1 00:00:03,136 --> 00:00:04,871 Grab your ankles. Head down. 2 00:00:05,672 --> 00:00:06,606 Man: Get out of it! 3 00:00:06,673 --> 00:00:08,341 Man: I can't. Man: no! 4 00:00:08,408 --> 00:00:10,610 Man: Oh, God! That's it. 5 00:00:13,880 --> 00:00:17,650 Narrator: A plane crash in Georgia leaves 23 dead, 6 00:00:17,717 --> 00:00:21,321 including a NASA astronaut and a U.S. Senator. 7 00:00:21,721 --> 00:00:23,690 Man: Anytime there's a high-profile case, 8 00:00:23,757 --> 00:00:26,826 there's more stress and pressure on you. 9 00:00:26,893 --> 00:00:28,561 Narrator: In search of the cause... 10 00:00:28,628 --> 00:00:30,563 Man: We've got to see what happens in the air. 11 00:00:30,630 --> 00:00:32,499 Narrator: Investigator Tom Haueter gambles 12 00:00:32,565 --> 00:00:34,167 on a risky hunch. 13 00:00:34,234 --> 00:00:36,336 Tom Haueter: When I first proposed doing the flight test, 14 00:00:36,403 --> 00:00:38,671 it was not well-received. 15 00:00:38,738 --> 00:00:41,174 Narrator: He puts his reputation 16 00:00:41,241 --> 00:00:44,477 and the life of a skilled test pilot on the line. 17 00:00:44,544 --> 00:00:45,945 Haueter: EMB-120, do you copy? 18 00:00:46,012 --> 00:00:47,147 Man: Copy. 19 00:00:47,781 --> 00:00:51,284 Man: This was, in my opinion, a very dangerous maneuver. 20 00:00:51,351 --> 00:00:53,653 Haueter: What if this airplane crashes? 21 00:00:53,720 --> 00:00:55,321 What if we lose the airplane? 22 00:00:55,922 --> 00:00:58,091 Man: The risks, of course, is part of the game. 23 00:01:00,827 --> 00:01:02,128 Flight attendant: Ladies and gentlemen, 24 00:01:02,195 --> 00:01:03,229 we are starting our approach. 25 00:01:03,296 --> 00:01:04,764 Pilot: We lost both engines! 26 00:01:04,831 --> 00:01:05,899 Flight attendant: Put the mask over your nose. 27 00:01:05,965 --> 00:01:06,900 Emergency descent. 28 00:01:06,966 --> 00:01:08,268 Pilot: Mayday, mayday. 29 00:01:08,334 --> 00:01:09,369 Flight attendant: Brace for impact! 30 00:01:09,436 --> 00:01:10,937 Controller: I think I lost one. 31 00:01:11,004 --> 00:01:13,440 Man: Investigation starting into this tragedy... 32 00:01:13,506 --> 00:01:15,341 Man: He's gonna crash! 33 00:01:28,021 --> 00:01:31,624 Narrator: Atlantic Southeast Airlines flight 2311 34 00:01:31,691 --> 00:01:33,827 cruises at 15,000 feet. 35 00:01:37,030 --> 00:01:39,232 Hank Johnston: It's the Braves' year. I feel it. 36 00:01:39,299 --> 00:01:41,501 Mark Friedline: Sorry. I don't want to get my hopes up. 37 00:01:41,568 --> 00:01:45,238 Last year still hurts. 38 00:01:45,305 --> 00:01:48,975 Narrator: At the controls is Captain Mark Friedline. 39 00:01:49,042 --> 00:01:51,544 The 34-year-old is an experienced pilot 40 00:01:51,611 --> 00:01:54,614 with almost 12,000 flight hours. 41 00:01:55,915 --> 00:01:57,917 Friedline: We got storm clouds ahead of us. 42 00:01:57,984 --> 00:02:00,153 Johnston: Yep. What do you want to do? 43 00:02:00,753 --> 00:02:03,189 Narrator: First officer Hank Johnston is 36. 44 00:02:03,256 --> 00:02:05,658 He's been flying with Atlantic Southeast Airlines 45 00:02:05,725 --> 00:02:08,461 for nearly three years. 46 00:02:09,662 --> 00:02:11,197 Friedline: We're gonna go around 'em. 47 00:02:11,698 --> 00:02:14,200 Tell center we'll go right. 48 00:02:14,267 --> 00:02:15,969 Johnston: Center, ASA 2311. 49 00:02:16,035 --> 00:02:19,172 We'd like to request a deviation for some weather. 