1 00:00:02,802 --> 00:00:05,305 JIM: What is going on out there? 2 00:00:05,372 --> 00:00:07,273 FLIGHT ATTENDANT: Everyone, we're about to evacuate the plane. 3 00:00:07,340 --> 00:00:08,708 Remain calm. 4 00:00:08,775 --> 00:00:11,344 JIM: I certainly knew that with both engines on fire 5 00:00:11,411 --> 00:00:12,812 it was not going to go well. 6 00:00:12,879 --> 00:00:17,484 NARRATOR: 157 passengers rush to escape a burning 737. 7 00:00:17,550 --> 00:00:18,818 JIM: Let's go, let's go! 8 00:00:20,387 --> 00:00:22,822 KIT: It goes up like a bomb. 9 00:00:22,889 --> 00:00:25,392 ♪ 10 00:00:25,458 --> 00:00:27,861 NARRATOR: In the struggle to explain the inferno, 11 00:00:27,927 --> 00:00:31,197 the smallest parts come under intense scrutiny. 12 00:00:31,264 --> 00:00:34,033 The analysis leads to a stunning discovery. 13 00:00:34,100 --> 00:00:35,168 INVESTIGATOR: Where is it? 14 00:00:35,235 --> 00:00:37,771 BOB: It was a true breakthrough in the investigation. 15 00:00:37,837 --> 00:00:41,174 NARRATOR: The failure that doomed China Airlines Flight 120 16 00:00:41,241 --> 00:00:44,444 is putting more lives in danger every day. 17 00:00:44,511 --> 00:00:47,013 KIT: We really didn't anticipate that there's a risk, 18 00:00:47,080 --> 00:00:48,581 and it bit us. 19 00:00:49,048 --> 00:00:51,084 Flight attendant: LADIES AND GENTLEMEN, WE ARE STARTING OUR APPROACH. 20 00:00:51,151 --> 00:00:52,352 Pilot: WE LOST BOTH ENGINES! 21 00:00:52,419 --> 00:00:53,620 Flight attendant: PUT THE MASK OVER YOUR NOSE. 22 00:00:53,686 --> 00:00:54,554 EMERGENCY DESCENT. 23 00:00:54,621 --> 00:00:55,622 Pilot: MAYDAY, MAYDAY. 24 00:00:55,688 --> 00:00:57,323 Flight attendant: BRACE FOR IMPACT! 25 00:00:57,390 --> 00:00:58,625 Controller: I THINK I LOST ONE. 26 00:00:58,691 --> 00:01:01,761 Man: INVESTIGATION STARTING INTO THIS TRAGEDY... 27 00:01:01,828 --> 00:01:03,329 Man: HE'S GONNA CRASH! 28 00:01:06,166 --> 00:01:17,610 ♪ 29 00:01:17,677 --> 00:01:19,245 NARRATOR: China Airlines Flight 120 30 00:01:19,312 --> 00:01:23,917 is on final approach for landing. 31 00:01:23,983 --> 00:01:25,718 CPT. YU: Ladies and gentlemen, 32 00:01:25,785 --> 00:01:29,889 we're about to begin our descent into Okinawa Naha Airport. 33 00:01:29,956 --> 00:01:31,991 Please give the flight attendants your full cooperation 34 00:01:32,058 --> 00:01:35,395 as they prepare the cabin for landing. 35 00:01:35,462 --> 00:01:39,766 NARRATOR: The Captain is 47-year-old Yu Chien-kou. 36 00:01:39,833 --> 00:01:41,668 CPT. YU: What's the weather for approach? 37 00:01:41,734 --> 00:01:44,771 FO. TSENG: The ceiling is 8,000 feet. Winds at eight knots. 38 00:01:44,838 --> 00:01:49,008 NARRATOR: The first officer is 26-year-old Tseng Ta-wei. 39 00:01:49,075 --> 00:01:52,412 The pilots have more than 8,500 hours of flight experience 40 00:01:52,479 --> 00:01:53,413 between them. 41 00:01:53,480 --> 00:01:54,714 CPT. YU: Almost straight down the pipe. 42 00:01:54,781 --> 00:01:56,015 FO. TSENG: Yes, sir. 43 00:01:56,082 --> 00:02:00,186 NARRATOR: Landing this Boeing 737 should be routine. 44 00:02:00,253 --> 00:02:02,522 KIT: The 737 is probably the most popular airframe 45 00:02:02,589 --> 00:02:03,756 in the world. 46 00:02:03,823 --> 00:02:06,659 It's flown by most pilots as they start out in their careers. 47 00:02:06,726 --> 00:02:10,964 It's a short-range domestic airplane. 48 00:02:11,030 --> 00:02:13,700 NARRATOR: Flight 120 is a one-hour journey from Taiwan 49 00:02:13,766 --> 00:02:20,139 to the southern Japanese island of Okinawa. 50 00:02:20,206 --> 00:02:22,675 This morning, there are 157 passengers 51 00:02:22,742 --> 00:02:24,777 and eight crew on board. 52 00:02:24,844 --> 00:02:28,548 FLIGHT ATTENDANT: Please put your tray up and fasten your seat belt. 53 00:02:28,615 --> 00:02:31,451 NARRATOR: Jim Caruso is a medical examiner for the U.S. Navy 54 00:02:31,518 --> 00:02:35,021 stationed in Okinawa. 55 00:02:35,088 --> 00:02:37,790 He and his family are on the last leg of a long trip home 56 00:02:37,857 --> 00:02:39,559 from vacation. 57 00:02:39,626 --> 00:02:42,529 JIM: The family was returning from Brisbane, Australia. 58 00:02:42,595 --> 00:02:46,232 We had done probably 12 or 14 days on vacation, 59 00:02:46,299 --> 00:02:48,902 and we were hoping to be home for lunch. 60 00:02:48,968 --> 00:02:51,571 NARRATOR: Living in Okinawa has given the Carusos the chance 61 00:02:51,638 --> 00:02:54,574 to travel through much of Asia. 62 00:02:54,641 --> 00:02:58,978 JIM: We got to see China, Hong Kong, mainland Japan, Korea. 63 00:02:59,045 --> 00:03:06,219 We had made use of our location to experience the area. 64 00:03:06,286 --> 00:03:08,955 NARRATOR: Naha Airport sits at the southern end of Okinawa, 65 00:03:09,022 --> 00:03:14,027 on the shore of the East China Sea. 66 00:03:14,093 --> 00:03:16,529 The pilots reconfigure their plane as they slow down 67 00:03:16,596 --> 00:03:18,831 and descend for landing. 68 00:03:18,898 --> 00:03:21,768 CPT. YU: Let's go to flaps 25. 69 00:03:21,834 --> 00:03:23,736 FO. TSENG: Flaps 25. 70 00:03:23,803 --> 00:03:25,972 NARRATOR: They deploy flaps from the wing's back edge, 71 00:03:26,039 --> 00:03:29,976 along with slats from the front edge. 72 00:03:30,043 --> 00:03:34,047 These devices keep the plane airborne at lower speeds. 73 00:03:34,113 --> 00:03:35,315 KIT: When we start configuring, 74 00:03:35,381 --> 00:03:37,050 we begin to put out flaps and slats, 75 00:03:37,116 --> 00:03:40,286 which extend the area of the wing and give us more lift 76 00:03:40,353 --> 00:03:43,156 and allow us to fly slower. 77 00:03:43,222 --> 00:03:45,491 And of course the landing and touchdown itself 78 00:03:45,558 --> 00:03:49,262 are the most complicated part of the flight. 79 00:03:49,329 --> 00:03:53,900 NARRATOR: They're now less than a minute from the runway. 80 00:03:53,967 --> 00:03:57,203 JIM: Okay, honey. You have to remain in your seat. 81 00:03:57,270 --> 00:03:59,806 JIM: I think everybody was looking forward to landing, 82 00:03:59,872 --> 00:04:03,876 getting off the airplane and getting back to regular life. 83 00:04:10,683 --> 00:04:13,186 AUTOMATION: 30, 20, 10. 84 00:04:16,990 --> 00:04:19,492 NARRATOR: It's a textbook landing. 85 00:04:26,099 --> 00:04:27,100 CPT. YU: Flaps up. 86 00:04:33,439 --> 00:04:36,576 JIM: Once you're landed you figure you're home free. 87 00:04:36,643 --> 00:04:41,080 The taxi is usually routine. 88 00:04:41,147 --> 00:04:44,217 CPT. YU: After landing checklist. 89 00:04:44,283 --> 00:04:49,956 FO. TSENG: Speed brakes. 90 00:04:50,023 --> 00:04:52,291 NARRATOR: All that's left for the China Airlines pilots 91 00:04:52,358 --> 00:04:54,327 is to park the plane. 92 00:04:54,394 --> 00:04:55,895 FO. TSENG: Engine start levers. 93 00:04:55,962 --> 00:04:58,831 CPT. YU: Engine start levers cut off. 94 00:04:58,898 --> 00:05:02,835 NARRATOR: With the engines off they can finally relax. 95 00:05:02,902 --> 00:05:06,372 KIT: The pilot is relieved. He's no longer at risk. 96 00:05:06,439 --> 00:05:08,474 A catastrophic event after you're parked 97 00:05:08,541 --> 00:05:13,446 is almost non-existent. 98 00:05:13,513 --> 00:05:18,518 FO. TSENG: Seat belts. CPT. YU: Seat belts off. 99 00:05:18,584 --> 00:05:20,353 JIM: The biggest challenge ahead of you from there 100 00:05:20,420 --> 00:05:23,289 is making sure you can get through customs. 