1 00:00:07,966 --> 00:00:10,260 At the heart of every modern aircraft 2 00:00:10,344 --> 00:00:13,263 is a computer that's vital for safe flight. 3 00:00:10,344 --> 00:00:13,263 is a computer that's vital for safe flight. 4 00:00:13,305 --> 00:00:14,765 Simply put, it'd 5 00:00:14,848 --> 00:00:19,061 be nearly impossible to fly this airplane safely 6 00:00:14,848 --> 00:00:19,061 be nearly impossible to fly this airplane safely 7 00:00:19,102 --> 00:00:21,813 without flight computers. 8 00:00:21,897 --> 00:00:24,775 But those computers rely on a steady stream 9 00:00:21,897 --> 00:00:24,775 But those computers rely on a steady stream 10 00:00:24,858 --> 00:00:26,193 of accurate data. 11 00:00:26,276 --> 00:00:28,278 Starting to pass through the layers. 12 00:00:28,362 --> 00:00:29,780 When they don't get it... 13 00:00:29,821 --> 00:00:31,949 Can't keep this damn thing level. 14 00:00:29,821 --> 00:00:31,949 Can't keep this damn thing level. 15 00:00:32,032 --> 00:00:33,492 Oh, ah. 16 00:00:33,575 --> 00:00:37,079 The results are sometimes catastrophic. 17 00:00:33,575 --> 00:00:37,079 The results are sometimes catastrophic. 18 00:00:37,120 --> 00:00:38,789 What are they doing so low? 19 00:00:38,872 --> 00:00:40,832 My airspeed indicator is not working. 20 00:00:40,916 --> 00:00:43,794 Something's wrong here. 21 00:00:40,916 --> 00:00:43,794 Something's wrong here. 22 00:00:43,877 --> 00:00:45,295 God, god. 23 00:00:46,588 --> 00:00:47,297 What was that? 24 00:00:47,381 --> 00:00:48,298 We got to get out. 25 00:00:47,381 --> 00:00:48,298 We got to get out. 26 00:00:51,134 --> 00:00:54,304 If they can't figure out what went wrong, 27 00:00:51,134 --> 00:00:54,304 If they can't figure out what went wrong, 28 00:00:54,388 --> 00:00:58,892 this could be the end of the B-2 bomber program. 29 00:00:58,976 --> 00:01:02,145 How can computers designed to aid pilots 30 00:00:58,976 --> 00:01:02,145 How can computers designed to aid pilots 31 00:01:02,187 --> 00:01:04,356 hinder them instead? 32 00:01:04,439 --> 00:01:07,693 Investigators search for the cause of three accidents 33 00:01:04,439 --> 00:01:07,693 Investigators search for the cause of three accidents 34 00:01:07,776 --> 00:01:10,362 triggered by bad data. 35 00:01:10,445 --> 00:01:12,322 You don't just fly with a stick and a rudder 36 00:01:10,445 --> 00:01:12,322 You don't just fly with a stick and a rudder 37 00:01:12,406 --> 00:01:14,825 and look out the window anymore. 38 00:01:14,866 --> 00:01:16,159 Ladies and gentlemen, 39 00:01:16,243 --> 00:01:17,536 we are starting our approach. 40 00:01:17,619 --> 00:01:19,538 We lost both engines. 41 00:01:17,619 --> 00:01:19,538 We lost both engines. 42 00:01:19,621 --> 00:01:20,998 Mask over your nose. Emergency descent. 43 00:01:21,081 --> 00:01:21,999 Mayday, Mayday! 44 00:01:22,082 --> 00:01:23,375 Brace for impact! 45 00:01:28,297 --> 00:01:29,339 It's gonna crash! 46 00:01:44,813 --> 00:01:45,522 You're good to go, sir. 47 00:01:45,606 --> 00:01:47,482 Thank you. 48 00:01:47,524 --> 00:01:50,193 Major Ryan Link and Captain Justin Grieve 49 00:01:47,524 --> 00:01:50,193 Major Ryan Link and Captain Justin Grieve 50 00:01:50,277 --> 00:01:53,196 are ending a four-month deployment at Andersen Air Force 51 00:01:53,280 --> 00:01:56,033 base in Guam. 52 00:01:53,280 --> 00:01:56,033 base in Guam. 53 00:01:56,074 --> 00:01:57,534 OK, let's head home then. 54 00:01:57,618 --> 00:01:59,369 Copy that. 55 00:01:59,453 --> 00:02:01,705 They were beginning a 16-hour continuous 56 00:01:59,453 --> 00:02:01,705 They were beginning a 16-hour continuous 57 00:02:01,788 --> 00:02:04,082 flight back to Whiteman Air Force base, 58 00:02:04,166 --> 00:02:06,668 which was our home base. 59 00:02:04,166 --> 00:02:06,668 which was our home base. 60 00:02:06,710 --> 00:02:09,713 They're returning home in a unique warplane, 61 00:02:09,796 --> 00:02:14,885 a B-2 bomber called the Spirit of Kansas. 62 00:02:09,796 --> 00:02:14,885 a B-2 bomber called the Spirit of Kansas. 63 00:02:14,926 --> 00:02:16,637 Tower of Death 5, start up is complete. 64 00:02:16,720 --> 00:02:18,221 You can activate our flight plan. 65 00:02:16,720 --> 00:02:18,221 You can activate our flight plan. 66 00:02:18,263 --> 00:02:20,057 It's a 7,000-mile journey 67 00:02:20,140 --> 00:02:25,562 home from Guam to Whiteman Air Force base in Missouri. 68 00:02:20,140 --> 00:02:25,562 home from Guam to Whiteman Air Force base in Missouri. 69 00:02:25,604 --> 00:02:28,940 Major Link is a qualified instructor on the B-2. 70 00:02:29,024 --> 00:02:31,443 Captain Grieve is the mission commander, 71 00:02:29,024 --> 00:02:31,443 Captain Grieve is the mission commander, 72 00:02:31,526 --> 00:02:37,240 with more than 2,500 hours of military flying experience. 73 00:02:31,526 --> 00:02:37,240 with more than 2,500 hours of military flying experience. 74 00:02:37,324 --> 00:02:39,076 First MCT. 75 00:02:44,873 --> 00:02:46,750 The very first time I flew the B-2, 76 00:02:46,792 --> 00:02:48,418 I felt like I was a bird. 77 00:02:46,792 --> 00:02:48,418 I felt like I was a bird. 78 00:02:48,502 --> 00:02:50,754 It was so smooth. 79 00:02:56,009 --> 00:02:57,886 145, rotate. 80 00:03:09,064 --> 00:03:11,775 Next thing they know, they're going straight up. 81 00:03:11,817 --> 00:03:14,194 Full power. 82 00:03:11,817 --> 00:03:14,194 Full power. 83 00:03:14,277 --> 00:03:17,614 The B-2 is only 80 feet off the ground 84 00:03:17,656 --> 00:03:19,741 and losing speed. 85 00:03:17,656 --> 00:03:19,741 and losing speed. 86 00:03:19,783 --> 00:03:23,787 The plane shakes violently. 87 00:03:23,870 --> 00:03:26,957 It's on the verge of stalling. 88 00:03:23,870 --> 00:03:26,957 It's on the verge of stalling. 89 00:03:26,998 --> 00:03:29,793 From my 15 years of flying the B-2, 90 00:03:29,876 --> 00:03:33,422 the only time I felt the B-2 shake is in the simulator. 91 00:03:29,876 --> 00:03:33,422 the only time I felt the B-2 shake is in the simulator. 92 00:03:38,468 --> 00:03:40,762 Grieve realizes they're heading for the ground. 93 00:03:43,223 --> 00:03:44,224 We got to get out. 94 00:03:57,571 --> 00:03:58,822 I'm stunned. 95 00:03:58,905 --> 00:04:01,867 The B-2 has gone through 19 years and three wars 96 00:03:58,905 --> 00:04:01,867 The B-2 has gone through 19 years and three wars 97 00:04:01,950 --> 00:04:02,826 without a crash. 98 00:04:02,909 --> 00:04:04,661 This is unheard of. 99 00:04:04,745 --> 00:04:08,498 With the B-2's price tag of $2 billion, 100 00:04:04,745 --> 00:04:08,498 With the B-2's price tag of $2 billion, 101 00:04:08,582 --> 00:04:12,836 this is the most expensive aviation accident of all time. 102 00:04:08,582 --> 00:04:12,836 this is the most expensive aviation accident of all time. 103 00:04:12,919 --> 00:04:15,839 We want to know what the heck just happened. 104 00:04:15,922 --> 00:04:20,177 Operations of the entire B-2 fleet are suspended. 105 00:04:15,922 --> 00:04:20,177 Operations of the entire B-2 fleet are suspended. 106 00:04:20,260 --> 00:04:23,221 The US Air Force appoints Brigadier General 107 00:04:23,305 --> 00:04:25,849 Floyd Carpenter to lead the investigation. 108 00:04:23,305 --> 00:04:25,849 Floyd Carpenter to lead the investigation. 109 00:04:25,891 --> 00:04:27,225 You're never going to believe this. 110 00:04:29,895 --> 00:04:33,857 Video of the takeoff shows that as the plane lifted off, 111 00:04:29,895 --> 00:04:33,857 Video of the takeoff shows that as the plane lifted off, 112 00:04:33,940 --> 00:04:36,318 it pitched nose high. 113 00:04:33,940 --> 00:04:36,318 it pitched nose high. 114 00:04:36,359 --> 00:04:38,069 Your first reaction 115 00:04:38,153 --> 00:04:42,866 when you see that airplane pitch up is like, what are they doing? 116 00:04:38,153 --> 00:04:42,866 when you see that airplane pitch up is like, what are they doing? 117 00:04:42,949 --> 00:04:45,869 Investigators study the mechanical and computer 118 00:04:45,952 --> 00:04:48,038 systems that control the jet. 119 00:04:45,952 --> 00:04:48,038 systems that control the jet. 120 00:04:48,121 --> 00:04:49,539 Perfect. 121 00:04:49,623 --> 00:04:50,499 What about the actuator? 122 00:04:57,506 --> 00:04:58,548 OK. 123 00:04:58,632 --> 00:04:59,800 They quickly determined 124 00:04:59,883 --> 00:05:01,676 that all the flight control surfaces 125 00:04:59,883 --> 00:05:01,676 that all the flight control surfaces 126 00:05:01,718 --> 00:05:05,096 were functioning on takeoff. 127 00:05:05,180 --> 00:05:06,723 The engines were not a problem. 128 00:05:05,180 --> 00:05:06,723 The engines were not a problem. 129 00:05:06,807 --> 00:05:08,099 The hydraulics weren't a problem. 130 00:05:08,183 --> 00:05:10,393 The flight controls were not a problem. 131 00:05:10,477 --> 00:05:12,395 It's a beautiful, sunny morning. 132 00:05:10,477 --> 00:05:12,395 It's a beautiful, sunny morning. 133 00:05:12,479 --> 00:05:15,232 Why does a bomber pitch its nose up and crash in a fireball 134 00:05:15,315 --> 00:05:17,567 on the runway at Guam? 135 00:05:17,651 --> 00:05:19,194 Something happened to caused 136 00:05:17,651 --> 00:05:19,194 Something happened to caused 137 00:05:19,236 --> 00:05:20,946 this airplane to pitch up. 138 00:05:21,029 --> 00:05:22,781 The heart of the B-2 bomber 139 00:05:22,864 --> 00:05:25,408 is its computerized flight control system. 140 00:05:22,864 --> 00:05:25,408 is its computerized flight control system. 141 00:05:30,997 --> 00:05:34,167 On a B-2, pilots tell the computer what they want 142 00:05:34,251 --> 00:05:39,756 the plane to do and the computer determines how to achieve that. 143 00:05:34,251 --> 00:05:39,756 the plane to do and the computer determines how to achieve that. 144 00:05:39,840 --> 00:05:42,133 Simply put, it'd be 145 00:05:39,840 --> 00:05:42,133 Simply put, it'd be 146 00:05:42,217 --> 00:05:45,554 nearly impossible to fly this airplane safely 147 00:05:45,595 --> 00:05:48,056 without flight computers. 148 00:05:45,595 --> 00:05:48,056 without flight computers. 