50 00:02:19,739 --> 00:02:21,040 John Maris: This was a normal day 51 00:02:21,107 --> 00:02:22,876 in the life of the crew. 52 00:02:22,942 --> 00:02:24,711 Nothing untoward had happened, 53 00:02:24,777 --> 00:02:26,479 and I doubt they were expecting any difficulties 54 00:02:26,546 --> 00:02:27,814 with the flight. 55 00:02:27,881 --> 00:02:30,083 Controller: ASA 2311, roger that. 56 00:02:30,149 --> 00:02:32,785 Weather deviation approved at your discretions. 57 00:02:32,852 --> 00:02:34,287 Maintain current altitude. 58 00:02:35,121 --> 00:02:37,690 Johnston: Okay. Thanks, center. 2311. 59 00:02:37,757 --> 00:02:40,960 Friedline: Let's go... 20 degrees to the right. 60 00:02:44,230 --> 00:02:46,165 Narrator: Today's flight is a short commuter route 61 00:02:46,232 --> 00:02:47,767 from Atlanta, Georgia, 62 00:02:47,834 --> 00:02:50,503 to the city of Brunswick on the Atlantic coast. 63 00:02:54,140 --> 00:02:56,142 Friedline: This is Captain Friedline on the flight deck. 64 00:02:56,209 --> 00:02:58,111 We've got a bit of weather ahead of us, 65 00:02:58,177 --> 00:03:00,713 but we're gonna go around it and give you a pretty smooth ride. 66 00:03:00,780 --> 00:03:02,582 Might hit a few bumps, but nothing to worry about. 67 00:03:02,649 --> 00:03:04,717 We do ask you to return to your seats 68 00:03:04,784 --> 00:03:07,353 and please make sure your safety belts are fastened. 69 00:03:12,892 --> 00:03:15,128 Narrator: The Embraer 120 banks gently 70 00:03:15,194 --> 00:03:18,231 as the pilots deviate around the storm. 71 00:03:20,300 --> 00:03:21,701 Maris: The Embraer EMB-120 72 00:03:21,768 --> 00:03:24,203 is designed for commuter-type operations. 73 00:03:24,270 --> 00:03:27,507 It takes approximately 30 people on short haul flights 74 00:03:27,574 --> 00:03:30,176 between city centers. 75 00:03:30,243 --> 00:03:31,544 Narrator: The commuter airplane 76 00:03:31,611 --> 00:03:34,147 is powered by two turboprop engines. 77 00:03:35,615 --> 00:03:37,917 Maris: Turboprops differ from jet engines 78 00:03:37,984 --> 00:03:40,753 because instead of using the exhaust to power the aircraft, 79 00:03:40,820 --> 00:03:42,889 they use a propeller, which is more fuel-efficient 80 00:03:42,956 --> 00:03:46,926 and is more suited for these smaller aircraft. 81 00:03:47,827 --> 00:03:49,996 Narrator: Today, there are 20 passengers aboard, 82 00:03:50,063 --> 00:03:52,966 including NASA Astronaut Sonny Carter. 83 00:03:54,601 --> 00:03:56,502 Sonny Carter: Thank you so much. 84 00:03:56,569 --> 00:03:58,438 You're a star. 85 00:03:58,871 --> 00:04:01,341 Narrator: As part of the space shuttle Discovery's crew, 86 00:04:01,407 --> 00:04:04,911 Sonny Carter orbited the Earth for 120 hours, 87 00:04:04,978 --> 00:04:08,548 circling the planet 79 times. 88 00:04:09,983 --> 00:04:13,753 Frederick Gregory served with Carter on that mission. 89 00:04:13,820 --> 00:04:15,421 Fred Gregory: Sonny was not only an astronaut; 90 00:04:15,488 --> 00:04:17,256 he was a renaissance man. 91 00:04:17,323 --> 00:04:20,693 He was an engineer, he was a medical doctor, 92 00:04:20,760 --> 00:04:23,696 he was a navy pilot. 93 00:04:23,763 --> 00:04:26,699 At a very young age, he had accomplished things 94 00:04:26,766 --> 00:04:28,334 that even one of which would have been 95 00:04:28,401 --> 00:04:33,373 an outstanding achievement for just any other person. 96 00:04:33,439 --> 00:04:36,676 Narrator: Also on the flight is another high-profile figure, 97 00:04:36,743 --> 00:04:39,245 former Senator John Tower. 98 00:04:40,747 --> 00:04:43,650 Tower served four terms in the U.S. Senate. 