101 00:05:23,356 --> 00:05:25,758 No one ever expects anything to go wrong, 102 00:05:25,825 --> 00:05:28,628 especially once the engines are turned off. 103 00:05:28,695 --> 00:05:30,096 NARRATOR: But one passenger has noticed 104 00:05:30,163 --> 00:05:33,499 that something's not right. 105 00:05:33,566 --> 00:05:36,269 JIM: My wife was next to a woman 106 00:05:36,335 --> 00:05:37,937 who made some sort of exclamation 107 00:05:38,004 --> 00:05:40,740 towards the engine on the right side. 108 00:05:40,807 --> 00:05:48,448 FEMALE PASSENGER: 109 00:05:48,514 --> 00:05:50,249 JIM: What's going on? 110 00:05:50,316 --> 00:05:52,752 JIM: There was some smoke coming from that engine. 111 00:05:52,819 --> 00:05:55,054 That was the first sign that something 112 00:05:55,121 --> 00:05:56,656 was out of the ordinary. 113 00:05:56,723 --> 00:05:59,425 JIM: What is going on out there? 114 00:05:59,492 --> 00:06:02,862 FO. TSENG: Anti-ice, off. Start switches, off. 115 00:06:02,929 --> 00:06:06,199 NARRATOR: The pilots are finishing the shut-down checklist. 116 00:06:06,265 --> 00:06:07,834 FO. TSENG: Transponder T-CAS. 117 00:06:07,900 --> 00:06:13,072 CPT. YU: Hey! What is this? 118 00:06:13,139 --> 00:06:14,273 FO. TSENG: What's happening? 119 00:06:14,340 --> 00:06:16,876 NARRATOR: Just when they thought they were safely parked... 120 00:06:16,943 --> 00:06:20,213 GROUND CREW: Cockpit, ground. Number 2 engine fire. 121 00:06:20,279 --> 00:06:23,649 NARRATOR: ...a radio call alerts them to an urgent danger. 122 00:06:23,716 --> 00:06:26,252 Their plane is on fire. 123 00:06:26,319 --> 00:06:27,587 FO. TSENG: Attention, crew on station. 124 00:06:27,653 --> 00:06:29,322 Attention, crew on station. 125 00:06:29,388 --> 00:06:31,390 KIT: Bringing the flight attendants to their station 126 00:06:31,457 --> 00:06:33,559 tells them that what might likely be next 127 00:06:33,626 --> 00:06:36,696 would be an emergency evacuation. 128 00:06:36,763 --> 00:06:38,765 RADIO CALL: Dynasty 1-2-0, we are calling a fire truck. 129 00:06:38,831 --> 00:06:41,267 Remain on standby. 130 00:06:41,334 --> 00:06:45,438 FO. TSENG: We have a wheel fire. Please. 131 00:06:45,505 --> 00:06:47,507 FEMALE PASSENGER: 132 00:06:47,573 --> 00:06:50,042 FO. TSENG: Cabin crew, prepare for evacuation. 133 00:06:50,109 --> 00:06:51,744 Prepare for evacuation. 134 00:06:51,811 --> 00:06:55,047 ♪ 135 00:06:55,114 --> 00:06:56,282 FLIGHT ATTENDANT: Everyone, remain calm. 136 00:06:56,349 --> 00:07:00,787 We're about to evacuate the plane. Remain calm. 137 00:07:00,853 --> 00:07:04,524 NARRATOR: Fear begins to spread throughout the cabin. 138 00:07:04,590 --> 00:07:07,560 Outside, the fire is getting worse. 139 00:07:07,627 --> 00:07:12,165 JIM: The engine on my side also started smoking and flaming. 140 00:07:12,231 --> 00:07:15,168 So now we had both wings on fire. 141 00:07:15,234 --> 00:07:18,538 And at that point people began to panic. 142 00:07:18,604 --> 00:07:21,107 FLIGHT ATTENDANT: Remain calm! No pushing! 143 00:07:24,877 --> 00:07:27,413 JIM: I had no idea at that point how things would play out, 144 00:07:27,480 --> 00:07:30,383 but I certainly knew that with both engines on fire 145 00:07:30,449 --> 00:07:34,253 it was not going to go well. 146 00:07:36,289 --> 00:07:39,025 FO. TSENG: Parking brakes. Speed brakes. It's that lever. 147 00:07:39,091 --> 00:07:40,893 NARRATOR: The pilots know they need to get their passengers 148 00:07:40,960 --> 00:07:46,599 off the plane before flames reach the fuel tanks. 149 00:07:46,666 --> 00:07:49,969 But they can't open the cabin doors yet. 150 00:07:50,036 --> 00:07:52,572 CPT. YU: Engine fire warning switches. Override. 151 00:07:52,638 --> 00:07:55,808 NARRATOR: They must follow an evacuation checklist. 152 00:07:55,875 --> 00:07:58,711 KIT: We want the pilots to grab the list, simply read it 153 00:07:58,778 --> 00:07:59,712 and do it. 154 00:07:59,779 --> 00:08:01,781 No wondering what step is next, 155 00:08:01,848 --> 00:08:04,951 because the sequence of the steps are very important. 156 00:08:05,017 --> 00:08:09,388 CPT. YU: Pull and rotate. 157 00:08:09,455 --> 00:08:10,590 FLIGHT ATTENDANT: Everybody remain calm. 158 00:08:10,656 --> 00:08:15,494 Do not bring your luggage or personal belongings. 159 00:08:15,561 --> 00:08:21,200 NARRATOR: Seconds feel like hours as the crisis escalates. 160 00:08:21,267 --> 00:08:24,604 Finally, the pilots are ready to open the doors. 161 00:08:24,670 --> 00:08:26,806 FO. TSENG: Evacuation required now. Required. 162 00:08:26,873 --> 00:08:30,743 ♪ 163 00:08:30,810 --> 00:08:32,211 FLIGHT ATTENDANT: No pushing. No pushing. 164 00:08:32,278 --> 00:08:33,880 Please keep moving forward. 165 00:08:33,946 --> 00:08:37,316 NARRATOR: But it will take time for all 157 passengers 166 00:08:37,383 --> 00:08:40,519 to make it to the exit. 167 00:08:40,586 --> 00:08:43,723 George Ishizaki is watching the unfolding disaster 168 00:08:43,789 --> 00:08:46,926 from inside the airport terminal. 169 00:08:46,993 --> 00:08:51,063 GEORGE: I just happened to have my camcorder with me. 170 00:08:51,130 --> 00:08:54,133 I thought, oh my god, what is happening? 171 00:09:03,676 --> 00:09:05,044 FLIGHT ATTENDANT: Keep moving forward. 172 00:09:05,111 --> 00:09:07,046 NARRATOR: With the fire growing more intense, 173 00:09:07,113 --> 00:09:08,948 time is running out. 174 00:09:09,015 --> 00:09:10,583 JIM: Let's go. Let's go! 175 00:09:10,650 --> 00:09:13,653 JIM: We were quite a ways back from any exit 176 00:09:13,719 --> 00:09:16,122 since the over-wing exits were useless. 177 00:09:16,188 --> 00:09:19,392 So my focus was really to get the kids moving forward 178 00:09:19,458 --> 00:09:21,394 and off the aircraft. 179 00:09:21,460 --> 00:09:27,633 FEMALE PASSENGER (In distress): 180 00:09:27,700 --> 00:09:29,435 JIM: Go ahead. Go ahead, all right? 181 00:09:29,502 --> 00:09:32,271 NARRATOR: Jim Caruso stays behind to help other passengers 182 00:09:32,338 --> 00:09:34,740 get off the burning plane. 183 00:09:34,807 --> 00:09:36,976 JIM: I don't actually remember hesitating. 184 00:09:37,043 --> 00:09:40,079 It may have been a little difficult to make that decision 185 00:09:40,146 --> 00:09:42,815 since the kids were already moving forward. 186 00:09:42,882 --> 00:09:46,385 FLIGHT ATTENDANT: Hey, no pushing. Keep moving forward. 187 00:09:52,658 --> 00:09:55,861 GEORGE: The smoke actually started building, and 188 00:09:55,928 --> 00:09:58,931 that's when everything started happening really quickly. 189 00:10:03,769 --> 00:10:07,239 ♪ 190 00:10:07,306 --> 00:10:10,076 NARRATOR: Jim Caruso is separated from his family. 191 00:10:10,142 --> 00:10:14,914 The heat and smoke are getting worse. He hears a cry for help. 192 00:10:14,981 --> 00:10:16,582 FEMALE PASSENGER: 193 00:10:16,649 --> 00:10:20,353 JIM: The woman behind me pointed towards the overhead bin. 194 00:10:20,419 --> 00:10:22,588 I was concerned if she was pointing towards 195 00:10:22,655 --> 00:10:24,256 flames coming in. 196 00:10:24,323 --> 00:10:25,358 FEMALE PASSENGER: 197 00:10:25,424 --> 00:10:28,227 JIM: I looked up and I saw a pair of crutches. 198 00:10:36,836 --> 00:10:39,171 GEORGE: Everybody was just sliding down the slides, 199 00:10:39,238 --> 00:10:42,742 and once they got on the ground they were just scrambling. 