149 00:05:48,098 --> 00:05:51,601 So did something go wrong with that system? 150 00:05:51,643 --> 00:05:54,604 The investigators turn to data from the bomber's flight 151 00:05:51,643 --> 00:05:54,604 The investigators turn to data from the bomber's flight 152 00:05:54,646 --> 00:05:58,108 recorder to discover what happened. 153 00:05:58,149 --> 00:06:00,610 The nose is lifting off the ground, 154 00:05:58,149 --> 00:06:00,610 The nose is lifting off the ground, 155 00:06:00,694 --> 00:06:05,115 but the plane registers a pitch down of minus 8 degrees. 156 00:06:05,198 --> 00:06:10,120 Now, obviously, this plane is not pitching down, 157 00:06:05,198 --> 00:06:10,120 Now, obviously, this plane is not pitching down, 158 00:06:10,203 --> 00:06:12,205 but the computer thinks it is. 159 00:06:10,203 --> 00:06:12,205 but the computer thinks it is. 160 00:06:12,289 --> 00:06:13,790 That is why I tried to lift the nose 161 00:06:13,874 --> 00:06:16,293 higher and higher and higher. 162 00:06:16,376 --> 00:06:19,296 Until it stalled. 163 00:06:16,376 --> 00:06:19,296 Until it stalled. 164 00:06:19,379 --> 00:06:26,386 So airspeed, climb angle, and altitude are all off. 165 00:06:19,379 --> 00:06:26,386 So airspeed, climb angle, and altitude are all off. 166 00:06:28,680 --> 00:06:33,143 How does that happen on this plane? 167 00:06:28,680 --> 00:06:33,143 How does that happen on this plane? 168 00:06:33,184 --> 00:06:35,478 General Carpenter wants to know 169 00:06:35,520 --> 00:06:40,150 why the flight computers were getting faulty data. 170 00:06:35,520 --> 00:06:40,150 why the flight computers were getting faulty data. 171 00:06:40,233 --> 00:06:43,361 Let's see what the pilots can tell us. 172 00:06:40,233 --> 00:06:43,361 Let's see what the pilots can tell us. 173 00:06:47,908 --> 00:06:49,826 We started up at 9:15. 174 00:06:47,908 --> 00:06:49,826 We started up at 9:15. 175 00:06:49,910 --> 00:06:52,370 A few minutes later, Major Link saw the calibration message 176 00:06:52,454 --> 00:06:54,331 during start up. 177 00:06:52,454 --> 00:06:54,331 during start up. 178 00:06:54,372 --> 00:06:55,832 Mission Commander Grieve 179 00:06:55,916 --> 00:06:58,501 tells investigators that the pilots received 180 00:06:58,543 --> 00:07:02,172 an unusual computer message. 181 00:06:58,543 --> 00:07:02,172 an unusual computer message. 182 00:07:02,255 --> 00:07:05,008 Hey, Chief, we're seeing an AIRDATA CAL message 183 00:07:05,091 --> 00:07:09,554 AIRDATA CAL stands for air data calibration. 184 00:07:05,091 --> 00:07:09,554 AIRDATA CAL stands for air data calibration. 185 00:07:09,638 --> 00:07:11,348 In the simplest terms, 186 00:07:11,431 --> 00:07:15,352 the air data calibration gives the aircraft its orientation 187 00:07:11,431 --> 00:07:15,352 the air data calibration gives the aircraft its orientation 188 00:07:15,393 --> 00:07:17,354 to the universe. 189 00:07:18,939 --> 00:07:21,191 There are 24 sensors near the nose 190 00:07:21,274 --> 00:07:25,779 of the B-2 that constantly measure air pressure. 191 00:07:21,274 --> 00:07:25,779 of the B-2 that constantly measure air pressure. 192 00:07:25,862 --> 00:07:30,033 The plane's computers use those readings to calculate altitude, 193 00:07:25,862 --> 00:07:30,033 The plane's computers use those readings to calculate altitude, 194 00:07:30,116 --> 00:07:33,203 airspeed, and angle of attack. 195 00:07:33,286 --> 00:07:35,413 If they get out of balance, it calls 196 00:07:35,497 --> 00:07:40,043 for an air data calibration, and the pilots call out maintenance. 197 00:07:35,497 --> 00:07:40,043 for an air data calibration, and the pilots call out maintenance. 198 00:07:40,085 --> 00:07:42,087 Can you put it in maintenance mode for me? 199 00:07:40,085 --> 00:07:42,087 Can you put it in maintenance mode for me? 200 00:07:46,549 --> 00:07:48,718 If any of those 24 sensors 201 00:07:46,549 --> 00:07:48,718 If any of those 24 sensors 202 00:07:48,760 --> 00:07:50,929 provides an air pressure reading that differs significantly 203 00:07:51,012 --> 00:07:53,056 from the others, 204 00:07:53,139 --> 00:07:54,724 a recalibration is needed to bring 205 00:07:53,139 --> 00:07:54,724 a recalibration is needed to bring 206 00:07:54,808 --> 00:07:57,268 them all back into agreement. 207 00:07:57,352 --> 00:07:58,520 You're good to go, sir. 208 00:08:02,148 --> 00:08:04,359 Pitot heat is on. 209 00:08:04,401 --> 00:08:07,112 Less than an hour after the recalibration... 210 00:08:04,401 --> 00:08:07,112 Less than an hour after the recalibration... 211 00:08:07,195 --> 00:08:07,946 Clear right. 212 00:08:08,029 --> 00:08:09,531 Good to line up. 213 00:08:09,572 --> 00:08:11,241 The pilots maneuver the massive bomber 214 00:08:11,282 --> 00:08:12,325 to the start of the runway. 215 00:08:11,282 --> 00:08:12,325 to the start of the runway. 216 00:08:15,662 --> 00:08:18,415 OK, go on. 217 00:08:15,662 --> 00:08:18,415 OK, go on. 218 00:08:18,498 --> 00:08:21,960 Everything was 100% routine until we hit 100 knots. 219 00:08:22,043 --> 00:08:25,880 That's when we got the FCS Master Caution. 220 00:08:22,043 --> 00:08:25,880 That's when we got the FCS Master Caution. 221 00:08:25,922 --> 00:08:28,675 Before I could even push the button, it rescinded itself. 222 00:08:32,053 --> 00:08:33,722 Stop or go? 223 00:08:33,763 --> 00:08:34,597 Go. 224 00:08:34,681 --> 00:08:37,267 Warning rescinded. 225 00:08:34,681 --> 00:08:37,267 Warning rescinded. 226 00:08:37,350 --> 00:08:39,769 In that scenario, if I was the pilot in command, 227 00:08:39,853 --> 00:08:40,687 I would continue. 228 00:08:40,770 --> 00:08:41,730 Why? 229 00:08:41,771 --> 00:08:44,149 It's not safety of flight. 230 00:08:41,771 --> 00:08:44,149 It's not safety of flight. 231 00:08:44,232 --> 00:08:48,445 When we hit 145, I called for Major Link to rotate. 232 00:08:44,232 --> 00:08:48,445 When we hit 145, I called for Major Link to rotate. 233 00:08:48,528 --> 00:08:52,657 Then it all very quickly went to hell. 234 00:09:00,040 --> 00:09:02,959 Investigators delve deeper into the calibration 235 00:09:03,043 --> 00:09:04,252 performed that day. 236 00:09:06,880 --> 00:09:07,964 You're good to go, sir. 237 00:09:08,048 --> 00:09:09,966 Thank you. 238 00:09:10,050 --> 00:09:12,802 These three weren't just off by a little. 239 00:09:10,050 --> 00:09:12,802 These three weren't just off by a little. 240 00:09:12,886 --> 00:09:15,138 They are way off. 241 00:09:15,180 --> 00:09:16,473 They discover that three 242 00:09:16,556 --> 00:09:19,642 sensors on the B-2 were providing incorrect 243 00:09:16,556 --> 00:09:19,642 sensors on the B-2 were providing incorrect 244 00:09:19,726 --> 00:09:20,477 air pressure readings... 245 00:09:20,560 --> 00:09:22,312 100 knots. 246 00:09:22,353 --> 00:09:24,064 ...and that a Master Caution 247 00:09:22,353 --> 00:09:24,064 ...and that a Master Caution 248 00:09:24,147 --> 00:09:28,068 alarm flickered on for a few seconds just before takeoff. 249 00:09:30,904 --> 00:09:32,822 At that point, we really didn't know 250 00:09:32,906 --> 00:09:35,492 how they were related, but we figured they might be. 251 00:09:35,533 --> 00:09:37,535 What was that? 252 00:09:35,533 --> 00:09:37,535 What was that? 253 00:09:37,619 --> 00:09:38,578 FCS Caution. 254 00:09:41,581 --> 00:09:43,208 The recalibrated sensors started providing 255 00:09:41,581 --> 00:09:43,208 The recalibrated sensors started providing 256 00:09:43,291 --> 00:09:45,335 faulty air data again. 257 00:09:45,376 --> 00:09:47,754 But six seconds later... 258 00:09:47,837 --> 00:09:48,713 Stop or go? 259 00:09:47,837 --> 00:09:48,713 Stop or go? 260 00:09:48,797 --> 00:09:50,465 Go. 261 00:09:50,507 --> 00:09:52,801 ...the flight computer resolved the sensor discrepancy 262 00:09:52,842 --> 00:09:56,346 and canceled the warning. 263 00:09:52,842 --> 00:09:56,346 and canceled the warning. 264 00:09:56,429 --> 00:09:58,765 What is going on with this plane's sensors? 265 00:10:01,518 --> 00:10:02,644 OK. 266 00:10:02,685 --> 00:10:06,397 So, let's start at the top. 267 00:10:02,685 --> 00:10:06,397 So, let's start at the top. 268 00:10:06,481 --> 00:10:08,817 Why the need to recalibrate in the first place? 269 00:10:15,990 --> 00:10:17,033 Huh. 270 00:10:17,117 --> 00:10:21,704 So they got delayed by a day. 271 00:10:17,117 --> 00:10:21,704 So they got delayed by a day. 272 00:10:21,788 --> 00:10:24,707 Investigators learned that while the pilots waited 273 00:10:21,788 --> 00:10:24,707 Investigators learned that while the pilots waited 274 00:10:24,791 --> 00:10:27,377 to resume their mission, the Spirit of Kansas 275 00:10:27,460 --> 00:10:28,670 sat on the tarmac. 276 00:10:31,673 --> 00:10:33,383 OK. 277 00:10:33,466 --> 00:10:38,888 So the jet was left outside for 24 hours because of the delay. 278 00:10:33,466 --> 00:10:38,888 So the jet was left outside for 24 hours because of the delay. 279 00:10:38,972 --> 00:10:41,057 So what? 280 00:10:41,141 --> 00:10:43,434 Weather records show that the night 281 00:10:41,141 --> 00:10:43,434 Weather records show that the night 282 00:10:43,518 --> 00:10:46,938 before the accident, a tropical rainstorm settled over the base. 283 00:10:50,150 --> 00:10:54,737 Tell me a rainstorm didn't take down a $2-billion airplane. 284 00:10:50,150 --> 00:10:54,737 Tell me a rainstorm didn't take down a $2-billion airplane. 285 00:10:59,993 --> 00:11:02,745 Tests confirm that the sensors exposed 286 00:10:59,993 --> 00:11:02,745 Tests confirm that the sensors exposed 287 00:11:02,829 --> 00:11:05,540 to the heaviest rainfall became saturated 288 00:11:05,582 --> 00:11:07,375 and needed recalibrating. 289 00:11:05,582 --> 00:11:07,375 and needed recalibrating. 290 00:11:11,504 --> 00:11:13,548 See, something just doesn't add up. 291 00:11:11,504 --> 00:11:13,548 See, something just doesn't add up. 292 00:11:16,092 --> 00:11:18,178 They did the recalibration. 293 00:11:16,092 --> 00:11:18,178 They did the recalibration. 