43,172 --> 00:38:48,827 the autopilot is programmed to reverse the plane's direction at twice the normal rate. 614 00:38:49,655 --> 00:38:53,068 The reaction of the autopilot would be much faster. 615 00:38:53,724 --> 00:38:58,206 And these cases were typically when you were descending and, uh, 616 00:38:58,275 --> 00:39:00,206 asking the autopilot to climb, 617 00:39:00,275 --> 00:39:03,172 or climbing and asking the autopilot to descend. 618 00:39:04,034 --> 00:39:06,758 We immediately went back to the data 619 00:39:06,827 --> 00:39:09,862 at the very second to which... 620 00:39:09,931 --> 00:39:12,689 the descent was commanded by the crew. 621 00:39:12,758 --> 00:39:14,724 Gear down. 622 00:39:14,793 --> 00:39:17,344 Paries discovers a tragic coincidence. 623 00:39:20,379 --> 00:39:23,206 Sadly, we found at this very second, 624 00:39:23,275 --> 00:39:24,965 there was turbulence. 625 00:39:25,034 --> 00:39:26,827 There was an ascent. 626 00:39:26,896 --> 00:39:28,931 It was very slight, but there it is. 627 00:39:29,000 --> 00:39:31,034 The momentary turbulence 628 00:39:31,103 --> 00:39:33,000 caused the plane to climb slightly. 629 00:39:34,896 --> 00:39:37,137 And this led to a positive... 630 00:39:37,206 --> 00:39:40,034 600-feet-per-minute vertical speed 631 00:39:40,103 --> 00:39:42,034 for maybe half a second. 632 00:39:42,103 --> 00:39:44,620 It was during that same half-second 633 00:39:44,689 --> 00:39:46,965 that the crew commanded the plane to descend. 634 00:39:47,758 --> 00:39:52,482 The autopilot read this as an emergency requiring a blazingly fast descent. 635 00:39:53,448 --> 00:39:55,586 That could be it. 636 00:39:56,413 --> 00:39:59,689 Investigators now contemplate a terrible thought: 637 00:39:59,758 --> 00:40:04,482 Could a random gust of wind, hitting at exactly the wrong split second, 638 00:40:04,551 --> 00:40:06,827 have been the difference between life and death? 639 00:40:07,931 --> 00:40:09,448 Here it comes... 640 00:40:14,448 --> 00:40:16,448 And we got a crash. 641 00:40:16,517 --> 00:40:19,793 Paries's theory explains every aspect of the crash. 642 00:40:20,620 --> 00:40:23,689 The crew's confusion with the autopilot display... 643 00:40:23,758 --> 00:40:26,793 3.3... degrees. 644 00:40:28,103 --> 00:40:30,931 ...caused the plane to descend dangerously close to the mountain. 645 00:40:33,413 --> 00:40:37,103 Turbulence and an obscure safety feature brought it even closer. 646 00:40:37,931 --> 00:40:39,689 It was a fatal combination. 647 00:40:41,689 --> 00:40:44,517 It's a fascinating lesson... 648 00:40:44,586 --> 00:40:48,241 about the, uh, random dimension of accidents. 649 00:40:48,310 --> 00:40:51,620 Half a second before, half a second later, 650 00:40:51,689 --> 00:40:53,931 they wouldn't have the accident. 651 00:40:55,137 --> 00:40:58,000 The discovery of a confusing cockpit display... 652 00:40:59,586 --> 00:41:02,482 ...has enormous implications for the entire industry. 653 00:41:03,620 --> 00:41:08,344 The flight instrumentation of aircraft like the DC-10, 654 00:41:08,413 --> 00:41:11,620 MD11s, the 74s and so on, 655 00:41:11,689 --> 00:41:14,689 all the Boeing products and all the commuter products 656 00:41:14,758 --> 00:41:17,586 that were using that avionics suite 657 00:41:17,655 --> 00:41:20,206 had this vulnerability about it. 658 00:41:21,862 --> 00:41:24,275 Investigators now face a daunting question 659 00:41:24,344 --> 00:41:26,758 affecting aircraft safety around the world. 660 00:41:28,413 --> 00:41:32,000 If the design of the autopilot interface isn't changed, 661 00:41:32,068 --> 00:41:34,137 how many more people could die? 662 00:41:41,275 --> 00:41:47,137 There's mounting evidence that the design of the autopilot interface on Airbus A320s 663 00:41:47,206 --> 00:41:51,344 led the Air Inter pilots to accidentally dial in a dangerous rate of descent. 664 00:41:51,413 --> 00:41:54,275 3.3... degrees. 665 00:41:55,034 --> 00:41:58,172 We felt a need to start the industry to work on this. 666 00:41:59,448 --> 00:42:02,827 The plane's manufacturer, Airbus, responds immediately. 667 00:42:03,724 --> 00:42:06,827 The main change, which was very quickly made, 668 00:42:06,896 --> 00:42:10,000 was to change the display window. 669 00:42:11,068 --> 00:42:12,620 With the new design, 670 00:42:12,689 --> 00:42:16,413 if a pilot selects a vertical speed of 3,300, 671 00:42:16,482 --> 00:42:19,206 the entire four-digit number is displayed. 672 00:42:20,206 --> 00:42:23,068 So... the confusion between an angle 673 00:42:23,137 --> 00:42:25,724 and the vertical speed was no longer possible. 674 00:42:26,620 --> 00:42:29,896 For investigators, only one mystery remains. 