200 00:10:44,243 --> 00:10:45,911 ♪ 201 00:10:45,978 --> 00:10:48,180 JIM: Once the smoke and fire started building, 202 00:10:48,247 --> 00:10:51,017 the cabin became rather warm. 203 00:10:51,083 --> 00:10:52,918 I do recall some of the windows actually cracking 204 00:10:52,985 --> 00:10:56,789 from the heat. 205 00:10:56,856 --> 00:10:59,859 NARRATOR: Finally, they make it to the exit. 206 00:11:06,132 --> 00:11:09,668 ♪ 207 00:11:09,735 --> 00:11:12,505 The plane has been burning for close to three minutes. 208 00:11:12,571 --> 00:11:15,007 It could explode at any moment. 209 00:11:15,074 --> 00:11:17,243 FLIGHT ATTENDANT: 210 00:11:17,309 --> 00:11:19,245 Captain, all passengers are evacuated. 211 00:11:19,311 --> 00:11:20,813 You're the last ones. 212 00:11:24,517 --> 00:11:26,519 CPT. YU: We gotta get out of here. 213 00:11:30,689 --> 00:11:32,725 KIT: Typically, the captain will stay until everybody's off 214 00:11:32,792 --> 00:11:37,797 and he will verify that the airplane is empty. 215 00:11:37,863 --> 00:11:41,067 NARRATOR: The pilots have put their passengers' safety first. 216 00:11:41,133 --> 00:11:43,869 But now it may be too late for them. 217 00:11:43,936 --> 00:11:45,671 CPT. YU: We're going to have to climb out through the window. 218 00:11:45,738 --> 00:11:46,605 You first. 219 00:11:46,672 --> 00:11:47,740 FO. TSENG: Yes, sir. 220 00:11:47,807 --> 00:11:49,708 NARRATOR: All 737 cockpits are equipped 221 00:11:49,775 --> 00:11:52,278 with an emergency escape rope. 222 00:11:52,344 --> 00:11:55,815 It's designed to help pilots exit through the side window, 223 00:11:55,881 --> 00:11:58,017 but it's no easy maneuver. 224 00:11:58,084 --> 00:12:00,786 KIT: Exiting the airplane is more difficult than it sounds. 225 00:12:00,853 --> 00:12:05,891 It's a relatively small window. Going down the rope has a risk. 226 00:12:05,958 --> 00:12:09,829 ♪ 227 00:12:09,895 --> 00:12:12,298 Then... 228 00:12:13,632 --> 00:12:19,572 WITNESS: Oh. Whoa. Whoa. Oh my god! 229 00:12:19,638 --> 00:12:24,343 GEORGE: You felt a huge kaboom. 230 00:12:24,410 --> 00:12:28,180 I've never felt anything like that. 231 00:12:28,247 --> 00:12:31,016 JIM: We actually could feel the ground shake. 232 00:12:31,083 --> 00:12:34,653 ♪ 233 00:12:34,720 --> 00:12:37,356 NARRATOR: Passengers run to safety as a fiery explosion 234 00:12:37,423 --> 00:12:41,694 engulfs the plane they just escaped. 235 00:12:41,760 --> 00:12:45,197 The fate of the pilots is still unknown. 236 00:12:45,264 --> 00:12:47,500 JIM: As I looked back after the first explosion, 237 00:12:47,566 --> 00:12:50,669 I recall crew members fast-roping, as it were, 238 00:12:50,736 --> 00:12:53,672 out of the cockpit. 239 00:12:53,739 --> 00:12:57,443 NARRATOR: The force of the blast overpowers the first officer. 240 00:12:57,510 --> 00:13:00,980 GEORGE: He dropped down from the height of the cockpit window 241 00:13:01,046 --> 00:13:02,615 onto the ground. 242 00:13:02,681 --> 00:13:04,650 NARRATOR: Incredibly, he's able to get up and run away 243 00:13:04,717 --> 00:13:11,056 from the flames. The captain quickly follows. 244 00:13:11,123 --> 00:13:12,625 GEORGE: It was good that he did that, 245 00:13:12,691 --> 00:13:15,728 because the fire just gutted the airplane. 246 00:13:15,794 --> 00:13:18,931 NARRATOR: More explosions rock the airplane. 247 00:13:18,998 --> 00:13:20,599 GEORGE: The fuselage I guess melted. 248 00:13:20,666 --> 00:13:23,035 The back half just kind of fell to the ground. 249 00:13:24,336 --> 00:13:28,240 NARRATOR: Finally, fire trucks arrive on the scene. 250 00:13:28,307 --> 00:13:30,609 JIM: Everybody had exited the aircraft at that point 251 00:13:30,676 --> 00:13:33,679 and was gathering in the terminal. 252 00:13:38,050 --> 00:13:40,653 It was a huge relief to have the kids 253 00:13:40,719 --> 00:13:43,222 and my wife and I together. 254 00:13:43,289 --> 00:13:45,524 We certainly were looking back at the aircraft again 255 00:13:45,591 --> 00:13:50,029 in amazement. 256 00:13:50,095 --> 00:13:53,632 NARRATOR: Fire on an airplane can quickly become lethal. 257 00:13:53,699 --> 00:13:58,003 Incredibly, on Flight 120, all 165 people on board 258 00:13:58,070 --> 00:14:00,906 have escaped unharmed. 259 00:14:00,973 --> 00:14:02,841 KIT: I've never heard of any evacuation 260 00:14:02,908 --> 00:14:05,044 where somebody wasn't hurt. 261 00:14:05,110 --> 00:14:07,880 To get this many people off in such a dire circumstance 262 00:14:07,947 --> 00:14:12,218 in a very short period of time with no injuries is miraculous. 263 00:14:12,284 --> 00:14:14,587 ♪ 264 00:14:14,653 --> 00:14:15,988 NARRATOR: If there's a next time, 265 00:14:16,055 --> 00:14:19,191 passengers may not be so lucky. 266 00:14:19,258 --> 00:14:21,160 Pressure to figure out what happened falls 267 00:14:21,227 --> 00:14:25,698 on an international team of air crash investigators. 268 00:14:25,764 --> 00:14:30,869 THOMAS: Okay. Let's get to work. 269 00:14:30,936 --> 00:14:32,905 NARRATOR: They need to explain how an airliner 270 00:14:32,972 --> 00:14:36,175 that had landed safely and turned off its engines 271 00:14:36,242 --> 00:14:38,244 suddenly burst into flames. 272 00:14:40,646 --> 00:14:44,550 THOMAS: We have no clue. We do not know what happened. 273 00:14:44,617 --> 00:14:47,853 We tried to find out from the wreckage that remained 274 00:14:47,920 --> 00:14:51,090 still on the apron. 275 00:14:51,156 --> 00:14:53,359 BOB: Normally fires occur in-flight, 276 00:14:53,425 --> 00:14:55,494 perhaps during taxi sometimes, 277 00:14:55,561 --> 00:14:59,898 but rarely in a parking spot after the engines are shut down. 278 00:14:59,965 --> 00:15:03,002 THOMAS: The challenge for the investigator is, 279 00:15:03,068 --> 00:15:06,071 most of the evidence will be destroyed by the fire. 280 00:15:10,776 --> 00:15:13,112 NARRATOR: Across the globe, there are more than 5,000 281 00:15:13,178 --> 00:15:17,449 Boeing 737s in service. 282 00:15:17,516 --> 00:15:19,785 KIT: There's a 737 taking off and landing 283 00:15:19,852 --> 00:15:23,489 every three or four seconds in the world. 284 00:15:23,555 --> 00:15:25,357 NARRATOR: If the plane has a design flaw 285 00:15:25,424 --> 00:15:28,861 that somehow leads to uncontainable fire, 286 00:15:28,927 --> 00:15:32,298 countless passengers could be at risk. 287 00:15:32,364 --> 00:15:33,799 BOB: We were aware that the 737 288 00:15:33,866 --> 00:15:36,435 is probably the most popular airliner out there. 289 00:15:36,502 --> 00:15:38,837 So there's a reason once an accident occurs 290 00:15:38,904 --> 00:15:42,408 to try to figure out what happened pretty darn quickly. 291 00:15:46,779 --> 00:15:48,080 ♪ 292 00:15:48,147 --> 00:15:50,382 NARRATOR: The search for Flight 120's black boxes 293 00:15:50,449 --> 00:15:52,818 begins immediately. 294 00:15:52,885 --> 00:15:54,219 BOB: One of our main goals initially 295 00:15:54,286 --> 00:15:56,288 is to try to find the cockpit voice recorder 296 00:15:56,355 --> 00:15:58,223 and the flight data recorder. 297 00:15:58,290 --> 00:16:00,726 These are important, because a lot of times 298 00:16:00,793 --> 00:16:03,295 they tell us what happened. 