294 00:11:21,848 --> 00:11:23,099 You're good to go, sir. 295 00:11:23,183 --> 00:11:24,934 Why did the recalibrated sensors 296 00:11:23,183 --> 00:11:24,934 Why did the recalibrated sensors 297 00:11:25,018 --> 00:11:27,145 then produce bad data? 298 00:11:27,228 --> 00:11:30,106 But they still ended up with faulty data. 299 00:11:27,228 --> 00:11:30,106 But they still ended up with faulty data. 300 00:11:30,190 --> 00:11:31,441 That nearly killed them. 301 00:11:39,532 --> 00:11:41,492 Full power. 302 00:11:41,576 --> 00:11:45,246 A state-of-the-art B-2 bomber stalled on takeoff 303 00:11:41,576 --> 00:11:45,246 A state-of-the-art B-2 bomber stalled on takeoff 304 00:11:45,288 --> 00:11:48,499 because of faulty data about its climb angle. 305 00:11:48,583 --> 00:11:53,046 US Air Force investigators still can't explain why that happened. 306 00:11:48,583 --> 00:11:53,046 US Air Force investigators still can't explain why that happened. 307 00:11:53,129 --> 00:11:55,798 And the pressure is on to find answers. 308 00:11:55,882 --> 00:11:59,469 If they can't figure out what went wrong, 309 00:11:55,882 --> 00:11:59,469 If they can't figure out what went wrong, 310 00:11:59,552 --> 00:12:04,641 this could be the end of the B-2 bomber program. 311 00:11:59,552 --> 00:12:04,641 this could be the end of the B-2 bomber program. 312 00:12:04,682 --> 00:12:05,975 OK. 313 00:12:06,059 --> 00:12:12,607 So, they recalibrate at 09:34. 314 00:12:06,059 --> 00:12:12,607 So, they recalibrate at 09:34. 315 00:12:14,943 --> 00:12:19,489 Nearly an hour later, the Master Caution lights up 316 00:12:14,943 --> 00:12:19,489 Nearly an hour later, the Master Caution lights up 317 00:12:19,572 --> 00:12:21,824 because of an air data issue. 318 00:12:19,572 --> 00:12:21,824 because of an air data issue. 319 00:12:21,908 --> 00:12:27,038 So what happens in those 56 minutes? 320 00:12:27,121 --> 00:12:29,999 General Carpenter reviews what the pilots 321 00:12:30,041 --> 00:12:31,876 told them about the flight. 322 00:12:31,960 --> 00:12:34,045 Routine taxi. 323 00:12:31,960 --> 00:12:34,045 Routine taxi. 324 00:12:34,128 --> 00:12:40,093 They hit the pitot heat, wait for the timer, and they're off. 325 00:12:34,128 --> 00:12:40,093 They hit the pitot heat, wait for the timer, and they're off. 326 00:12:40,176 --> 00:12:43,513 Pitot heat is a system of small heaters connected 327 00:12:43,596 --> 00:12:45,807 to each of the plane's sensors. 328 00:12:43,596 --> 00:12:45,807 to each of the plane's sensors. 329 00:12:45,848 --> 00:12:49,894 Just before takeoff, the pilots activate the heaters 330 00:12:49,978 --> 00:12:52,105 so the sensors don't freeze when the plane 331 00:12:49,978 --> 00:12:52,105 so the sensors don't freeze when the plane 332 00:12:52,188 --> 00:12:57,026 reaches colder temperatures at higher altitudes. 333 00:12:57,110 --> 00:12:59,404 Pitot heat is on. 334 00:12:57,110 --> 00:12:59,404 Pitot heat is on. 335 00:12:59,487 --> 00:13:02,949 General Carpenter asks an engineer who built the system 336 00:13:03,032 --> 00:13:05,159 if the pitot heat could have affected 337 00:13:03,032 --> 00:13:05,159 if the pitot heat could have affected 338 00:13:05,201 --> 00:13:07,036 the recalibrated sensors. 339 00:13:07,120 --> 00:13:08,246 Clear right. 340 00:13:08,329 --> 00:13:10,039 Get to line up. 341 00:13:08,329 --> 00:13:10,039 Get to line up. 342 00:13:10,123 --> 00:13:14,544 And then they turn on pitot heat when they get to the runway. 343 00:13:14,585 --> 00:13:17,714 He was really concerned when he saw 344 00:13:14,585 --> 00:13:17,714 He was really concerned when he saw 345 00:13:17,797 --> 00:13:20,383 and understood, like he only could, 346 00:13:20,425 --> 00:13:22,927 that moisture in the system and the data 347 00:13:20,425 --> 00:13:22,927 that moisture in the system and the data 348 00:13:23,011 --> 00:13:24,887 that we were putting into it to fix it 349 00:13:24,929 --> 00:13:27,223 could cause such a problem. 350 00:13:24,929 --> 00:13:27,223 could cause such a problem. 351 00:13:27,265 --> 00:13:28,808 Recalibrating the sensors 352 00:13:28,891 --> 00:13:32,103 brought the three wet ones in line with the others, 353 00:13:32,186 --> 00:13:34,856 but turning on the pitot heat evaporated 354 00:13:32,186 --> 00:13:34,856 but turning on the pitot heat evaporated 355 00:13:34,897 --> 00:13:39,819 the moisture, putting the sensors back out of alignment. 356 00:13:34,897 --> 00:13:39,819 the moisture, putting the sensors back out of alignment. 357 00:13:39,902 --> 00:13:41,446 So the data that 358 00:13:41,529 --> 00:13:44,073 was put in on the calibration now is invalid again. 359 00:13:44,157 --> 00:13:46,075 And the flight computers are now trying to resolve 360 00:13:44,157 --> 00:13:46,075 And the flight computers are now trying to resolve 361 00:13:46,159 --> 00:13:48,411 the issue with these sensors. 362 00:13:58,129 --> 00:13:59,756 What was that? 363 00:13:59,839 --> 00:14:02,592 FCS Caution. 364 00:14:02,633 --> 00:14:04,719 So then why did the faulty air 365 00:14:02,633 --> 00:14:04,719 So then why did the faulty air 366 00:14:04,761 --> 00:14:08,931 data warning disappear so quickly after it came on? 367 00:14:09,015 --> 00:14:15,063 It's seconds from takeoff so it has to make a choice. 368 00:14:09,015 --> 00:14:15,063 It's seconds from takeoff so it has to make a choice. 369 00:14:17,982 --> 00:14:19,609 The B-2's flight computer 370 00:14:19,692 --> 00:14:22,236 is constantly receiving four separate data 371 00:14:19,692 --> 00:14:22,236 is constantly receiving four separate data 372 00:14:22,278 --> 00:14:24,947 streams from all 24 sensors. 373 00:14:24,989 --> 00:14:28,368 If there's a discrepancy in the data from those streams, 374 00:14:24,989 --> 00:14:28,368 If there's a discrepancy in the data from those streams, 375 00:14:28,451 --> 00:14:31,371 the computer is programmed to select any two of the channels 376 00:14:31,454 --> 00:14:32,288 to proceed. 377 00:14:35,666 --> 00:14:37,085 It just chose wrong. 378 00:14:37,126 --> 00:14:38,795 The flight computer selected a channel that 379 00:14:38,878 --> 00:14:41,798 contained incorrect information about the pitch angle 380 00:14:38,878 --> 00:14:41,798 contained incorrect information about the pitch angle 381 00:14:41,881 --> 00:14:43,925 from the recalibrated sensors. 382 00:14:43,966 --> 00:14:44,967 145 rotate. 383 00:14:48,054 --> 00:14:50,807 12 seconds later, the bad data caused 384 00:14:50,890 --> 00:14:54,477 the B-2 to pitch up abnormally. 385 00:14:50,890 --> 00:14:54,477 the B-2 to pitch up abnormally. 386 00:14:56,145 --> 00:14:59,482 Once they rotated the aircraft on speed as they thought 387 00:14:56,145 --> 00:14:59,482 Once they rotated the aircraft on speed as they thought 388 00:14:59,524 --> 00:15:02,110 and left the ground, they were along 389 00:15:02,151 --> 00:15:03,820 for the ride at that point. 390 00:15:02,151 --> 00:15:03,820 for the ride at that point. 391 00:15:03,861 --> 00:15:05,530 Full power. 392 00:15:05,613 --> 00:15:08,408 That steep pitch up caught the Spirit of Kansas crew 393 00:15:08,491 --> 00:15:11,994 completely off guard, leaving them vulnerable to the effects 394 00:15:08,491 --> 00:15:11,994 completely off guard, leaving them vulnerable to the effects 395 00:15:12,078 --> 00:15:14,414 of the faulty data. 396 00:15:14,497 --> 00:15:17,667 There's no way a pilot or a maintainer 397 00:15:14,497 --> 00:15:17,667 There's no way a pilot or a maintainer 398 00:15:17,750 --> 00:15:19,710 would understand the system well enough 399 00:15:19,794 --> 00:15:22,505 to realize what could have happened when 400 00:15:19,794 --> 00:15:22,505 to realize what could have happened when 401 00:15:22,588 --> 00:15:24,132 they did that data calibration. 402 00:15:29,345 --> 00:15:32,056 Within two months, the B-2's flight computer 403 00:15:32,140 --> 00:15:35,184 was reprogrammed to address the fault. 404 00:15:32,140 --> 00:15:35,184 was reprogrammed to address the fault. 405 00:15:35,268 --> 00:15:39,856 There have been no issues with bad data since. 406 00:15:35,268 --> 00:15:39,856 There have been no issues with bad data since. 407 00:15:39,939 --> 00:15:42,358 Well, in the end, safety is everything. 408 00:15:42,442 --> 00:15:46,863 It doesn't matter if it's an airliner, a fighter jet, 409 00:15:42,442 --> 00:15:46,863 It doesn't matter if it's an airliner, a fighter jet, 410 00:15:46,946 --> 00:15:48,781 a space plane, or a stealth bomber. 411 00:15:51,367 --> 00:15:54,370 As sophisticated as aircraft have become, 412 00:15:54,454 --> 00:15:57,331 there are still situations where crucial information 413 00:15:54,454 --> 00:15:57,331 there are still situations where crucial information 414 00:15:57,373 --> 00:15:59,250 is communicated by radio. 415 00:15:59,333 --> 00:16:03,921 In those scenarios, a failure to check and recheck that data 416 00:15:59,333 --> 00:16:03,921 In those scenarios, a failure to check and recheck that data 417 00:16:04,005 --> 00:16:05,756 can result in disaster. 418 00:16:09,760 --> 00:16:13,014 Independent Air Flight 1851 cruises 419 00:16:13,055 --> 00:16:16,058 above the Atlantic Ocean. 420 00:16:13,055 --> 00:16:16,058 above the Atlantic Ocean. 421 00:16:16,142 --> 00:16:21,439 There are 137 passengers aboard the Boeing 707. 422 00:16:16,142 --> 00:16:21,439 There are 137 passengers aboard the Boeing 707. 423 00:16:21,522 --> 00:16:24,233 Santa Maria, Independent Air 1851, 424 00:16:24,317 --> 00:16:27,069 requesting MET report. 425 00:16:27,153 --> 00:16:29,030 Flight engineer Jorge Gonzalez 426 00:16:29,071 --> 00:16:31,991 checks the weather ahead. 427 00:16:32,074 --> 00:16:39,040 He's a US Air Force veteran, as is captain Leon James Dougherty. 428 00:16:32,074 --> 00:16:39,040 He's a US Air Force veteran, as is captain Leon James Dougherty. 429 00:16:41,000 --> 00:16:41,876 Let's request to send. 430 00:16:44,712 --> 00:16:48,257 Santa Maria control, Independent Air 1851 431 00:16:44,712 --> 00:16:48,257 Santa Maria control, Independent Air 1851 432 00:16:48,341 --> 00:16:50,343 would like to descend. 