99 00:04:44,217 --> 00:04:46,052 A leading republican, he was an advisor 100 00:04:46,119 --> 00:04:50,556 to presidents Ronald Reagan and George H.W. Bush. 101 00:04:52,759 --> 00:04:55,428 Friedline: We're still running 20 minutes late. 102 00:04:55,495 --> 00:04:57,330 Johnston: Yep. Well... 103 00:04:57,730 --> 00:04:59,465 Friedline: Couldn't be helped. 104 00:05:00,333 --> 00:05:03,436 Narrator: Before takeoff, flight 2311 was delayed 105 00:05:03,503 --> 00:05:05,638 due to a mechanical problem. 106 00:05:06,606 --> 00:05:09,442 The crew was forced to switch planes. 107 00:05:10,243 --> 00:05:13,246 Maris: There was a last-minute change in the aircraft, 108 00:05:13,312 --> 00:05:15,548 which, while uncommon, is not extraordinary, 109 00:05:15,615 --> 00:05:18,918 and it would not have thrown the crew. 110 00:05:22,922 --> 00:05:26,592 Carter: These small planes do keep you on your toes. 111 00:05:28,294 --> 00:05:29,829 Narrator: The new plane is running smoothly 112 00:05:29,896 --> 00:05:31,864 as it leaves the storm clouds behind 113 00:05:31,931 --> 00:05:34,067 and nears its destination. 114 00:05:37,603 --> 00:05:42,141 Glynco Airport is a former air base with just one runway. 115 00:05:42,208 --> 00:05:45,545 It's used by private planes and small commuter airlines 116 00:05:45,611 --> 00:05:47,847 flying to the Georgia coast. 117 00:05:49,449 --> 00:05:52,618 The flight attendant prepares the cabin for landing. 118 00:05:54,153 --> 00:05:56,656 Friedline: The runway's in sight. 119 00:05:57,190 --> 00:06:00,426 Narrator: The crew is just five minutes from touching down. 120 00:06:01,227 --> 00:06:05,631 Controller: ASA 2311, cleared direct to Jeff-1 Glynco. 121 00:06:05,698 --> 00:06:08,768 Report the airport in sight. Expect a visual. 122 00:06:08,835 --> 00:06:11,504 Johnston: We do have it in sight, 2311. 123 00:06:12,138 --> 00:06:14,240 Friedline: Slowing for approach speed. 124 00:06:15,775 --> 00:06:16,943 Maris: The aircraft was normal. 125 00:06:17,009 --> 00:06:19,545 There was nothing unexpected. 126 00:06:19,612 --> 00:06:20,980 Friedline: Gear down. 127 00:06:23,549 --> 00:06:24,784 Johnston: Gear down. 128 00:06:25,785 --> 00:06:27,253 Three green. 129 00:06:30,056 --> 00:06:32,792 Narrator: Then, the captain notices an unusual sound. 130 00:06:34,761 --> 00:06:36,629 Friedline: That's weird. 131 00:06:36,696 --> 00:06:39,432 Number one seems to be spinning faster. 132 00:06:39,499 --> 00:06:44,403 The left is... the left is pulling a bit more. 133 00:06:44,470 --> 00:06:47,073 Bringing power down to the left. 134 00:06:47,140 --> 00:06:49,442 Narrator: Captain Friedline tries to compensate 135 00:06:49,509 --> 00:06:52,745 for the plane's unexplained pull to the left. 136 00:06:54,514 --> 00:06:59,018 Flight 2311 is less than 1,000 feet from the ground, 137 00:06:59,552 --> 00:07:02,755 and the plane is getting more and more difficult to control. 138 00:07:06,592 --> 00:07:07,727 Friedline: What's going on? 139 00:07:07,794 --> 00:07:09,295 You see anything? 140 00:07:10,196 --> 00:07:11,998 Johnston: There's nothing. 141 00:07:12,064 --> 00:07:13,666 Maris: The crew were apparently caught completely by surprise 142 00:07:13,733 --> 00:07:15,067 by something. 143 00:07:15,134 --> 00:07:16,169 Friedline: What's going on with this thing? 