299 00:16:03,362 --> 00:16:04,596 NARRATOR: But investigators know that 300 00:16:04,663 --> 00:16:06,465 after such an intense fire 301 00:16:06,532 --> 00:16:11,403 there's a chance the black box data will be lost. 302 00:16:11,470 --> 00:16:13,739 They need other leads. 303 00:16:13,806 --> 00:16:15,441 BOB: Good investigators don't rely totally 304 00:16:15,507 --> 00:16:17,476 on flight data recorders, for instance, 305 00:16:17,543 --> 00:16:20,379 or cockpit voice recorders because they can be destroyed. 306 00:16:20,446 --> 00:16:23,682 So we rely on witnesses to tell us their impression 307 00:16:23,749 --> 00:16:26,285 of what happened. 308 00:16:26,352 --> 00:16:27,886 CPT. YU: Well, we taxied off the runway 309 00:16:27,953 --> 00:16:30,689 down the apron to our assigned parking spot. 310 00:16:30,756 --> 00:16:32,691 FO. TSENG: Once we parked, we shut off the engines, 311 00:16:32,758 --> 00:16:36,495 and some time after that we heard the aircraft was on fire. 312 00:16:36,562 --> 00:16:39,098 BOB: We needed to know what type of fire it was, 313 00:16:39,164 --> 00:16:41,433 what the ignition source would be, 314 00:16:41,500 --> 00:16:43,602 what the fuel source would be. 315 00:16:43,669 --> 00:16:47,773 Those were the areas of our main questioning right off the bat. 316 00:16:47,840 --> 00:16:49,575 FO. TSENG: I radioed the controller letting him know 317 00:16:49,641 --> 00:16:51,143 we had a wheel fire. 318 00:16:55,214 --> 00:16:57,649 NARRATOR: Investigators know that if a wheel caught fire 319 00:16:57,716 --> 00:17:02,154 on Flight 120, there's more than one possible cause. 320 00:17:02,221 --> 00:17:05,691 A deflated tire can result in burning rubber. 321 00:17:05,758 --> 00:17:07,593 Overheated brake pads could potentially 322 00:17:07,659 --> 00:17:10,095 ignite hydraulic fluid. 323 00:17:10,162 --> 00:17:11,296 BOB: In a wheel well of an aircraft 324 00:17:11,363 --> 00:17:13,532 there are a lot of hydraulic lines 325 00:17:13,599 --> 00:17:17,302 going to the landing gear assemblies and things like that. 326 00:17:17,369 --> 00:17:19,405 Hydraulic fluid is very flammable. 327 00:17:19,471 --> 00:17:22,341 If a hydraulic leak occurred and it happened to drip 328 00:17:22,408 --> 00:17:26,412 onto a hot brake for instance, well, there you go. 329 00:17:27,713 --> 00:17:29,915 CPT. YU: Hey. What is this? FO. TSENG: We have a wheel fire. 330 00:17:29,982 --> 00:17:32,885 NARRATOR: If the pilots are right about where the fire started, 331 00:17:32,951 --> 00:17:39,658 investigators should be able to find proof. 332 00:17:39,725 --> 00:17:42,094 They examine the plane's right side wheel well 333 00:17:42,161 --> 00:17:44,897 and landing gear assembly. 334 00:17:44,963 --> 00:17:48,233 They find scorched wreckage, but not enough to convince them 335 00:17:48,300 --> 00:17:51,003 that this is where the fire began. 336 00:17:51,069 --> 00:17:52,538 BOB: Once we were able to closely examine 337 00:17:52,604 --> 00:17:54,206 that part of the aircraft, 338 00:17:54,273 --> 00:17:56,842 we were very confident that a wheel well fire per se 339 00:17:56,909 --> 00:17:58,277 did not occur. 340 00:17:58,343 --> 00:18:00,479 The seat of the fire seemed to be forward 341 00:18:00,546 --> 00:18:03,115 and a little bit to the right of the wheel well area. 342 00:18:03,182 --> 00:18:04,883 NARRATOR: It seems the pilots were mistaken 343 00:18:04,950 --> 00:18:07,853 about the origins of the fire. 344 00:18:07,920 --> 00:18:10,222 Where it started remains a mystery. 345 00:18:10,289 --> 00:18:14,293 ♪ 346 00:18:14,359 --> 00:18:17,663 Solving that mystery may have just become easier. 347 00:18:17,729 --> 00:18:22,534 Investigators have recovered the plane's black boxes. 348 00:18:22,601 --> 00:18:27,606 THOMAS: The Japanese team retrieved both the Boeing's CVR and FDR. 349 00:18:27,673 --> 00:18:31,243 THOMAS: Let's get working on the FDR immediately. 350 00:18:31,310 --> 00:18:34,079 BOB: On modern 737s, the flight data recorder 351 00:18:34,146 --> 00:18:37,015 has thousands of parameters, 352 00:18:37,082 --> 00:18:43,322 data bits that come in to the recording device itself. 353 00:18:43,388 --> 00:18:46,492 It will take time to download and verify all the data. 354 00:18:46,558 --> 00:18:51,029 ♪ 355 00:18:51,096 --> 00:18:53,165 NARRATOR: Meanwhile, the charred fire scene 356 00:18:53,232 --> 00:18:57,936 continues to challenge investigators. 357 00:18:58,003 --> 00:19:00,973 THOMAS: With all this heat damage it's nearly impossible 358 00:19:01,039 --> 00:19:03,408 to tell where the fire started. 359 00:19:03,475 --> 00:19:04,877 NARRATOR: They're almost certain the fire began 360 00:19:04,943 --> 00:19:08,881 on the right side of the plane as witnesses reported. 361 00:19:08,947 --> 00:19:11,116 But where exactly? 362 00:19:11,183 --> 00:19:14,052 THOMAS: Wait a sec. 363 00:19:14,119 --> 00:19:17,523 NARRATOR: Scorched wires provide a promising new lead. 364 00:19:17,589 --> 00:19:18,790 THOMAS: What do you think? 365 00:19:18,857 --> 00:19:22,461 NARRATOR: Did an electrical fire destroy Flight 120? 366 00:19:22,528 --> 00:19:28,667 Serious electrical failures are rare, but not unheard of. 367 00:19:28,734 --> 00:19:31,970 In 1998, the cockpit of Swissair Flight 111 368 00:19:32,037 --> 00:19:35,240 began filling with smoke shortly after takeoff. 369 00:19:35,307 --> 00:19:37,276 The pilots tried to make an emergency landing 370 00:19:37,342 --> 00:19:41,013 in Halifax, Canada. They never made it. 371 00:19:41,079 --> 00:19:43,582 Their plane disappeared into the Atlantic Ocean, 372 00:19:43,649 --> 00:19:47,419 killing all 229 people onboard. 373 00:19:47,486 --> 00:19:49,688 Investigators found that an electrical fault 374 00:19:49,755 --> 00:19:51,490 in the entertainment system 375 00:19:51,557 --> 00:19:55,294 almost certainly sparked the fire that doomed the plane. 376 00:19:59,565 --> 00:20:03,235 THOMAS: Okay. Let's see what we got. 377 00:20:03,302 --> 00:20:05,337 NARRATOR: If the fire aboard Flight 120 378 00:20:05,404 --> 00:20:07,272 was caused by faulty wiring, 379 00:20:07,339 --> 00:20:10,375 investigators may now be able to confirm it. 380 00:20:10,442 --> 00:20:13,979 They've successfully downloaded the black box data. 381 00:20:14,046 --> 00:20:17,416 Any electrical problem or failure in any onboard system 382 00:20:17,482 --> 00:20:20,118 should show up in the data. 383 00:20:20,185 --> 00:20:22,821 BOB: Almost every system on the aircraft is recorded. 384 00:20:22,888 --> 00:20:24,990 Its status is recorded. 385 00:20:25,057 --> 00:20:26,258 So we looked very quickly through 386 00:20:26,325 --> 00:20:30,329 these hundreds of electrical possibilities 387 00:20:30,395 --> 00:20:32,264 and we found nothing. 388 00:20:32,331 --> 00:20:35,000 THOMAS: It wasn't electrical. 389 00:20:35,067 --> 00:20:37,569 NARRATOR: The analysis comes up empty. 390 00:20:37,636 --> 00:20:40,172 THOMAS: At that time we can rule out some wheel fire 391 00:20:40,238 --> 00:20:42,741 or some other electrical fire. 392 00:20:49,214 --> 00:20:50,649 NARRATOR: Investigators turn their attention 393 00:20:50,716 --> 00:20:55,087 to the aircraft's right engine. 394 00:20:55,153 --> 00:20:58,023 In flight, the CFM-56 power plant 395 00:20:58,090 --> 00:20:59,725 generates internal temperatures of more 396 00:20:59,791 --> 00:21:06,598 than 2,000 degrees Fahrenheit, hotter than molten lava. 397 00:21:06,665 --> 00:21:10,502 Could an engine fire have sparked the inferno? 