433 00:16:50,426 --> 00:16:53,095 First officer Sammy Adcock started with Independent 434 00:16:50,426 --> 00:16:53,095 First officer Sammy Adcock started with Independent 435 00:16:53,179 --> 00:16:54,388 Air two weeks ago. 436 00:16:57,058 --> 00:16:59,143 The crew was a balanced crew. 437 00:16:57,058 --> 00:16:59,143 The crew was a balanced crew. 438 00:16:59,227 --> 00:17:02,104 They had flown together for about a week or 10 days, 439 00:17:02,146 --> 00:17:04,273 and they were doing fine. 440 00:17:02,146 --> 00:17:04,273 and they were doing fine. 441 00:17:04,357 --> 00:17:06,484 The flight from Bergamo, Italy, 442 00:17:06,567 --> 00:17:10,905 will refuel at Santa Maria, an island in the remote Azores, 443 00:17:06,567 --> 00:17:10,905 will refuel at Santa Maria, an island in the remote Azores, 444 00:17:10,947 --> 00:17:15,159 before continuing to Punta Cana in the Dominican Republic. 445 00:17:10,947 --> 00:17:15,159 before continuing to Punta Cana in the Dominican Republic. 446 00:17:15,243 --> 00:17:18,329 The airport at Santa Maria is not a busy one. 447 00:17:18,412 --> 00:17:19,997 It has no radar. 448 00:17:20,081 --> 00:17:21,332 There were only three scheduled 449 00:17:20,081 --> 00:17:21,332 There were only three scheduled 450 00:17:21,415 --> 00:17:22,959 airline flights per day. 451 00:17:23,042 --> 00:17:26,837 Doesn't justify the cost of air traffic control radar. 452 00:17:30,132 --> 00:17:35,304 You're cleared 3,000 feet on QNH 1027. 453 00:17:30,132 --> 00:17:35,304 You're cleared 3,000 feet on QNH 1027. 454 00:17:35,346 --> 00:17:38,015 Runway will be one niner. 455 00:17:38,099 --> 00:17:40,560 Expect approach. 456 00:17:38,099 --> 00:17:40,560 Expect approach. 457 00:17:40,643 --> 00:17:45,815 Runway one niner, report reaching 3,000. 458 00:17:40,643 --> 00:17:45,815 Runway one niner, report reaching 3,000. 459 00:17:45,898 --> 00:17:49,151 The controller is relying solely on position 460 00:17:49,235 --> 00:17:50,861 reports from the pilot. 461 00:17:50,945 --> 00:17:54,824 So they have to be meticulous about documenting the altitude 462 00:17:50,945 --> 00:17:54,824 So they have to be meticulous about documenting the altitude 463 00:17:54,907 --> 00:17:56,075 that the aircraft is at. 464 00:17:59,662 --> 00:18:03,499 The crew needs to fly over the 2,000 foot Pico Alto 465 00:17:59,662 --> 00:18:03,499 The crew needs to fly over the 2,000 foot Pico Alto 466 00:18:03,583 --> 00:18:06,669 Mountain to reach the airport. 467 00:18:06,752 --> 00:18:08,838 On that day, the weather in Santa Maria 468 00:18:08,921 --> 00:18:10,590 was fine. 469 00:18:08,921 --> 00:18:10,590 was fine. 470 00:18:10,673 --> 00:18:16,512 There was just some cloud cover in the vicinity of Pico Alto. 471 00:18:10,673 --> 00:18:16,512 There was just some cloud cover in the vicinity of Pico Alto. 472 00:18:16,596 --> 00:18:18,347 13 minutes from the airport, 473 00:18:18,431 --> 00:18:22,018 the pilots ready the plane for landing. 474 00:18:18,431 --> 00:18:22,018 the pilots ready the plane for landing. 475 00:18:22,101 --> 00:18:24,979 OK, I'm going to go ahead and put the ILS in on my side. 476 00:18:25,021 --> 00:18:27,023 OK. 477 00:18:27,106 --> 00:18:29,525 ILS, or instrument landing system, 478 00:18:27,106 --> 00:18:29,525 ILS, or instrument landing system, 479 00:18:29,567 --> 00:18:31,527 is a navigation system that provides 480 00:18:31,611 --> 00:18:35,197 vertical and horizontal guidance to the runway. 481 00:18:31,611 --> 00:18:35,197 vertical and horizontal guidance to the runway. 482 00:18:35,281 --> 00:18:38,826 That means that he can fly in clouds until he 483 00:18:38,868 --> 00:18:40,703 gets onto final approach. 484 00:18:38,868 --> 00:18:40,703 gets onto final approach. 485 00:18:43,998 --> 00:18:46,208 As they close in on the island, 486 00:18:43,998 --> 00:18:46,208 As they close in on the island, 487 00:18:46,292 --> 00:18:48,586 an alert in the cockpit tells the pilots 488 00:18:48,669 --> 00:18:52,506 that they are 500 feet above their selected altitude. 489 00:18:48,669 --> 00:18:52,506 that they are 500 feet above their selected altitude. 490 00:18:52,548 --> 00:18:54,467 I don't know if we're going to get visual or not here. 491 00:18:57,386 --> 00:19:00,097 Starting to pass through the layers. 492 00:19:00,181 --> 00:19:04,226 But as they enter the cloud bank over the island, 493 00:19:00,181 --> 00:19:04,226 But as they enter the cloud bank over the island, 494 00:19:04,310 --> 00:19:06,062 disaster strikes. 495 00:19:06,103 --> 00:19:09,690 Can't keep this damn thing level. 496 00:19:06,103 --> 00:19:09,690 Can't keep this damn thing level. 497 00:19:09,732 --> 00:19:11,233 Pull up. 498 00:19:12,485 --> 00:19:15,237 Pull up. 499 00:19:12,485 --> 00:19:15,237 Pull up. 500 00:19:15,321 --> 00:19:16,113 Pull up. 501 00:19:22,745 --> 00:19:25,748 Four and and a half miles from Santa Maria Airport, 502 00:19:25,831 --> 00:19:27,958 Portuguese firefighters and civilians 503 00:19:25,831 --> 00:19:27,958 Portuguese firefighters and civilians 504 00:19:28,042 --> 00:19:32,505 discover what remains of Independent Air Flight 1851. 505 00:19:32,588 --> 00:19:36,217 The jet hit peak while to very near the top of the mountain. 506 00:19:32,588 --> 00:19:36,217 The jet hit peak while to very near the top of the mountain. 507 00:19:39,011 --> 00:19:41,764 The accident site was a chaotic scene. 508 00:19:39,011 --> 00:19:41,764 The accident site was a chaotic scene. 509 00:19:41,847 --> 00:19:45,893 The wreckage was strewn all over the mountain. 510 00:19:41,847 --> 00:19:45,893 The wreckage was strewn all over the mountain. 511 00:19:45,935 --> 00:19:50,231 All 144 passengers and crew on board are dead. 512 00:19:56,445 --> 00:19:59,740 By daybreak, the Portuguese Civil Aviation Authority 513 00:19:56,445 --> 00:19:59,740 By daybreak, the Portuguese Civil Aviation Authority 514 00:19:59,782 --> 00:20:01,450 arrives at the crash site. 515 00:20:01,492 --> 00:20:03,452 They are soon joined in the Azores 516 00:20:03,494 --> 00:20:05,579 by investigators from the US National 517 00:20:03,494 --> 00:20:05,579 by investigators from the US National 518 00:20:05,621 --> 00:20:07,123 Transportation Safety Board. 519 00:20:10,668 --> 00:20:13,796 So this is the flight path. 520 00:20:13,879 --> 00:20:17,675 The plane impacts the east side of Pico Alto. 521 00:20:13,879 --> 00:20:17,675 The plane impacts the east side of Pico Alto. 522 00:20:17,758 --> 00:20:19,301 Correct. 523 00:20:19,385 --> 00:20:23,139 Together, they examine the wreckage pattern. 524 00:20:19,385 --> 00:20:23,139 Together, they examine the wreckage pattern. 525 00:20:23,222 --> 00:20:29,019 All concentrated right here, 526 00:20:23,222 --> 00:20:29,019 All concentrated right here, 527 00:20:29,103 --> 00:20:33,190 sending debris over the mountain ridge. 528 00:20:33,274 --> 00:20:37,319 Scars on the ridge offer the first clues. 529 00:20:33,274 --> 00:20:37,319 Scars on the ridge offer the first clues. 530 00:20:37,361 --> 00:20:40,489 Looks like low angle, high velocity. 531 00:20:37,361 --> 00:20:40,489 Looks like low angle, high velocity. 532 00:20:40,531 --> 00:20:42,533 They must have been flying level. 533 00:20:42,616 --> 00:20:43,993 CFIT? 534 00:20:44,076 --> 00:20:46,537 Looks like it. 535 00:20:44,076 --> 00:20:46,537 Looks like it. 536 00:20:46,620 --> 00:20:49,665 They quickly recognize this incident as a controlled 537 00:20:49,749 --> 00:20:53,335 flight into terrain, or CFIT. 538 00:20:49,749 --> 00:20:53,335 flight into terrain, or CFIT. 539 00:20:53,419 --> 00:20:56,714 What was the altitude where they hit? 540 00:20:56,797 --> 00:21:01,719 1,795 feet. 541 00:20:56,797 --> 00:21:01,719 1,795 feet. 542 00:21:01,802 --> 00:21:03,679 And Pico Alto? 543 00:21:03,763 --> 00:21:05,681 What does the Jefferson chart show? 544 00:21:03,763 --> 00:21:05,681 What does the Jefferson chart show? 545 00:21:05,723 --> 00:21:09,727 It's listed as 1,936 feet. 546 00:21:09,810 --> 00:21:12,813 They struck the mountain 140 feet below what 547 00:21:09,810 --> 00:21:12,813 They struck the mountain 140 feet below what 548 00:21:12,855 --> 00:21:15,858 was listed on their chart. 549 00:21:15,900 --> 00:21:18,486 What were they doing so low? 550 00:21:18,527 --> 00:21:23,073 The possibilities were one, the crew was off course. 551 00:21:18,527 --> 00:21:23,073 The possibilities were one, the crew was off course. 552 00:21:23,157 --> 00:21:25,242 Two, there was an altitude error. 553 00:21:25,326 --> 00:21:27,661 It was our job to find out which of those 554 00:21:27,703 --> 00:21:30,873 would explain the accident. 555 00:21:27,703 --> 00:21:30,873 would explain the accident. 556 00:21:30,915 --> 00:21:32,958 What's the minimum sector altitude? 557 00:21:33,042 --> 00:21:36,420 3,000 feet. 558 00:21:33,042 --> 00:21:36,420 3,000 feet. 559 00:21:36,504 --> 00:21:38,547 The minimum sector altitude is 560 00:21:38,631 --> 00:21:40,883 at least 1,000 feet above all terrain 561 00:21:38,631 --> 00:21:40,883 at least 1,000 feet above all terrain 562 00:21:40,966 --> 00:21:43,594 within 25 miles of the airport. 563 00:21:43,677 --> 00:21:45,805 There's plenty of room. 564 00:21:45,888 --> 00:21:49,558 Why did these guys descend so low when they knew by the charts 565 00:21:49,642 --> 00:21:52,728 that the minimum altitude was 3,000 feet 566 00:21:49,642 --> 00:21:52,728 that the minimum altitude was 3,000 feet 567 00:21:52,812 --> 00:21:56,732 and there was a mountain there? 568 00:21:56,816 --> 00:21:59,026 What was the minimum sector altitude you gave them? 569 00:21:56,816 --> 00:21:59,026 What was the minimum sector altitude you gave them? 570 00:22:01,904 --> 00:22:04,365 The team checks to see if the air traffic 571 00:22:01,904 --> 00:22:04,365 The team checks to see if the air traffic 572 00:22:04,406 --> 00:22:05,866 controller made an error. 