675 00:42:33,448 --> 00:42:37,689 All Airbus A320 jets are designed to be equipped with a safety device 676 00:42:37,758 --> 00:42:41,137 known as a Ground Proximity Warning System, 677 00:42:41,206 --> 00:42:43,344 or GPWS. 678 00:42:43,413 --> 00:42:46,862 Which is a downward-looking single-purpose radar 679 00:42:46,931 --> 00:42:50,931 that tells you how high you are above the ground directly beneath the airplane. 680 00:42:51,000 --> 00:42:53,931 And if it gets to be too low, it'll set off a warning. 681 00:42:54,000 --> 00:42:55,655 Pull Up. 682 00:42:55,724 --> 00:42:57,827 Terrain. Pull up. 683 00:42:57,896 --> 00:43:01,241 But Captain Hecquet... - We have to watch our descent. 684 00:43:01,310 --> 00:43:04,724 ...never received a warning for one very simple reason: 685 00:43:04,793 --> 00:43:07,758 His A320 didn't have that alarm. 686 00:43:09,379 --> 00:43:10,931 Merde! 687 00:43:24,482 --> 00:43:27,241 The first question, of course, was why... 688 00:43:27,310 --> 00:43:29,103 the aircraft was not equipped. 689 00:43:31,172 --> 00:43:33,586 So it's not part of the Minimum Equipment List? 690 00:43:35,758 --> 00:43:38,586 The Air Inter management had decided... 691 00:43:38,655 --> 00:43:41,793 they did not like the false warnings 692 00:43:41,862 --> 00:43:43,620 that had been produced 693 00:43:43,689 --> 00:43:46,103 by GPWS equipment. 694 00:43:48,379 --> 00:43:52,275 Normally, most planes fly slower than 250 knots 695 00:43:52,344 --> 00:43:53,896 when under 10,000 feet. 696 00:43:53,965 --> 00:43:57,689 But we flew at 350 knots until the final approach. 697 00:44:02,517 --> 00:44:06,241 So at those speeds, GPWS was always giving off false alarms. 698 00:44:13,034 --> 00:44:15,448 This decision, while legal, 699 00:44:15,517 --> 00:44:18,965 prevented the pilots from having one last line of defence 700 00:44:19,034 --> 00:44:21,000 before crashing into the mountain. 701 00:44:21,068 --> 00:44:25,620 It's impossible to imagine that the pilot wouldn't have pulled up 702 00:44:25,689 --> 00:44:27,379 if he'd heard the alarm. 703 00:44:29,793 --> 00:44:33,206 We should have a GPWS on commercial flights. 704 00:44:33,275 --> 00:44:35,724 In any case, yes, that's... 705 00:44:35,793 --> 00:44:38,586 a... an obvious conclusion. 706 00:44:38,655 --> 00:44:42,275 The report will list these causes: Flight Deck Ergonomics... 707 00:44:42,344 --> 00:44:45,586 Investigators conclude that there was no single cause 708 00:44:45,655 --> 00:44:47,517 for the crash of Flight 148. 709 00:44:49,379 --> 00:44:51,965 The tragedy involved in an ill-fated combination 710 00:44:52,034 --> 00:44:54,965 of many different weaknesses in the airline industry. 711 00:44:58,379 --> 00:45:02,137 We made... 35 or so recommendations, 712 00:45:02,206 --> 00:45:05,034 including pilot training... 713 00:45:05,103 --> 00:45:09,206 about the Ground Proximity Warning System and so on. 714 00:45:10,482 --> 00:45:13,206 The recommendations lead to sweeping changes. 715 00:45:14,793 --> 00:45:17,448 Pilots must now have more A320 training 716 00:45:17,517 --> 00:45:19,586 before getting behind the controls. 717 00:45:22,206 --> 00:45:25,620 One of the two pilots now need to have 718 00:45:25,689 --> 00:45:28,103 at least 300 hours on the plane. 719 00:45:28,172 --> 00:45:30,655 They estimated that 300 hours were enough. 720 00:45:32,931 --> 00:45:34,827 Another change: 721 00:45:34,896 --> 00:45:37,655 The design of a more heat-resistant black box. 722 00:45:38,551 --> 00:45:40,413 The FAA did a test, 723 00:45:40,482 --> 00:45:44,689 did some studies with the thermal characteristics of post-crash fires, 724 00:45:44,758 --> 00:45:47,655 where it came up with a value of, uh, 725 00:45:47,724 --> 00:45:51,758 260 degrees C for 10 hours. 726 00:45:52,724 --> 00:45:54,206 Delta Alpha, your position? 727 00:45:56,586 --> 00:45:58,413 Air Inter Delta Alpha, Strasbourg. 728 00:46:02,482 --> 00:46:05,448 As a result of the Strasbourg crash, 729 00:46:05,517 --> 00:46:07,689 the A320 is now a safer plane. 730 00:46:09,482 --> 00:46:12,034 You can only get this... 731 00:46:12,103 --> 00:46:16,758 change if there is what people perceive to be a good reason. 732 00:46:18,241 --> 00:46:19,724 And sadly, 733 00:46:19,793 --> 00:46:22,689 a good reason is still an accident. 734 00:46:23,103 --> 00:46:26,103 But improved aviation technology is still no substitute 735 00:46:26,172 --> 00:46:29,448 for well-trained, well-prepared pilots. 736 00:46:32,793 --> 00:46:35,862 There's an old axiom in aviation, that you're taught early on: 737 00:46:35,931 --> 00:46:38,965 Never let an airplane take you somewhere 738 00:46:39,034 --> 00:46:42,724 that your brain hasn't visited at least five minutes ahead of time. 739 00:46:42,793 --> 00:46:45,103 This is an excellent example of a flight crew 740 00:46:45,172 --> 00:46:47,655 that didn't follow that particular axiom. 741 00:46:59,724 --> 00:47:01,827 difuze