398 00:21:10,569 --> 00:21:14,272 BOB: We of course looked at the engines very carefully, 399 00:21:14,339 --> 00:21:15,474 the right engine especially 400 00:21:15,540 --> 00:21:18,043 because there was a lot of fire damage around it. 401 00:21:18,110 --> 00:21:20,278 It was fairly easy to look inside the engine 402 00:21:20,345 --> 00:21:22,814 and examine the core, so to speak, 403 00:21:22,881 --> 00:21:26,551 where all the damage in an engine failure usually occurs. 404 00:21:26,618 --> 00:21:29,121 And we found nothing wrong. 405 00:21:34,226 --> 00:21:36,628 The engine was damaged externally but not internally, 406 00:21:36,695 --> 00:21:43,201 so we eliminated it as a possible factor. 407 00:21:43,268 --> 00:21:47,506 THOMAS: What could have burned this entire plane down? 408 00:21:47,572 --> 00:21:50,042 NARRATOR: The investigation has hit a wall. 409 00:21:50,108 --> 00:21:53,311 The cause of the catastrophic fire remains unknown, 410 00:21:53,378 --> 00:21:59,117 while every day thousands of 737s continue to fly. 411 00:21:59,184 --> 00:22:00,919 There's growing pressure on investigators 412 00:22:00,986 --> 00:22:02,854 to find the answer. 413 00:22:02,921 --> 00:22:05,490 BOB: We knew we had a little bit of detective work ahead of us 414 00:22:05,557 --> 00:22:07,059 and we pressed on. 415 00:22:11,797 --> 00:22:12,597 ♪ 416 00:22:14,966 --> 00:22:17,002 NARRATOR: The video capturing the fiery destruction 417 00:22:17,069 --> 00:22:19,204 of China Airlines Flight 120 418 00:22:19,271 --> 00:22:20,806 could provide investigators with clues 419 00:22:20,872 --> 00:22:23,375 to what started the fire. 420 00:22:27,679 --> 00:22:29,548 THOMAS: Whoa. 421 00:22:29,614 --> 00:22:31,483 NARRATOR: The footage reveals just how quickly 422 00:22:31,550 --> 00:22:34,319 the flames spread through the passenger jet. 423 00:22:34,386 --> 00:22:38,390 But for investigators, the most important clue is missing. 424 00:22:38,457 --> 00:22:40,659 The recording hasn't captured the critical moment 425 00:22:40,726 --> 00:22:44,029 the fire started. 426 00:22:44,096 --> 00:22:48,233 THOMAS: From the video, we can only understand 427 00:22:48,300 --> 00:22:51,970 there was fire and the location of the fire 428 00:22:52,037 --> 00:22:56,875 and it seems that something was feeding to the fire. 429 00:22:56,942 --> 00:23:02,948 But we cannot understand why. 430 00:23:03,014 --> 00:23:05,183 ♪ 431 00:23:05,250 --> 00:23:09,654 NARRATOR: Investigators widen the search for leads. 432 00:23:09,721 --> 00:23:11,389 THOMAS: What did you see? 433 00:23:11,456 --> 00:23:13,992 NARRATOR: The effort pays off when an airport ground worker 434 00:23:14,059 --> 00:23:17,229 provides a critical detail. 435 00:23:17,295 --> 00:23:19,498 BOB: A ramp worker on the right side of the aircraft 436 00:23:19,564 --> 00:23:23,001 said very distinctly that he saw a liquid 437 00:23:23,068 --> 00:23:25,437 running down the leading edge of the right wing 438 00:23:25,504 --> 00:23:28,173 before the fire broke out. 439 00:23:28,240 --> 00:23:31,143 THOMAS: Thanks. 440 00:23:31,209 --> 00:23:33,044 NARRATOR: Fluid leaking from this part of the wing 441 00:23:33,111 --> 00:23:37,616 of the aircraft can be only one thing: jet fuel. 442 00:23:42,621 --> 00:23:47,359 The 737 holds 4,390 gallons of fuel, 443 00:23:47,425 --> 00:23:48,827 much of it in tanks located 444 00:23:48,894 --> 00:23:52,597 inside the plane's two massive wings. 445 00:23:52,664 --> 00:23:56,234 BOB: When we figured out that an actual fuel leak had occurred, 446 00:23:56,301 --> 00:23:57,569 it was a breakthrough, 447 00:23:57,636 --> 00:24:01,606 a true breakthrough in the investigation. 448 00:24:01,673 --> 00:24:07,979 We now needed to know why it originated. 449 00:24:08,046 --> 00:24:12,384 THOMAS: We know the fuel was leaking, but from where? 450 00:24:12,450 --> 00:24:15,053 A fuel line? 451 00:24:15,120 --> 00:24:17,556 NARRATOR: Finding solid evidence amongst the burnt remains 452 00:24:17,622 --> 00:24:20,625 of the plane's fuel system won't be easy. 453 00:24:24,629 --> 00:24:27,799 The Boeing 737-800 has high-pressure pumps 454 00:24:27,866 --> 00:24:29,835 inside the wing. 455 00:24:29,901 --> 00:24:34,472 They deliver 200 gallons of fuel per hour to the engine. 456 00:24:34,539 --> 00:24:37,909 All that fuel flows through flexible pipes. 457 00:24:37,976 --> 00:24:41,012 Could one of those fuel pipes be the culprit? 458 00:24:41,079 --> 00:24:42,948 BOB: Fuel lines are probably in a sense 459 00:24:43,014 --> 00:24:45,851 the most vulnerable part of a fuel system. 460 00:24:45,917 --> 00:24:48,653 They take bends and sometimes they're exposed 461 00:24:48,720 --> 00:24:51,723 where they could get knocked or punctured by something. 462 00:24:51,790 --> 00:24:55,026 So we tried to trace the entire fuel system of the aircraft. 463 00:24:55,093 --> 00:25:02,834 ♪ 464 00:25:02,901 --> 00:25:04,870 NARRATOR: It's another dead end. 465 00:25:04,936 --> 00:25:07,205 THOMAS: It wasn't the fuel lines. 466 00:25:07,272 --> 00:25:12,143 NARRATOR: None of the fuel lines are ruptured. 467 00:25:12,210 --> 00:25:13,478 BOB: We had a lot of fire damage, 468 00:25:13,545 --> 00:25:17,449 but the fuel lines that we examined seemed to be intact 469 00:25:17,515 --> 00:25:19,417 and functional. 470 00:25:19,484 --> 00:25:22,854 NARRATOR: Investigators still can't explain the fire. 471 00:25:22,921 --> 00:25:24,789 They know enough fuel leaked from the plane 472 00:25:24,856 --> 00:25:29,294 to feed the flames, but they don't know where it came from. 473 00:25:29,361 --> 00:25:31,696 BOB: Once we eliminated fuel lines per se 474 00:25:31,763 --> 00:25:35,100 as a possible problem, 475 00:25:35,166 --> 00:25:37,035 pretty much the only thing out in that area 476 00:25:37,102 --> 00:25:40,805 that could have gone wrong is a leak in the fuel tank itself. 477 00:25:40,872 --> 00:25:44,376 NARRATOR: The plane's fuel tanks are made from aluminum alloy 478 00:25:44,442 --> 00:25:48,213 and designed to withstand the rigors of flight for years. 479 00:25:48,280 --> 00:25:51,182 They should never crack or leak. 480 00:25:51,249 --> 00:25:52,284 Examining them 481 00:25:52,350 --> 00:25:55,987 presents one of the most difficult challenges yet. 482 00:25:56,054 --> 00:26:00,425 They hope a tool called a borescope will do the trick. 483 00:26:00,492 --> 00:26:04,195 It's a small camera that can peer into tight spaces. 484 00:26:04,262 --> 00:26:05,497 It gives them a unique view 485 00:26:05,563 --> 00:26:08,566 inside the plane's right wing fuel tank. 486 00:26:16,508 --> 00:26:18,910 What it reveals changes the entire course 487 00:26:18,977 --> 00:26:22,948 of this investigation. 488 00:26:23,014 --> 00:26:25,016 THOMAS: Whoa. Would you look at that? 489 00:26:25,083 --> 00:26:26,785 BOB: All of a sudden, clear as a bell, 490 00:26:26,851 --> 00:26:32,624 we saw this bolt sticking out of the fuel tank itself. 491 00:26:32,691 --> 00:26:36,561 Where the bolt came from is a complete mystery, 492 00:26:36,628 --> 00:26:38,163 but it has ruptured the tank 493 00:26:38,229 --> 00:26:41,333 right where the ground worker spotted leaking fuel. 494 00:26:41,399 --> 00:26:43,768 BOB: It's hard to describe how significant this was. 495 00:26:43,835 --> 00:26:49,074 I mean, this was the core of the investigation. 