573 00:22:08,577 --> 00:22:09,662 3,000 feet. 574 00:22:09,745 --> 00:22:11,789 You're sure? 575 00:22:09,745 --> 00:22:11,789 You're sure? 576 00:22:11,872 --> 00:22:14,166 Yeah, I even made a note of it on my flight strip. 577 00:22:17,837 --> 00:22:19,380 He was perfectly calm. 578 00:22:19,421 --> 00:22:20,923 He had a normal behavior. 579 00:22:20,965 --> 00:22:23,467 He thought he had done a good job. 580 00:22:20,965 --> 00:22:23,467 He thought he had done a good job. 581 00:22:23,551 --> 00:22:25,886 Were they advised to use the ILS? 582 00:22:25,928 --> 00:22:26,595 Yes. 583 00:22:29,181 --> 00:22:31,433 Expect ILS approach. 584 00:22:31,475 --> 00:22:37,189 Runway one niner, report reaching 3,000. 585 00:22:31,475 --> 00:22:37,189 Runway one niner, report reaching 3,000. 586 00:22:37,273 --> 00:22:39,233 I couldn't find anything that explains 587 00:22:39,275 --> 00:22:41,110 what happened from his part. 588 00:22:39,275 --> 00:22:41,110 what happened from his part. 589 00:22:41,151 --> 00:22:43,946 Maybe the altitude alert survived. 590 00:22:44,029 --> 00:22:45,823 Let's take a look. 591 00:22:45,906 --> 00:22:48,951 The altitude alert sounds a warning when the plane 592 00:22:49,034 --> 00:22:52,454 approaches a preset altitude. 593 00:22:49,034 --> 00:22:52,454 approaches a preset altitude. 594 00:22:57,626 --> 00:23:02,965 Investigators discover that the altitude was set to 2,000 feet, 595 00:22:57,626 --> 00:23:02,965 Investigators discover that the altitude was set to 2,000 feet, 596 00:23:03,048 --> 00:23:07,011 a thousand feet below the required altitude of 3,000 feet. 597 00:23:03,048 --> 00:23:07,011 a thousand feet below the required altitude of 3,000 feet. 598 00:23:07,094 --> 00:23:09,305 This shocked all of us. 599 00:23:09,346 --> 00:23:11,765 We just couldn't believe it, how that could happen. 600 00:23:09,346 --> 00:23:11,765 We just couldn't believe it, how that could happen. 601 00:23:14,810 --> 00:23:17,313 They hope the cockpit voice recorder will reveal 602 00:23:14,810 --> 00:23:17,313 They hope the cockpit voice recorder will reveal 603 00:23:17,396 --> 00:23:20,065 why the first officer input the wrong data 604 00:23:20,149 --> 00:23:21,650 into the altitude alert. 605 00:23:25,571 --> 00:23:27,823 Independent 1851, roger. 606 00:23:27,865 --> 00:23:33,412 You're cleared to 3,000 on QNH 1027. 607 00:23:27,865 --> 00:23:33,412 You're cleared to 3,000 on QNH 1027. 608 00:23:33,495 --> 00:23:36,373 Clear to 2,000. 609 00:23:33,495 --> 00:23:36,373 Clear to 2,000. 610 00:23:36,457 --> 00:23:38,918 Did the first officer just say 2,000? 611 00:23:39,001 --> 00:23:45,007 Maybe he heard "to 3,000" and mistook it for 2,000. 612 00:23:39,001 --> 00:23:45,007 Maybe he heard "to 3,000" and mistook it for 2,000. 613 00:23:45,049 --> 00:23:49,178 The controller should have corrected him too, but doesn't. 614 00:23:45,049 --> 00:23:49,178 The controller should have corrected him too, but doesn't. 615 00:23:49,261 --> 00:23:50,554 Why? 616 00:23:50,638 --> 00:23:51,430 Hang on a second. 617 00:23:56,101 --> 00:23:58,520 The first officer's read back of 2,000 feet 618 00:23:56,101 --> 00:23:58,520 The first officer's read back of 2,000 feet 619 00:23:58,604 --> 00:24:00,272 isn't in the controller's transcript. 620 00:24:00,356 --> 00:24:02,274 So he never heard it? 621 00:24:02,358 --> 00:24:03,692 How is that possible? 622 00:24:09,156 --> 00:24:12,076 Investigators compare the transcripts from the plane 623 00:24:09,156 --> 00:24:12,076 Investigators compare the transcripts from the plane 624 00:24:12,159 --> 00:24:13,369 to those from the tower. 625 00:24:16,664 --> 00:24:17,539 Hang on. 626 00:24:26,507 --> 00:24:27,925 They were talking at the same time. 627 00:24:26,507 --> 00:24:27,925 They were talking at the same time. 628 00:24:28,008 --> 00:24:29,093 Yeah. 629 00:24:29,176 --> 00:24:32,554 They canceled each other out. 630 00:24:32,596 --> 00:24:42,356 You're clear to 3,000 feet on QNH 1027, runway one niner. 631 00:24:32,596 --> 00:24:42,356 You're clear to 3,000 feet on QNH 1027, runway one niner. 632 00:24:32,596 --> 00:24:42,356 You're clear to 3,000 feet on QNH 1027, runway one niner. 633 00:24:44,358 --> 00:24:47,069 We're clear to 2,000 feet and... 634 00:24:44,358 --> 00:24:47,069 We're clear to 2,000 feet and... 635 00:24:47,111 --> 00:24:48,320 Runway one niner. 636 00:24:48,404 --> 00:24:49,113 1027. 637 00:24:49,196 --> 00:24:51,615 ...to 3,000. 638 00:24:51,699 --> 00:24:52,783 It was stunning. 639 00:24:51,699 --> 00:24:52,783 It was stunning. 640 00:24:52,866 --> 00:24:56,620 We were stunned to finally understand 641 00:24:56,704 --> 00:25:00,582 how the two transmissions overlapped perfectly 642 00:24:56,704 --> 00:25:00,582 how the two transmissions overlapped perfectly 643 00:25:00,624 --> 00:25:02,459 to cancel each other out. 644 00:25:02,543 --> 00:25:05,963 I was an investigator for over 30 years with the NTSB. 645 00:25:02,543 --> 00:25:05,963 I was an investigator for over 30 years with the NTSB. 646 00:25:06,046 --> 00:25:08,173 I've never encountered anything like this before, 647 00:25:08,257 --> 00:25:11,593 and I never encountered anything like this afterwards. 648 00:25:08,257 --> 00:25:11,593 and I never encountered anything like this afterwards. 649 00:25:11,677 --> 00:25:13,303 But this discovery alone 650 00:25:13,387 --> 00:25:16,974 isn't enough to explain why the plane was so low when 651 00:25:13,387 --> 00:25:16,974 isn't enough to explain why the plane was so low when 652 00:25:17,057 --> 00:25:18,559 it crashed into the mountain. 653 00:25:22,229 --> 00:25:23,772 So the controller doesn't hear it. 654 00:25:23,814 --> 00:25:25,315 Investigators have discovered 655 00:25:25,399 --> 00:25:28,694 that critical communications about flight 1851's 656 00:25:25,399 --> 00:25:28,694 that critical communications about flight 1851's 657 00:25:28,777 --> 00:25:32,448 required altitude were missed because of overlapping radio 658 00:25:32,531 --> 00:25:33,157 calls with. 659 00:25:33,240 --> 00:25:34,033 One niner. 660 00:25:33,240 --> 00:25:34,033 One niner. 661 00:25:34,116 --> 00:25:34,825 1027. 662 00:25:34,908 --> 00:25:36,160 ...to 3,000. 663 00:25:36,243 --> 00:25:37,327 But there's still another question 664 00:25:37,411 --> 00:25:38,287 that worries them. 665 00:25:38,370 --> 00:25:40,039 Something doesn't line up. 666 00:25:38,370 --> 00:25:40,039 Something doesn't line up. 667 00:25:44,460 --> 00:25:50,049 The plane's altimeter alert was incorrectly set to 2,000 feet. 668 00:25:44,460 --> 00:25:50,049 The plane's altimeter alert was incorrectly set to 2,000 feet. 669 00:25:50,132 --> 00:25:52,301 Even at that altitude, they would have cleared 670 00:25:50,132 --> 00:25:52,301 Even at that altitude, they would have cleared 671 00:25:52,342 --> 00:25:55,804 the ridge by some 200 feet. 672 00:25:55,846 --> 00:25:58,390 What else affects altitude? 673 00:25:55,846 --> 00:25:58,390 What else affects altitude? 674 00:25:58,474 --> 00:25:59,308 QNH. 675 00:26:02,770 --> 00:26:05,439 QNH is an air pressure value pilots 676 00:26:02,770 --> 00:26:05,439 QNH is an air pressure value pilots 677 00:26:05,481 --> 00:26:07,983 input so their altimeter can accurately 678 00:26:08,025 --> 00:26:09,359 measure the plane's height. 679 00:26:09,443 --> 00:26:13,363 That value can change with weather conditions. 680 00:26:09,443 --> 00:26:13,363 That value can change with weather conditions. 681 00:26:13,447 --> 00:26:17,743 If the altimeter is set to a higher QNH than is actual, 682 00:26:13,447 --> 00:26:17,743 If the altimeter is set to a higher QNH than is actual, 683 00:26:17,826 --> 00:26:21,288 the aircraft will actually be lower than what the altimeter is 684 00:26:21,330 --> 00:26:24,083 telling the pilots. 685 00:26:21,330 --> 00:26:24,083 telling the pilots. 686 00:26:24,166 --> 00:26:31,006 Says here they were given a QNH of 1019 at 1:44 PM. 687 00:26:24,166 --> 00:26:31,006 Says here they were given a QNH of 1019 at 1:44 PM. 688 00:26:31,090 --> 00:26:37,679 Then they were given a reading of 1027 at 1:56 PM. 689 00:26:31,090 --> 00:26:37,679 Then they were given a reading of 1027 at 1:56 PM. 690 00:26:37,763 --> 00:26:39,890 Investigators calculate the change 691 00:26:37,763 --> 00:26:39,890 Investigators calculate the change 692 00:26:39,973 --> 00:26:43,852 in altitude between the two different settings. 693 00:26:43,894 --> 00:26:47,606 That QNH brought them at least 200 feet below 2,000. 694 00:26:43,894 --> 00:26:47,606 That QNH brought them at least 200 feet below 2,000. 695 00:26:47,689 --> 00:26:48,649 Right into the mountain. 696 00:26:57,116 --> 00:26:58,617 They asked the controller 697 00:26:57,116 --> 00:26:58,617 They asked the controller 698 00:26:58,700 --> 00:27:01,328 about the two different settings he gave to the pilots. 699 00:27:03,914 --> 00:27:07,417 1019 was on the MET report. 700 00:27:07,501 --> 00:27:10,754 But 12 minutes later, when you gave them the 3,000 foot 701 00:27:07,501 --> 00:27:10,754 But 12 minutes later, when you gave them the 3,000 foot 702 00:27:10,838 --> 00:27:16,260 clearance, you said "QNH 1027." 703 00:27:10,838 --> 00:27:16,260 clearance, you said "QNH 1027." 704 00:27:19,680 --> 00:27:20,973 Sorry. 705 00:27:21,056 --> 00:27:22,057 I don't know where I got that second number. 706 00:27:21,056 --> 00:27:22,057 I don't know where I got that second number. 707 00:27:26,019 --> 00:27:28,772 Investigators turn to the CVR 708 00:27:26,019 --> 00:27:28,772 Investigators turn to the CVR 709 00:27:28,856 --> 00:27:32,317 to see if the pilots caught the controller's mistake. 710 00:27:32,401 --> 00:27:37,156 After the first officer gets the minimum descent altitude wrong, 711 00:27:32,401 --> 00:27:37,156 After the first officer gets the minimum descent altitude wrong, 712 00:27:37,239 --> 00:27:39,658 he questions the QNH. 713 00:27:39,741 --> 00:27:40,951 Is that what they said? 714 00:27:39,741 --> 00:27:40,951 Is that what they said? 715 00:27:41,034 --> 00:27:42,494 1027 on the millibars? 