496 00:26:49,140 --> 00:26:51,409 Now we knew what happened. 497 00:26:51,476 --> 00:26:53,478 The rest of the investigation was trying to figure out 498 00:26:53,545 --> 00:26:56,781 why this occurred. 499 00:26:56,848 --> 00:26:58,550 NARRATOR: A punctured fuel tank was the cause 500 00:26:58,616 --> 00:27:04,356 of one of the most infamous air crashes in history. 501 00:27:04,422 --> 00:27:08,326 A supersonic Air France Concorde burst into flames on takeoff 502 00:27:08,393 --> 00:27:13,431 after running over a piece of metal debris on the runway. 503 00:27:13,498 --> 00:27:16,134 Did a similar scenario lead to the total destruction 504 00:27:16,201 --> 00:27:20,705 of China Airlines Flight 120? 505 00:27:20,772 --> 00:27:23,908 THOMAS: Okay. We need to cut into this wing. 506 00:27:23,975 --> 00:27:25,977 NARRATOR: Investigators need to get a closer look 507 00:27:26,044 --> 00:27:30,949 at the mysterious bolt that made a hole in the fuel tank. 508 00:27:31,016 --> 00:27:33,385 BOB: The investigator in charge said, yep, 509 00:27:33,451 --> 00:27:36,454 now's the time to start cutting into that thing. 510 00:27:39,457 --> 00:27:49,434 ♪ 511 00:27:49,501 --> 00:27:56,274 ♪ 512 00:27:56,341 --> 00:27:59,377 THOMAS: Okay. Got it. 513 00:27:59,444 --> 00:28:05,917 NARRATOR: Now they need to figure out where the bolt came from. 514 00:28:05,984 --> 00:28:12,757 They study schematics of the 737 wing structure. 515 00:28:12,824 --> 00:28:14,159 BOB: We went back to the drawings 516 00:28:14,225 --> 00:28:16,795 and went back to things like maintenance records 517 00:28:16,861 --> 00:28:19,531 to try to figure out exactly what it was. 518 00:28:19,597 --> 00:28:22,100 NARRATOR: They soon get their answer. 519 00:28:31,376 --> 00:28:33,912 THOMAS: A downstop assembly. 520 00:28:33,978 --> 00:28:36,815 NARRATOR: The downstop assembly is part of the slat mechanism 521 00:28:36,881 --> 00:28:39,584 on the wing's leading edge. 522 00:28:39,651 --> 00:28:44,155 CPT. YU: Let's go to flaps 25. FO. TSENG: Flaps 25. 523 00:28:44,222 --> 00:28:46,091 NARRATOR: Pilots extend flaps and slats 524 00:28:46,157 --> 00:28:50,662 during every takeoff and landing. 525 00:28:50,728 --> 00:28:53,131 The downstop is fixed to the end of a track 526 00:28:53,198 --> 00:28:55,867 that slides back and forth. 527 00:28:55,934 --> 00:28:59,437 The device prevents the slats from moving too far forward. 528 00:28:59,504 --> 00:29:02,707 RODNEY: The downstop is there, quite frankly, to stop it 529 00:29:02,774 --> 00:29:05,543 when it reaches its maximum deployment length. 530 00:29:05,610 --> 00:29:10,014 If it didn't exist then there would be no way 531 00:29:10,081 --> 00:29:15,587 to retain the slat on the aircraft. 532 00:29:15,653 --> 00:29:17,388 NARRATOR: Investigators have identified the piece 533 00:29:17,455 --> 00:29:20,959 that penetrated the fuel tank. 534 00:29:21,025 --> 00:29:22,760 They know it's not from another plane, 535 00:29:22,827 --> 00:29:27,932 like the runway debris that caused the Concorde disaster. 536 00:29:27,999 --> 00:29:32,170 But they have other important questions that need answers. 537 00:29:32,237 --> 00:29:34,806 BOB: We had the assembly. We knew it punctured the tank. 538 00:29:34,873 --> 00:29:36,674 Our next step was trying to figure out 539 00:29:36,741 --> 00:29:39,244 how this could possibly have occurred. 540 00:29:43,581 --> 00:29:47,485 ♪ 541 00:29:47,552 --> 00:29:50,288 NARRATOR: Investigators pore over Boeing service documents 542 00:29:50,355 --> 00:29:56,961 to learn more about downstop assemblies on the 737. 543 00:29:57,028 --> 00:29:58,963 They make a surprising discovery. 544 00:29:59,030 --> 00:30:00,665 THOMAS: This has happened before, 545 00:30:00,732 --> 00:30:03,835 and it's happened more than once. 546 00:30:03,902 --> 00:30:08,306 ♪ 547 00:30:08,373 --> 00:30:10,074 BOB: There'd been two previous instances 548 00:30:10,141 --> 00:30:15,480 of this device coming apart and causing minor fuel leaks, 549 00:30:15,547 --> 00:30:19,484 but this was the first instance of an actual destructive fire. 550 00:30:19,551 --> 00:30:23,555 In both previous instances, parts from a downstop assembly 551 00:30:23,621 --> 00:30:29,761 punctured a fuel tank, just like on Flight 120. 552 00:30:29,827 --> 00:30:32,730 THOMAS: Clearly, they knew it was a problem. 553 00:30:32,797 --> 00:30:35,066 NARRATOR: Boeing was so concerned about the problem, 554 00:30:35,133 --> 00:30:36,668 it issued a special work order 555 00:30:36,734 --> 00:30:42,473 to secure the downstop assembly on all 737s worldwide. 556 00:30:42,540 --> 00:30:45,610 RODNEY: The solution that Boeing had recommended 557 00:30:45,677 --> 00:30:50,648 was to remove the nut from this particular device 558 00:30:50,715 --> 00:30:54,886 and install some thread hardening material, 559 00:30:54,953 --> 00:31:00,758 and then you reinstall the nut. It hardens in place. 560 00:31:00,825 --> 00:31:02,493 THOMAS: What if the work order on this plane 561 00:31:02,560 --> 00:31:04,195 was never completed? 562 00:31:04,262 --> 00:31:08,766 NARRATOR: Investigators review the Boeing work orders. 563 00:31:08,833 --> 00:31:12,537 If the plane that burned in Okinawa was never fixed, 564 00:31:12,604 --> 00:31:15,073 that could explain the accident. 565 00:31:15,139 --> 00:31:16,207 THOMAS: We tried to figure out 566 00:31:16,274 --> 00:31:21,846 when is the last time anybody touched that assembly. 567 00:31:21,913 --> 00:31:23,748 NARRATOR: But according to the records, 568 00:31:23,815 --> 00:31:27,418 the proper work was carried out very recently. 569 00:31:27,485 --> 00:31:29,854 BOB: We discovered that this particular component, 570 00:31:29,921 --> 00:31:32,123 this downstop, had been manipulated 571 00:31:32,190 --> 00:31:35,293 only a couple of weeks or so prior to the accident. 572 00:31:35,360 --> 00:31:37,962 THOMAS: It just doesn't make sense. 573 00:31:38,029 --> 00:31:40,064 NARRATOR: Investigators can see that the nut 574 00:31:40,131 --> 00:31:44,302 on the downstop assembly is still attached. 575 00:31:44,369 --> 00:31:47,305 It seems that the work order to replace it was completed 576 00:31:47,372 --> 00:31:52,677 just as the records show. So what went wrong? 577 00:31:52,744 --> 00:31:55,813 THOMAS: That's the weird part that we wanted to figure out 578 00:31:55,880 --> 00:31:58,349 at that time. 579 00:31:58,416 --> 00:32:02,487 NARRATOR: They examine the downstop assembly from Flight 120. 580 00:32:02,553 --> 00:32:05,189 ♪ 581 00:32:05,256 --> 00:32:09,927 They check all the component parts. 582 00:32:09,994 --> 00:32:14,299 Finally, they spot something. 583 00:32:14,365 --> 00:32:17,335 BOB: We decided to count parts, and lo and behold, 584 00:32:17,402 --> 00:32:20,505 a washer was missing. 585 00:32:20,571 --> 00:32:23,074 ♪ 586 00:32:23,141 --> 00:32:26,044 THOMAS: Where is it? 587 00:32:26,110 --> 00:32:29,514 NARRATOR: There's supposed to be a washer right behind the nut. 588 00:32:29,580 --> 00:32:31,082 Could a single missing washer 589 00:32:31,149 --> 00:32:35,253 have played a role in the accident? It seems unlikely. 590 00:32:35,320 --> 00:32:38,222 But investigators can't rule it out. 591 00:32:38,289 --> 00:32:40,358 They need to find the washer. 592 00:32:40,425 --> 00:32:41,626 BOB: We thought initially that the washer 593 00:32:41,693 --> 00:32:44,262 may have somehow gotten inside the fuel tank, 594 00:32:44,329 --> 00:32:47,665 but that's not the case at all. 595 00:32:47,732 --> 00:32:51,769 We examined very carefully the rest of the wing, 596 00:32:51,836 --> 00:32:53,604 and we found that particular washer 597 00:32:53,671 --> 00:32:56,341 in the leading edge assembly of the wing, 598 00:32:56,407 --> 00:32:58,343 just laying in there loose. 599 00:33:01,813 --> 00:33:03,781 THOMAS: The washer is a fit. 600 00:33:03,848 --> 00:33:05,249 NARRATOR: Recovering the missing washer 601 00:33:05,316 --> 00:33:08,453 raises a puzzling question. 602 00:33:08,519 --> 00:33:11,255 BOB: The nut was on there and it was torqued down correctly, 603 00:33:11,322 --> 00:33:14,826 but there was no washer on it at all. 604 00:33:14,892 --> 00:33:17,662 How did the washer become detached from the bolt 605 00:33:17,729 --> 00:33:19,297 but not the nut? 606 00:33:19,364 --> 00:33:21,599 THOMAS: If the nut is still on the bolt, 607 00:33:21,666 --> 00:33:27,238 why is there something between that fell off? 608 00:33:27,305 --> 00:33:29,173 NARRATOR: It seems like an impossibility, 609 00:33:29,240 --> 00:33:31,743 and yet somehow it happened. 610 00:33:37,281 --> 00:33:40,985 The Flight 120 fire investigation heads to Taiwan 611 00:33:41,052 --> 00:33:45,523 and the headquarters of China Airlines. 612 00:33:45,590 --> 00:33:47,492 Investigators hope to shed some light 613 00:33:47,558 --> 00:33:49,994 on the mystery of the detached washer. 614 00:33:50,061 --> 00:33:53,998 THOMAS: I appreciate you making the time. 615 00:33:54,065 --> 00:33:56,100 THOMAS: We went to China Airlines 616 00:33:56,167 --> 00:34:01,406 to ask them to demonstrate how they do the maintenance work. 617 00:34:01,472 --> 00:34:03,074 THOMAS: Do you think you can show me how you completed 618 00:34:03,141 --> 00:34:06,577 this repair on the downstop assembly? 619 00:34:06,644 --> 00:34:08,479 BOB: Sometimes maintenance records don't tell you 620 00:34:08,546 --> 00:34:09,614 the true story. 621 00:34:09,680 --> 00:34:12,216 They can tell you that according to somebody, 622 00:34:12,283 --> 00:34:15,119 a maintenance procedure had been done correctly. 623 00:34:15,186 --> 00:34:16,354 But to get a better story, 624 00:34:16,421 --> 00:34:20,324 you have to actually watch the procedure being done. 625 00:34:20,391 --> 00:34:21,292 NARRATOR: A mechanic demonstrates 626 00:34:21,359 --> 00:34:26,898 how he performed the downstop repair. 627 00:34:26,964 --> 00:34:32,870 MECHANIC: You won't be able to see much of what I'm doing. 628 00:34:32,937 --> 00:34:36,507 RODNEY: Performing maintenance on this particular downstop 629 00:34:36,574 --> 00:34:40,178 is a little tricky. 630 00:34:40,244 --> 00:34:45,383 The mechanic is going to be in a very restricted visual area. 631 00:34:45,450 --> 00:34:48,119 So he's going to have to work with his hands. 632 00:34:48,186 --> 00:34:53,958 He's going to have to feel the apparatus. 633 00:34:54,025 --> 00:34:58,563 MECHANIC: After applying glue, you put the bolt into place. 634 00:34:58,629 --> 00:35:00,565 ♪ 635 00:35:00,631 --> 00:35:03,668 THOMAS: You can imagine that you're under the wing 636 00:35:03,734 --> 00:35:05,236 and you cannot see it. 637 00:35:17,515 --> 00:35:20,685 MECHANIC: Sorry. I just dropped it. Don't worry. 638 00:35:20,751 --> 00:35:23,254 It's easy to pick up again. 639 00:35:31,462 --> 00:35:34,532 NARRATOR: It's an eye-opening demonstration. 640 00:35:34,599 --> 00:35:36,601 MECHANIC: And that's how it's done. 641 00:35:36,667 --> 00:35:39,570 THOMAS: Thank you. You have been very helpful. 642 00:35:39,637 --> 00:35:42,607 THOMAS: It's not very easy for them to confirm 643 00:35:42,673 --> 00:35:47,044 they finished their job and everything is in order there. 644 00:35:47,111 --> 00:35:50,982 ♪ 645 00:35:51,048 --> 00:35:53,518 NARRATOR: Records show that the work order repair 646 00:35:53,584 --> 00:35:56,621 was the only time mechanics ever serviced the downstop 647 00:35:56,687 --> 00:36:00,992 in the history of the accident airplane. 648 00:36:01,058 --> 00:36:02,960 There's only one possible explanation 649 00:36:03,027 --> 00:36:08,065 for how the washer found in Okinawa came loose. 650 00:36:08,132 --> 00:36:12,770 It fell off during the maintenance procedure in Taiwan. 651 00:36:12,837 --> 00:36:15,106 BOB: It could have just slipped off the gentleman's fingers 652 00:36:15,172 --> 00:36:19,810 when he was trying to install it. 653 00:36:19,877 --> 00:36:22,179 It could have stuck to the nut and then fallen off 654 00:36:22,246 --> 00:36:25,950 just before he touched them together. 655 00:36:26,017 --> 00:36:27,585 A lot of things could have happened. 656 00:36:27,652 --> 00:36:34,225 The bottom line is, the washer was not there. 657 00:36:34,292 --> 00:36:40,531 ♪ 658 00:36:40,598 --> 00:36:42,867 NARRATOR: But understanding what happened to the washer 659 00:36:42,934 --> 00:36:46,737 still leaves investigators scratching their heads. 660 00:36:46,804 --> 00:36:49,473 The downstop assembly had a well-tightened nut 661 00:36:49,540 --> 00:36:53,544 that was also glued to the bolt. How could it fall out? 662 00:36:58,950 --> 00:37:01,752 And how did this piece start a raging fuel fire 663 00:37:01,819 --> 00:37:04,221 that destroyed a $70 million airplane 664 00:37:04,288 --> 00:37:07,291 and threatened the lives of 165 people? 665 00:37:11,629 --> 00:37:12,897 ♪ 666 00:37:12,964 --> 00:37:18,269 THOMAS: All right. Now let's test it without a washer. 667 00:37:18,336 --> 00:37:20,972 NARRATOR: Investigators experiment with the suspicious part 668 00:37:21,038 --> 00:37:24,976 from Flight 120 to see how it performs without the washer. 669 00:37:25,042 --> 00:37:28,145 RODNEY: The design of this assembly requires each component 670 00:37:28,212 --> 00:37:29,680 to play a specific role. 671 00:37:29,747 --> 00:37:37,221 So any piece that is not reinstalled is critical. 672 00:37:37,288 --> 00:37:39,790 NARRATOR: They make a stunning discovery. 673 00:37:44,528 --> 00:37:46,330 The small washer is the only thing 674 00:37:46,397 --> 00:37:50,401 preventing the unit from falling out of its mount. 675 00:37:50,468 --> 00:37:55,272 THOMAS: Without the washer, it fails. 676 00:37:55,339 --> 00:37:57,141 BOB: We discovered that the nut and the bolt 677 00:37:57,208 --> 00:37:59,810 were smaller than the rest of the assembly 678 00:37:59,877 --> 00:38:06,550 and that the washer was a required item. 679 00:38:06,617 --> 00:38:09,887 This is an example of an intact downstop assembly. 680 00:38:09,954 --> 00:38:16,027 You take the nut off. You take the washer off. 681 00:38:16,093 --> 00:38:20,164 Put the nut back on, like they did in Taiwan, 682 00:38:20,231 --> 00:38:22,400 and now you'll note that the assembly itself 683 00:38:22,466 --> 00:38:24,535 is pretty ineffective. 684 00:38:24,602 --> 00:38:30,207 It falls apart without much problem at all. 685 00:38:30,274 --> 00:38:31,509 ♪ 686 00:38:31,575 --> 00:38:34,311 NARRATOR: Finally, it's clear why the downstop assembly 687 00:38:34,378 --> 00:38:37,948 was able to fall out of the slat track. 688 00:38:38,015 --> 00:38:39,717 How it punctured the fuel tank 689 00:38:39,784 --> 00:38:42,787 is the final piece of the puzzle. 