716 00:27:42,578 --> 00:27:45,247 Yep. 717 00:27:45,289 --> 00:27:46,915 He was right to question it. 718 00:27:45,289 --> 00:27:46,915 He was right to question it. 719 00:27:46,999 --> 00:27:48,458 But the captain just dismisses it. 720 00:27:48,542 --> 00:27:50,127 Thank you. 721 00:27:50,210 --> 00:27:54,715 And the first officer just accepts it. 722 00:27:50,210 --> 00:27:54,715 And the first officer just accepts it. 723 00:27:54,756 --> 00:27:57,801 Because of the different experience levels, 724 00:27:57,885 --> 00:28:00,304 because of the prominence and assertiveness 725 00:28:00,387 --> 00:28:03,640 with which the captain said it, shut off any discussion. 726 00:28:03,724 --> 00:28:07,186 Makes you wonder what else these guys missed. 727 00:28:03,724 --> 00:28:07,186 Makes you wonder what else these guys missed. 728 00:28:07,269 --> 00:28:10,272 Investigators return to the cockpit voice recording 729 00:28:07,269 --> 00:28:10,272 Investigators return to the cockpit voice recording 730 00:28:10,314 --> 00:28:12,816 to hear how the pilots briefed each other 731 00:28:12,900 --> 00:28:15,652 before approaching the landing. 732 00:28:15,736 --> 00:28:18,363 Altimeters, set and cross-check. 733 00:28:15,736 --> 00:28:18,363 Altimeters, set and cross-check. 734 00:28:18,447 --> 00:28:19,781 Set and cross-checked. 735 00:28:19,823 --> 00:28:21,742 Seat belts and shoulder harness. 736 00:28:26,246 --> 00:28:27,998 Secured. 737 00:28:26,246 --> 00:28:27,998 Secured. 738 00:28:28,081 --> 00:28:29,333 We're having fun now. 739 00:28:29,416 --> 00:28:32,002 Hey, hey. 740 00:28:32,085 --> 00:28:33,545 That's it? 741 00:28:33,629 --> 00:28:36,381 Stop the tape. 742 00:28:33,629 --> 00:28:36,381 Stop the tape. 743 00:28:36,465 --> 00:28:39,927 They don't even mention the minimum descent altitude. 744 00:28:36,465 --> 00:28:39,927 They don't even mention the minimum descent altitude. 745 00:28:39,968 --> 00:28:41,803 Or Pico Alto, here. 746 00:28:46,475 --> 00:28:48,602 The lack of detail is shocking. 747 00:28:52,606 --> 00:28:54,191 Had they done the approach of briefing 748 00:28:54,274 --> 00:28:57,486 and reviewed the information and articulated the information 749 00:28:57,569 --> 00:29:01,156 as required, it's highly unlikely, 750 00:28:57,569 --> 00:29:01,156 as required, it's highly unlikely, 751 00:29:01,198 --> 00:29:05,410 in my opinion, that they would have struck the mountain. 752 00:29:01,198 --> 00:29:05,410 in my opinion, that they would have struck the mountain. 753 00:29:05,494 --> 00:29:06,995 Starting to pass through the layers. 754 00:29:11,875 --> 00:29:12,709 Pull up. 755 00:29:12,793 --> 00:29:13,543 Terrain, terrain. 756 00:29:14,670 --> 00:29:15,671 Pull up. 757 00:29:15,712 --> 00:29:17,798 The captain is ultimately responsible as the pilot 758 00:29:15,712 --> 00:29:17,798 The captain is ultimately responsible as the pilot 759 00:29:17,839 --> 00:29:19,258 in command. 760 00:29:19,341 --> 00:29:21,343 But each crew member failed in that respect. 761 00:29:21,385 --> 00:29:22,886 Pull up. 762 00:29:21,385 --> 00:29:22,886 Pull up. 763 00:29:25,138 --> 00:29:26,139 Pull up. 764 00:29:32,521 --> 00:29:36,066 Investigators conclude that the pilots failed to follow 765 00:29:32,521 --> 00:29:36,066 Investigators conclude that the pilots failed to follow 766 00:29:36,149 --> 00:29:39,069 procedures that would have caught the bad data provided 767 00:29:39,152 --> 00:29:42,906 by the air traffic controller. 768 00:29:39,152 --> 00:29:42,906 by the air traffic controller. 769 00:29:42,990 --> 00:29:45,450 One doesn't necessarily completely 770 00:29:45,534 --> 00:29:48,578 trust any system or any data resource. 771 00:29:45,534 --> 00:29:48,578 trust any system or any data resource. 772 00:29:48,662 --> 00:29:52,708 The information that one receives, either from 773 00:29:48,662 --> 00:29:52,708 The information that one receives, either from 774 00:29:52,791 --> 00:29:55,043 one's senses, or from the instruments of the aircraft, 775 00:29:55,127 --> 00:29:56,920 or from outside navigational aids, 776 00:29:57,004 --> 00:30:00,382 has to be balanced with one's own experience and judgment. 777 00:29:57,004 --> 00:30:00,382 has to be balanced with one's own experience and judgment. 778 00:30:03,552 --> 00:30:06,513 When bad data slips into the second-by-second 779 00:30:03,552 --> 00:30:06,513 When bad data slips into the second-by-second 780 00:30:06,555 --> 00:30:11,018 calculations that a pilot makes, the consequences can be tragic. 781 00:30:06,555 --> 00:30:11,018 calculations that a pilot makes, the consequences can be tragic. 782 00:30:17,524 --> 00:30:20,068 Gregorio Luperón International Airport 783 00:30:20,152 --> 00:30:21,361 in the Dominican Republic. 784 00:30:25,699 --> 00:30:28,535 Passengers on board Bergen Air Flight 301 785 00:30:25,699 --> 00:30:28,535 Passengers on board Bergen Air Flight 301 786 00:30:28,577 --> 00:30:31,413 have a nine-hour flight to Frankfurt ahead of them. 787 00:30:34,374 --> 00:30:35,625 Cabin crew, take your seats. 788 00:30:35,709 --> 00:30:38,170 Ready for takeoff. 789 00:30:38,253 --> 00:30:39,963 Exterior lights. 790 00:30:38,253 --> 00:30:39,963 Exterior lights. 791 00:30:40,047 --> 00:30:42,466 The pilots prepare their Boeing 757 for takeoff. 792 00:30:42,549 --> 00:30:43,759 Checked. 793 00:30:43,800 --> 00:30:45,052 First officer, Aykut Gergin, 794 00:30:45,093 --> 00:30:48,138 has fewer than 75 hours in the plane. 795 00:30:45,093 --> 00:30:48,138 has fewer than 75 hours in the plane. 796 00:30:48,221 --> 00:30:48,972 Thank you. 797 00:30:49,056 --> 00:30:50,599 Ready for takeoff. 798 00:30:50,640 --> 00:30:53,352 Captain Ahmet Erdem is one of Birgenair's most 799 00:30:50,640 --> 00:30:53,352 Captain Ahmet Erdem is one of Birgenair's most 800 00:30:53,435 --> 00:30:55,187 senior pilots. 801 00:30:55,270 --> 00:30:58,273 Alpha Lima Whisky 301, ready for takeoff. 802 00:30:55,270 --> 00:30:58,273 Alpha Lima Whisky 301, ready for takeoff. 803 00:30:58,357 --> 00:30:59,816 OPERATOR 2:301, cleared for takeoff. 804 00:30:59,900 --> 00:31:01,443 Runway 08. 805 00:31:01,526 --> 00:31:03,653 Cleared for takeoff, runway 08301. 806 00:31:03,737 --> 00:31:05,155 Thank you. 807 00:31:03,737 --> 00:31:05,155 Thank you. 808 00:31:05,238 --> 00:31:06,865 Muhlis Evrenosoglu is the relief pilot. 809 00:31:06,948 --> 00:31:07,866 A good flight. 810 00:31:07,949 --> 00:31:08,742 Good flight. 811 00:31:08,784 --> 00:31:10,660 Good flight. 812 00:31:08,784 --> 00:31:10,660 Good flight. 813 00:31:10,744 --> 00:31:12,037 Power set. 814 00:31:12,120 --> 00:31:12,954 Clear, checked. 815 00:31:16,083 --> 00:31:17,876 80 knots. 816 00:31:17,959 --> 00:31:19,878 Check. 817 00:31:19,961 --> 00:31:21,880 My airspeed indicator is not working. 818 00:31:19,961 --> 00:31:21,880 My airspeed indicator is not working. 819 00:31:25,133 --> 00:31:27,511 The captain's airspeed should read the same 820 00:31:27,594 --> 00:31:28,845 as his first officer's. 821 00:31:27,594 --> 00:31:28,845 as his first officer's. 822 00:31:28,929 --> 00:31:30,972 120. 823 00:31:31,014 --> 00:31:33,016 But it doesn't. 824 00:31:33,100 --> 00:31:33,850 Is yours working? 825 00:31:33,934 --> 00:31:34,810 Yes, sir. 826 00:31:38,772 --> 00:31:40,023 You tell me. 827 00:31:38,772 --> 00:31:40,023 You tell me. 828 00:31:40,107 --> 00:31:41,650 Erdem instructs his first officer 829 00:31:41,733 --> 00:31:44,403 to call out when the plane reaches takeoff speed. 830 00:31:44,486 --> 00:31:45,320 V1. 831 00:31:51,118 --> 00:31:52,619 Rotate. 832 00:31:51,118 --> 00:31:52,619 Rotate. 833 00:32:00,502 --> 00:32:03,880 Shortly after takeoff, the captain's airspeed indicator 834 00:32:00,502 --> 00:32:03,880 Shortly after takeoff, the captain's airspeed indicator 835 00:32:03,964 --> 00:32:06,925 appears to be functioning normally. 836 00:32:07,008 --> 00:32:08,427 Climb thrust. 837 00:32:08,510 --> 00:32:09,845 Climb thrust. 838 00:32:12,472 --> 00:32:14,891 One minute, 30 seconds into the flight, 839 00:32:14,975 --> 00:32:17,727 the crew engages the autopilot. 840 00:32:14,975 --> 00:32:17,727 the crew engages the autopilot. 841 00:32:17,811 --> 00:32:20,564 Central autopilot on, please. 842 00:32:20,647 --> 00:32:22,566 Central autopilot, as command. 843 00:32:20,647 --> 00:32:22,566 Central autopilot, as command. 844 00:32:22,649 --> 00:32:23,567 Thank you. 845 00:32:28,155 --> 00:32:31,408 Then the computer reports a problem. 846 00:32:31,491 --> 00:32:32,868 Rudder ratio. 847 00:32:32,909 --> 00:32:34,619 Mach airspeed trim. 848 00:32:32,909 --> 00:32:34,619 Mach airspeed trim. 849 00:32:34,703 --> 00:32:37,789 The alert warns that the plane is traveling too fast. 850 00:32:37,873 --> 00:32:40,125 Yes, trim. 851 00:32:37,873 --> 00:32:40,125 Yes, trim. 852 00:32:40,208 --> 00:32:41,501 Something's wrong here. 853 00:32:44,337 --> 00:32:46,256 Captain Erdem's airspeed indicator 854 00:32:44,337 --> 00:32:46,256 Captain Erdem's airspeed indicator 855 00:32:46,339 --> 00:32:50,385 shows the plane traveling at 325 knots. 856 00:32:50,469 --> 00:32:52,387 But the first officer's indicates 857 00:32:50,469 --> 00:32:52,387 But the first officer's indicates 858 00:32:52,429 --> 00:32:53,722 the plane going much slower. 859 00:32:57,225 --> 00:33:01,146 Mine shows only 200 now and decreasing, sir. 860 00:32:57,225 --> 00:33:01,146 Mine shows only 200 now and decreasing, sir. 861 00:33:01,229 --> 00:33:04,232 Both of them are wrong. 862 00:33:01,229 --> 00:33:04,232 Both of them are wrong. 863 00:33:04,274 --> 00:33:06,943 Now, a far more serious warning sounds. 864 00:33:11,323 --> 00:33:13,867 This alarm indicates the plane is 865 00:33:13,909 --> 00:33:18,121 approaching the maximum speed at which it was designed to fly. 866 00:33:13,909 --> 00:33:18,121 approaching the maximum speed at which it was designed to fly. 867 00:33:18,205 --> 00:33:22,918 Now it's 350, yes? 868 00:33:18,205 --> 00:33:22,918 Now it's 350, yes? 869 00:33:22,959 --> 00:33:25,420 Captain Erdem decides to do what the alerts 870 00:33:25,462 --> 00:33:29,132 tell him to do, slow down. 871 00:33:25,462 --> 00:33:29,132 tell him to do, slow down. 872 00:33:29,216 --> 00:33:31,301 And let's take that like this. 873 00:33:35,472 --> 00:33:38,475 The result is terrifying. 874 00:33:38,558 --> 00:33:39,601 God, god. 875 00:33:41,645 --> 00:33:44,856 Shortly after takeoff, Birgenair Flight 301 876 00:33:44,940 --> 00:33:47,442 is in trouble. 877 00:33:44,940 --> 00:33:47,442 is in trouble. 878 00:33:47,526 --> 00:33:50,403 God, god, god. 879 00:33:50,445 --> 00:33:52,656 The cockpit fills with the ominous sound 880 00:33:50,445 --> 00:33:52,656 The cockpit fills with the ominous sound 881 00:33:52,739 --> 00:33:53,740 of the stick shaker. 882 00:33:57,118 --> 00:34:02,332 It means that the airplane is about to attain a speed so low 883 00:33:57,118 --> 00:34:02,332 It means that the airplane is about to attain a speed so low 884 00:34:02,415 --> 00:34:05,168 that it cannot sustain flight. 885 00:34:02,415 --> 00:34:05,168 that it cannot sustain flight. 886 00:34:11,550 --> 00:34:13,218 The plane's attitude direction 887 00:34:13,301 --> 00:34:17,222 indicator shows that its nose is pointing dangerously high. 888 00:34:13,301 --> 00:34:17,222 indicator shows that its nose is pointing dangerously high. 889 00:34:17,305 --> 00:34:18,807 ADI. 890 00:34:24,854 --> 00:34:28,525 Suddenly, the plane rolls hard to the right 891 00:34:24,854 --> 00:34:28,525 Suddenly, the plane rolls hard to the right 892 00:34:28,608 --> 00:34:30,235 and begins to dive. 893 00:34:30,318 --> 00:34:31,236 Thrust levers. 894 00:34:31,319 --> 00:34:32,070 Thrust. 895 00:34:40,120 --> 00:34:40,912 Pull up! 896 00:34:44,165 --> 00:34:46,001 Oh, what's happening? 897 00:34:44,165 --> 00:34:46,001 Oh, what's happening? 898 00:34:50,338 --> 00:34:53,633 Birgenair Flight 301 vanishes from radar. 899 00:34:50,338 --> 00:34:53,633 Birgenair Flight 301 vanishes from radar. 900 00:34:57,971 --> 00:34:59,472 No survivors are found. 901 00:35:02,517 --> 00:35:05,937 The Dominican Republic's Air Traffic Accident Investigation 902 00:35:02,517 --> 00:35:05,937 The Dominican Republic's Air Traffic Accident Investigation 903 00:35:06,021 --> 00:35:09,399 Bureau asks the US National Transportation Safety 904 00:35:09,482 --> 00:35:11,526 Board to assist in their investigation 905 00:35:09,482 --> 00:35:11,526 Board to assist in their investigation 906 00:35:11,568 --> 00:35:16,406 of the downed Boeing 757. 907 00:35:11,568 --> 00:35:16,406 of the downed Boeing 757. 908 00:35:16,489 --> 00:35:18,158 Any signal from the recorders? 909 00:35:23,955 --> 00:35:25,874 It takes three weeks to recover 910 00:35:25,915 --> 00:35:27,709 Flight 301's black boxes. 911 00:35:31,671 --> 00:35:36,217 That flight data recorder was our key. 912 00:35:31,671 --> 00:35:36,217 That flight data recorder was our key. 913 00:35:36,259 --> 00:35:38,887 Investigators immediately noticed something 914 00:35:38,928 --> 00:35:40,889 unusual about the flight. 915 00:35:38,928 --> 00:35:40,889 unusual about the flight. 916 00:35:40,930 --> 00:35:44,184 15 degrees pitch, nose up. 917 00:35:44,225 --> 00:35:46,269 Seems high. 918 00:35:44,225 --> 00:35:46,269 Seems high. 919 00:35:46,353 --> 00:35:48,938 He's almost the maximum. 920 00:35:49,022 --> 00:35:51,941 Shortly after the autopilot is switched on, 921 00:35:49,022 --> 00:35:51,941 Shortly after the autopilot is switched on, 922 00:35:52,025 --> 00:35:55,445 the plane's nose pitches upward. 923 00:35:55,528 --> 00:35:58,615 They also see that the indicated airspeed is 924 00:35:55,528 --> 00:35:58,615 They also see that the indicated airspeed is 925 00:35:58,698 --> 00:36:00,617 much higher than it should be. 926 00:36:00,700 --> 00:36:03,620 350 knots. 927 00:36:03,703 --> 00:36:06,414 It can't be right. 928 00:36:03,703 --> 00:36:06,414 It can't be right. 929 00:36:06,498 --> 00:36:07,957 They focus their attention 930 00:36:08,041 --> 00:36:10,627 on the sensor that feeds airspeed information 931 00:36:08,041 --> 00:36:10,627 on the sensor that feeds airspeed information 932 00:36:10,710 --> 00:36:13,213 to the gauges, the pitot tube. 933 00:36:16,424 --> 00:36:20,011 When the plane travels forward, an increase in air pressure 934 00:36:20,095 --> 00:36:23,515 inside the pitot tube causes the airspeed indicators 935 00:36:20,095 --> 00:36:23,515 inside the pitot tube causes the airspeed indicators 936 00:36:23,598 --> 00:36:24,891 needle to move. 937 00:36:24,933 --> 00:36:27,394 But if a pitot tube becomes blocked, 938 00:36:27,435 --> 00:36:32,065 it can send faulty readings to the plane's gauges. 939 00:36:27,435 --> 00:36:32,065 it can send faulty readings to the plane's gauges. 940 00:36:32,107 --> 00:36:35,652 We started carefully looking at what could cause 941 00:36:32,107 --> 00:36:35,652 We started carefully looking at what could cause 942 00:36:35,735 --> 00:36:38,363 that kind of thing to happen. 943 00:36:38,446 --> 00:36:41,157 Regulations state that any time a plane 944 00:36:38,446 --> 00:36:41,157 Regulations state that any time a plane 945 00:36:41,241 --> 00:36:44,160 will be on the ground for an extended period of time, 946 00:36:44,244 --> 00:36:47,497 pitot tube covers must be placed on the tubes 947 00:36:44,244 --> 00:36:47,497 pitot tube covers must be placed on the tubes 948 00:36:47,580 --> 00:36:52,210 to prevent blockage, usually by dirt or ice. 949 00:36:47,580 --> 00:36:52,210 to prevent blockage, usually by dirt or ice. 950 00:36:52,293 --> 00:36:54,546 Records indicate that the plane sat 951 00:36:54,629 --> 00:36:57,841 on the tarmac in Puerto Plata for 25 days 952 00:36:57,924 --> 00:37:02,178 before taking off for Frankfurt. 953 00:36:57,924 --> 00:37:02,178 before taking off for Frankfurt. 954 00:37:02,262 --> 00:37:04,013 I like to ask you some question 955 00:37:02,262 --> 00:37:04,013 I like to ask you some question 956 00:37:04,097 --> 00:37:05,682 about the Birgenair airplane. 957 00:37:05,765 --> 00:37:08,184 Investigators wonder if mechanics 958 00:37:08,268 --> 00:37:12,021 neglected to cover the pitot tubes after maintenance. 959 00:37:08,268 --> 00:37:12,021 neglected to cover the pitot tubes after maintenance. 960 00:37:12,105 --> 00:37:15,525 Did you put the pitot covers back on them when 961 00:37:15,608 --> 00:37:17,318 the maintenance was finished? 962 00:37:15,608 --> 00:37:17,318 the maintenance was finished? 963 00:37:17,402 --> 00:37:19,112 It didn't have any covers with it. 964 00:37:19,154 --> 00:37:21,823 We didn't take any off, and we didn't put any on. 965 00:37:29,372 --> 00:37:31,583 And that's when we discovered that the potatoes had 966 00:37:31,666 --> 00:37:34,669 not been covered for the 25 days that the aircraft 967 00:37:31,666 --> 00:37:34,669 not been covered for the 25 days that the aircraft 968 00:37:34,711 --> 00:37:39,215 remained parked at the international airport in Puerto Plata. 969 00:37:39,299 --> 00:37:42,761 The investigation team concludes that in that time, 970 00:37:39,299 --> 00:37:42,761 The investigation team concludes that in that time, 971 00:37:42,844 --> 00:37:45,722 some sort of blockage developed in the pitot tube 972 00:37:45,805 --> 00:37:47,265 on the captain's side. 973 00:37:45,805 --> 00:37:47,265 on the captain's side. 974 00:37:47,348 --> 00:37:48,850 Nobody knows for sure. 975 00:37:48,892 --> 00:37:52,771 The evidence is 7,000 down in the Atlantic Ocean. 976 00:37:48,892 --> 00:37:52,771 The evidence is 7,000 down in the Atlantic Ocean. 977 00:37:52,854 --> 00:37:55,064 A blocked pitot tube could have given 978 00:37:55,148 --> 00:37:57,859 the pilots bad data in the form of conflicting 979 00:37:57,901 --> 00:38:00,069 airspeed readings. 980 00:37:57,901 --> 00:38:00,069 airspeed readings. 981 00:38:00,153 --> 00:38:04,783 But how could that lead to such a disaster? 982 00:38:00,153 --> 00:38:04,783 But how could that lead to such a disaster? 983 00:38:04,866 --> 00:38:07,118 And what we've got for you is a computer... 984 00:38:07,202 --> 00:38:09,454 Using information from the black boxes, 985 00:38:09,537 --> 00:38:13,625 the NTSB pieces together, the flight's last moments. 986 00:38:09,537 --> 00:38:13,625 the NTSB pieces together, the flight's last moments. 987 00:38:13,708 --> 00:38:16,544 The captain actually realized that his speed 988 00:38:13,708 --> 00:38:16,544 The captain actually realized that his speed 989 00:38:16,628 --> 00:38:17,921 indicator was not working. 990 00:38:18,004 --> 00:38:18,755 Is yours working? 991 00:38:18,838 --> 00:38:21,424 Yes, sir. 992 00:38:21,508 --> 00:38:23,635 The data shows that the problems 993 00:38:21,508 --> 00:38:23,635 The data shows that the problems 994 00:38:23,718 --> 00:38:28,097 on Birgenair Flight 301 began when the autopilot took over. 995 00:38:23,718 --> 00:38:28,097 on Birgenair Flight 301 began when the autopilot took over. 996 00:38:28,181 --> 00:38:30,266 Central autopilot on, please. 997 00:38:30,350 --> 00:38:31,434 Autopilot. 998 00:38:31,518 --> 00:38:33,228 Is it possible that the flight 999 00:38:33,269 --> 00:38:36,815 computer was just as confused about the airspeed as the crew? 1000 00:38:33,269 --> 00:38:36,815 computer was just as confused about the airspeed as the crew? 1001 00:38:36,898 --> 00:38:41,861 If so, how did that contribute to the crash? 1002 00:38:36,898 --> 00:38:41,861 If so, how did that contribute to the crash? 1003 00:38:41,903 --> 00:38:45,615 Right after the autopilot is engaged, 1004 00:38:45,698 --> 00:38:47,909 the plane's nose begins to rise. 1005 00:38:45,698 --> 00:38:47,909 the plane's nose begins to rise. 1006 00:38:47,951 --> 00:38:50,829 Investigators have discovered that Flight 301's 1007 00:38:50,912 --> 00:38:54,457 autopilot, sensing that the plane was traveling too fast, 1008 00:38:50,912 --> 00:38:54,457 autopilot, sensing that the plane was traveling too fast, 1009 00:38:54,541 --> 00:38:57,585 raised its nose to reduce speed. 1010 00:38:57,627 --> 00:39:00,421 It soon rises to 15 degrees. 