690 00:38:42,853 --> 00:38:44,021 But investigators believe 691 00:38:44,088 --> 00:38:48,959 the design of the slat mechanism itself may hold the answer. 692 00:38:49,026 --> 00:38:51,128 RODNEY: When the engineers are designing these aircraft, 693 00:38:51,195 --> 00:38:55,066 they take into consideration maximum space utilization 694 00:38:55,132 --> 00:38:58,135 and for the design of a leading edge slat 695 00:38:58,202 --> 00:39:00,938 they came up with something called a can. 696 00:39:01,005 --> 00:39:03,407 NARRATOR: The slat can is the area inside the wing 697 00:39:03,474 --> 00:39:06,410 that houses the moving track. 698 00:39:06,477 --> 00:39:11,916 RODNEY: The can is a void that extends into the fuel tank 699 00:39:11,982 --> 00:39:15,686 and allows for the device that operates the slat 700 00:39:15,753 --> 00:39:18,189 to move in and out. 701 00:39:18,255 --> 00:39:20,825 NARRATOR: The space inside the slat can is tight, 702 00:39:20,891 --> 00:39:24,795 just big enough for the sliding track. 703 00:39:24,862 --> 00:39:28,532 Any foreign metal object taking up any space inside the can 704 00:39:28,599 --> 00:39:31,669 would be an accident waiting to happen. 705 00:39:31,736 --> 00:39:34,138 BOB: It would render the entire assembly 706 00:39:34,205 --> 00:39:37,575 not only non-functional but dangerous. 707 00:39:44,882 --> 00:39:46,217 ♪ 708 00:39:46,283 --> 00:39:49,487 THOMAS: China Airlines flight 1-2-0, 709 00:39:49,553 --> 00:39:54,425 157 passengers, eight crew. 710 00:39:54,492 --> 00:39:57,061 NARRATOR: Investigators believe they finally understand 711 00:39:57,128 --> 00:40:00,498 the sequence of events that led to a devastating fuel fire 712 00:40:00,564 --> 00:40:04,235 in Okinawa. 713 00:40:04,301 --> 00:40:07,138 ♪ 714 00:40:07,204 --> 00:40:09,673 It all begins weeks before the accident 715 00:40:09,740 --> 00:40:14,145 with a botched repair to a critical component. 716 00:40:15,880 --> 00:40:21,952 A single missing washer turns a downstop into a hidden danger, 717 00:40:22,019 --> 00:40:25,523 a bolt that can work its way loose over time. 718 00:40:27,057 --> 00:40:28,893 BOB: Washers really aren't supposed to hold things together, 719 00:40:28,959 --> 00:40:31,629 but this washer did because of its design. 720 00:40:38,269 --> 00:40:41,105 NARRATOR: Six weeks after the failed repair... 721 00:40:41,172 --> 00:40:43,274 CPT. YU: Please give the flight attendants your full cooperation 722 00:40:43,340 --> 00:40:45,643 as they prepare the cabin for landing. 723 00:40:45,709 --> 00:40:48,846 NARRATOR: A routine descent into Okinawa requires the pilots 724 00:40:48,913 --> 00:40:51,916 to deploy the flaps and slats as usual. 725 00:40:55,920 --> 00:40:58,923 Inside one of the track cans on the right wing, 726 00:40:58,989 --> 00:41:04,829 the loosened downstop is just barely holding on. 727 00:41:04,895 --> 00:41:06,263 Touchdown is enough of a jolt 728 00:41:06,330 --> 00:41:11,135 to finally knock the downstop out of its track. 729 00:41:11,202 --> 00:41:13,037 CPT. YU: Flaps up. 730 00:41:13,103 --> 00:41:15,272 NARRATOR: The unsuspecting crew soon retracts 731 00:41:15,339 --> 00:41:17,808 the flaps and slats. 732 00:41:17,875 --> 00:41:20,511 The plane's powerful hydraulics move the slat track 733 00:41:20,578 --> 00:41:26,183 back into the can. But now the downstop bolt is in the way. 734 00:41:26,250 --> 00:41:28,819 The track pushes it to the back of the can and then 735 00:41:28,886 --> 00:41:32,890 straight through, puncturing the right wing fuel tank. 736 00:41:37,027 --> 00:41:42,299 THOMAS: A hole in the fuel tank caused the leak. 737 00:41:42,366 --> 00:41:44,235 The plane would have been carrying 738 00:41:44,301 --> 00:41:47,338 thousands of liters of fuel. 739 00:41:47,404 --> 00:41:49,740 NARRATOR: As the plane taxis, the engine exhaust 740 00:41:49,807 --> 00:41:53,344 is powerful enough to disperse the leaking fuel. 741 00:41:53,410 --> 00:41:57,214 It can't come in contact with the hot tail pipe or brakes. 742 00:41:57,281 --> 00:42:00,751 CPT. YU: After-landing checklist. 743 00:42:00,818 --> 00:42:04,188 NARRATOR: But once the pilots park and shut down the engines, 744 00:42:04,255 --> 00:42:07,691 the situation instantly becomes much more dangerous. 745 00:42:07,758 --> 00:42:09,293 FO. TSENG: Engine start levers. 746 00:42:09,360 --> 00:42:13,063 CPT. YU: Engine start levers cut off. 747 00:42:13,130 --> 00:42:14,565 NARRATOR: The leaking fuel starts dripping 748 00:42:14,632 --> 00:42:18,969 directly onto the scorching-hot tail pipe. 749 00:42:19,036 --> 00:42:21,305 PASSENGERS: 750 00:42:21,372 --> 00:42:24,174 JIM: What is going on out there? 751 00:42:24,241 --> 00:42:27,211 NARRATOR: The leaking jet fuel ignites on contact. 752 00:42:27,278 --> 00:42:30,014 KIT: The speed of the development of the fire is incredible. 753 00:42:30,080 --> 00:42:35,519 Obviously fuel burns very well, and it goes up like a bomb. 754 00:42:35,586 --> 00:42:37,321 FLIGHT ATTENDANT: Everybody remain calm. 755 00:42:37,388 --> 00:42:39,323 NARRATOR: The cabin crew's professional conduct 756 00:42:39,390 --> 00:42:42,092 gets 157 passengers off the plane 757 00:42:42,159 --> 00:42:47,965 in just one minute and 42 seconds. 758 00:42:48,032 --> 00:42:50,968 ♪ 759 00:42:51,035 --> 00:42:53,304 The Naha Airport fire leads investigators 760 00:42:53,370 --> 00:42:57,207 to a striking realization. 761 00:42:57,274 --> 00:43:04,248 THOMAS: The repair that was ordered actually caused the fire. 762 00:43:04,315 --> 00:43:05,349 BOB: It was kind of ironic. 763 00:43:05,416 --> 00:43:08,185 The Taiwanese maintenance procedure was to prevent 764 00:43:08,252 --> 00:43:11,889 an accident, and in essence the procedure had a lot to do 765 00:43:11,956 --> 00:43:16,026 with why this particular accident happened. 766 00:43:16,093 --> 00:43:18,963 KIT: It's a great study in unintended consequences. 767 00:43:19,029 --> 00:43:21,465 We really were trying to fix a problem. 768 00:43:21,532 --> 00:43:23,334 We really didn't anticipate that 769 00:43:23,400 --> 00:43:26,203 every time we handle a maintenance piece like this 770 00:43:26,270 --> 00:43:30,107 there is a risk. And it bit us. 771 00:43:30,174 --> 00:43:32,643 NARRATOR: In the wake of the Naha Airport inferno, 772 00:43:32,710 --> 00:43:34,778 aviation authorities around the world 773 00:43:34,845 --> 00:43:38,716 order the inspection of the entire fleet of 737s. 774 00:43:38,782 --> 00:43:42,753 In the US alone, 21 planes are found to have the same defect, 775 00:43:42,820 --> 00:43:46,890 all of them at risk of a catastrophic fuel leak and fire. 776 00:43:46,957 --> 00:43:48,692 Boeing takes immediate action. 777 00:43:48,759 --> 00:43:50,928 It redesigns the downstop mechanism 778 00:43:50,995 --> 00:43:53,497 and ensures that the improved part is installed 779 00:43:53,564 --> 00:43:55,599 on each and every plane. 780 00:43:55,666 --> 00:43:57,267 KIT: Boeing made the changes necessary 781 00:43:57,334 --> 00:44:00,637 to ensure that the accident didn't occur again. 782 00:44:00,704 --> 00:44:02,373 It took a little time, as it normally does, 783 00:44:02,439 --> 00:44:04,408 to get to the final resolution of it, 784 00:44:04,475 --> 00:44:05,943 but they did what they needed to do. 785 00:44:06,010 --> 00:44:08,512 ♪