1011 00:38:57,627 --> 00:39:00,421 It soon rises to 15 degrees. 1012 00:39:00,505 --> 00:39:03,424 Then it stays there. 1013 00:39:03,508 --> 00:39:05,552 The autopilot's a pretty smart guy. 1014 00:39:03,508 --> 00:39:05,552 The autopilot's a pretty smart guy. 1015 00:39:05,593 --> 00:39:08,429 He already knows he's got all the power that he's 1016 00:39:08,471 --> 00:39:11,182 going to get for the climb. 1017 00:39:08,471 --> 00:39:11,182 going to get for the climb. 1018 00:39:11,266 --> 00:39:15,562 The only thing for the autopilot to do is raise the nose. 1019 00:39:15,603 --> 00:39:17,522 But the autopilot is reacting 1020 00:39:15,603 --> 00:39:17,522 But the autopilot is reacting 1021 00:39:17,605 --> 00:39:22,652 to faulty airspeed information from the captain's pitot tube. 1022 00:39:17,605 --> 00:39:22,652 to faulty airspeed information from the captain's pitot tube. 1023 00:39:22,735 --> 00:39:25,113 The autopilot gets its data only 1024 00:39:25,154 --> 00:39:28,992 from the captain's pitot tube, the one that was blocked. 1025 00:39:25,154 --> 00:39:28,992 from the captain's pitot tube, the one that was blocked. 1026 00:39:29,075 --> 00:39:30,618 Moments later, it sends 1027 00:39:30,702 --> 00:39:32,453 out two different warnings. 1028 00:39:32,537 --> 00:39:35,206 Rudder ratio, mach airspeed trim. 1029 00:39:32,537 --> 00:39:35,206 Rudder ratio, mach airspeed trim. 1030 00:39:35,290 --> 00:39:37,876 And the airplane begins picking up warnings. 1031 00:39:37,959 --> 00:39:41,254 Rudder ratio, a variety of things that the airplane 1032 00:39:37,959 --> 00:39:41,254 Rudder ratio, a variety of things that the airplane 1033 00:39:41,296 --> 00:39:45,133 is sensing problems. 1034 00:39:45,216 --> 00:39:48,386 Investigators realized that Captain Erdem wrongly 1035 00:39:45,216 --> 00:39:48,386 Investigators realized that Captain Erdem wrongly 1036 00:39:48,469 --> 00:39:53,641 concluded that both airspeed indicators were malfunctioning. 1037 00:39:48,469 --> 00:39:53,641 concluded that both airspeed indicators were malfunctioning. 1038 00:39:53,683 --> 00:39:57,562 In fact, his first officer's gauge was always correct. 1039 00:39:57,645 --> 00:40:02,066 The plane was actually traveling much too slowly. 1040 00:39:57,645 --> 00:40:02,066 The plane was actually traveling much too slowly. 1041 00:40:02,150 --> 00:40:03,818 What can we do? 1042 00:40:03,860 --> 00:40:08,573 But that needle continued to climb around the clock face 1043 00:40:03,860 --> 00:40:08,573 But that needle continued to climb around the clock face 1044 00:40:08,656 --> 00:40:14,287 until it activated the overspeed warning. 1045 00:40:08,656 --> 00:40:14,287 until it activated the overspeed warning. 1046 00:40:14,329 --> 00:40:17,206 The autopilot system sends a warning that the plane 1047 00:40:14,329 --> 00:40:17,206 The autopilot system sends a warning that the plane 1048 00:40:17,290 --> 00:40:19,167 is traveling too fast. 1049 00:40:19,250 --> 00:40:21,794 But in reality, it's slowing down. 1050 00:40:25,381 --> 00:40:27,050 They're going slow. 1051 00:40:27,133 --> 00:40:30,553 They think they're going too fast, and confusion is set in. 1052 00:40:27,133 --> 00:40:30,553 They think they're going too fast, and confusion is set in. 1053 00:40:30,637 --> 00:40:31,721 Let's pull the airspeed. 1054 00:40:31,804 --> 00:40:33,348 Let's see. 1055 00:40:33,431 --> 00:40:34,724 That's when Captain Erdem 1056 00:40:33,431 --> 00:40:34,724 That's when Captain Erdem 1057 00:40:34,807 --> 00:40:37,268 makes the gravest error of all. 1058 00:40:37,352 --> 00:40:40,730 You can see that he now pulls back on his throttles. 1059 00:40:37,352 --> 00:40:40,730 You can see that he now pulls back on his throttles. 1060 00:40:40,813 --> 00:40:44,067 At the plane's already slow speed. 1061 00:40:50,156 --> 00:40:52,533 Pulling back on the throttles puts the plane 1062 00:40:50,156 --> 00:40:52,533 Pulling back on the throttles puts the plane 1063 00:40:52,575 --> 00:40:54,118 on the verge of stalling. 1064 00:40:54,202 --> 00:40:56,955 And that's when he gets the stick shaker. 1065 00:40:57,038 --> 00:40:59,499 God, god, god. 1066 00:40:57,038 --> 00:40:59,499 God, god, god. 1067 00:40:59,540 --> 00:41:01,084 The autopilot is programmed 1068 00:41:01,167 --> 00:41:04,712 to always disconnect when the stick shaker activates. 1069 00:41:01,167 --> 00:41:04,712 to always disconnect when the stick shaker activates. 1070 00:41:04,754 --> 00:41:08,257 With one warning telling him the plane is flying too fast 1071 00:41:08,341 --> 00:41:11,094 and another indicate it's flying too slow, 1072 00:41:08,341 --> 00:41:11,094 and another indicate it's flying too slow, 1073 00:41:11,177 --> 00:41:13,262 Captain Erdem is overwhelmed. 1074 00:41:15,848 --> 00:41:18,518 That airspeed warning horn combined 1075 00:41:15,848 --> 00:41:18,518 That airspeed warning horn combined 1076 00:41:18,559 --> 00:41:21,396 with a stick shaker was a tremendously 1077 00:41:21,437 --> 00:41:23,815 mind-boggling experience. 1078 00:41:21,437 --> 00:41:23,815 mind-boggling experience. 1079 00:41:23,898 --> 00:41:26,943 They're in direct opposition of each other, and two warnings 1080 00:41:27,026 --> 00:41:30,405 that you would never expect to get one right behind the other. 1081 00:41:27,026 --> 00:41:30,405 that you would never expect to get one right behind the other. 1082 00:41:30,446 --> 00:41:33,324 In response to the investigation's findings, 1083 00:41:33,408 --> 00:41:37,745 the FAA asks Boeing to change some of those warnings. 1084 00:41:33,408 --> 00:41:37,745 the FAA asks Boeing to change some of those warnings. 1085 00:41:37,829 --> 00:41:39,789 Those changes include the addition 1086 00:41:39,872 --> 00:41:42,750 of a new warning, which alerts both pilots when 1087 00:41:39,872 --> 00:41:42,750 of a new warning, which alerts both pilots when 1088 00:41:42,792 --> 00:41:45,837 their instruments disagree. 1089 00:41:45,920 --> 00:41:49,966 In addition, Boeing modifies its planes so that pilots can easily 1090 00:41:45,920 --> 00:41:49,966 In addition, Boeing modifies its planes so that pilots can easily 1091 00:41:50,049 --> 00:41:52,301 choose which pitot tube the autopilot 1092 00:41:50,049 --> 00:41:52,301 choose which pitot tube the autopilot 1093 00:41:52,385 --> 00:41:55,596 is using for airspeed readings. 1094 00:41:55,638 --> 00:41:59,517 You can't fly a modern aircraft without the proper data 1095 00:41:55,638 --> 00:41:59,517 You can't fly a modern aircraft without the proper data 1096 00:41:59,600 --> 00:42:02,145 because you don't just fly with a stick and a rudder 1097 00:42:02,228 --> 00:42:03,771 and look out the window anymore. 1098 00:42:03,813 --> 00:42:05,398 Your data is your flight. 1099 00:42:03,813 --> 00:42:05,398 Your data is your flight. 1100 00:42:08,901 --> 00:42:11,988 More than 1,400 Boeing planes worldwide are 1101 00:42:08,901 --> 00:42:11,988 More than 1,400 Boeing planes worldwide are 1102 00:42:12,071 --> 00:42:13,990 affected by the new directives. 1103 00:42:18,661 --> 00:42:21,122 One final question remains. 1104 00:42:21,205 --> 00:42:23,708 What blocked the plane's pitot tubes 1105 00:42:21,205 --> 00:42:23,708 What blocked the plane's pitot tubes 1106 00:42:23,791 --> 00:42:26,836 and caused the airspeed indicator to malfunction? 1107 00:42:26,919 --> 00:42:30,339 What's happening? 1108 00:42:26,919 --> 00:42:30,339 What's happening? 1109 00:42:30,423 --> 00:42:32,550 With Birgenair Flight 301's pitot 1110 00:42:32,633 --> 00:42:36,095 tubes lost in the ocean floor, investigators 1111 00:42:32,633 --> 00:42:36,095 tubes lost in the ocean floor, investigators 1112 00:42:36,137 --> 00:42:39,932 look at the area surrounding the airport in Puerto Plata 1113 00:42:39,974 --> 00:42:43,644 and think they found a likely suspect... 1114 00:42:43,728 --> 00:42:47,315 The mud dauber wasp. 1115 00:42:43,728 --> 00:42:47,315 The mud dauber wasp. 1116 00:42:53,946 --> 00:42:55,907 When a mud dauber is looking for an area 1117 00:42:55,990 --> 00:42:59,327 to build its nest, it's looking for a site, a place 1118 00:42:55,990 --> 00:42:59,327 to build its nest, it's looking for a site, a place 1119 00:42:59,368 --> 00:43:01,329 that's more or less tubular. 1120 00:43:07,627 --> 00:43:10,171 They didn't put covers on the pitot tubes. 1121 00:43:07,627 --> 00:43:10,171 They didn't put covers on the pitot tubes. 1122 00:43:10,213 --> 00:43:13,508 So there was an opportunity to get something like a mud 1123 00:43:13,591 --> 00:43:16,302 dauber in that pitot tube. 1124 00:43:13,591 --> 00:43:16,302 dauber in that pitot tube. 1125 00:43:18,763 --> 00:43:20,473 More than ever, aircraft 1126 00:43:20,515 --> 00:43:24,769 depend on complex flight computers for safe flight. 1127 00:43:20,515 --> 00:43:24,769 depend on complex flight computers for safe flight. 1128 00:43:24,852 --> 00:43:29,148 Even the smallest scrap of bad data can prove to be deadly. 1129 00:43:24,852 --> 00:43:29,148 Even the smallest scrap of bad data can prove to be deadly. 1130 00:43:34,904 --> 00:43:37,573 Aircraft and aircraft systems have become much more 1131 00:43:37,657 --> 00:43:39,408 sophisticated over the years. 1132 00:43:39,492 --> 00:43:42,411 But even with the most sophisticated aircraft, 1133 00:43:39,492 --> 00:43:42,411 But even with the most sophisticated aircraft, 1134 00:43:42,495 --> 00:43:45,456 it's essential and necessary for pilots 1135 00:43:45,540 --> 00:43:47,959 to know how to deal with those systems, 1136 00:43:45,540 --> 00:43:47,959 to know how to deal with those systems, 1137 00:43:48,042 --> 00:43:51,963 how to understand how they work, how to not use them if they're 1138 00:43:48,042 --> 00:43:51,963 how to understand how they work, how to not use them if they're 1139 00:43:52,046 --> 00:43:55,883 giving them bad data, and how to manage 1140 00:43:55,925 --> 00:43:58,427 whatever they have to continue to fly the airplane. 1141 00:43:55,925 --> 00:43:58,427 whatever they have to continue to fly the airplane.