144 00:07:16,235 --> 00:07:17,270 I can't hold it. 145 00:07:17,336 --> 00:07:18,604 Johnston: Get out of it! 146 00:07:18,671 --> 00:07:20,473 Friedline: I can't. Come on! 147 00:07:22,008 --> 00:07:24,443 Narrator: The plane is rolling to the left, 148 00:07:24,510 --> 00:07:27,113 and the crew doesn't know why. 149 00:07:27,947 --> 00:07:29,982 Maris: The crew would have instinctively applied 150 00:07:30,049 --> 00:07:32,919 opposite aileron, moving the stick to the right, 151 00:07:32,985 --> 00:07:34,954 to try and prevent the aircraft from rolling as it was. 152 00:07:38,591 --> 00:07:41,527 Carter: Come on, guys. 153 00:07:41,594 --> 00:07:42,995 Get us out of this. 154 00:07:43,062 --> 00:07:45,331 Johnston: Come on! God. I can't. 155 00:07:45,398 --> 00:07:46,899 Computer: pull up. 156 00:07:46,966 --> 00:07:49,001 Maris: I think they would have been preoccupied 157 00:07:49,068 --> 00:07:51,671 with trying to stop the roll, 158 00:07:51,737 --> 00:07:53,172 maybe to the extent of not knowing 159 00:07:53,239 --> 00:07:55,775 just how much peril they were in. 160 00:07:57,910 --> 00:07:59,111 Carter: Do what I do. 161 00:07:59,178 --> 00:08:01,447 Grab your ankles, head down. Okay? 162 00:08:03,416 --> 00:08:05,017 Narrator: Captain Friedline fights desperately 163 00:08:05,084 --> 00:08:06,552 to save his plane. 164 00:08:06,619 --> 00:08:07,720 Computer: Pull up. 165 00:08:08,054 --> 00:08:10,223 Friedline: Come on! Johnston: No! No! 166 00:08:10,289 --> 00:08:13,326 Friedline: That's it. Oh, God! 167 00:08:13,392 --> 00:08:15,228 Narrator: It's no use. 168 00:08:19,732 --> 00:08:22,335 Maris: The aircraft crashed in the middle of woods, 169 00:08:22,401 --> 00:08:24,437 which would have made the job of the first responders 170 00:08:24,503 --> 00:08:27,907 and firefighting teams quite difficult. 171 00:08:29,475 --> 00:08:32,979 Narrator: Rescuers make their way through the dense brush, 172 00:08:33,045 --> 00:08:35,248 but when they reach the crash site, 173 00:08:35,314 --> 00:08:38,150 they find no one alive to rescue. 174 00:08:39,318 --> 00:08:43,055 All 20 passengers and three crewmembers are dead, 175 00:08:43,122 --> 00:08:45,524 killed at the moment of impact. 176 00:08:47,627 --> 00:08:49,095 Jim Ritter: It was a catastrophic crash. 177 00:08:49,161 --> 00:08:51,831 There was no chance for survival. 178 00:08:53,232 --> 00:08:56,235 Narrator: With two high-profile passengers on board, 179 00:08:56,302 --> 00:09:00,273 the crash of flight 2311 makes headlines around the world. 180 00:09:03,376 --> 00:09:05,211 Maris: In this particular accident, 181 00:09:05,278 --> 00:09:09,215 Senator Tower on board, was a four-term senator, was killed, 182 00:09:09,282 --> 00:09:12,084 which raised the profile of the accident a great deal, 183 00:09:12,151 --> 00:09:13,653 both from the investigation point of view 184 00:09:13,719 --> 00:09:15,922 and the public and the media. 185 00:09:15,988 --> 00:09:17,657 Woman: And we are, at this moment, 186 00:09:17,723 --> 00:09:21,294 beginning the on-scene phases of the investigation. 187 00:09:22,028 --> 00:09:27,133 Gregory: I was in Spain when the accident occurred. 188 00:09:27,199 --> 00:09:29,535 When I got on the plane to head back, 189 00:09:29,602 --> 00:09:33,839 the pilot told me that one of the astronauts had been killed, 190 00:09:33,906 --> 00:09:36,242 and that his name was Carter. 191 00:09:36,943 --> 00:09:40,279 I was in shock, because Sonny and I had 192 00:09:40,346 --> 00:09:44,517 had an amazing relationship for years. 193 00:09:44,583 --> 00:09:46,218 We were like brothers. 194 00:09:51,590 --> 00:09:53,125 Narrator: Wreckage is still smoldering 195 00:09:53,192 --> 00:09:55,962 when Jim Ritter arrives at the crash site. 196 00:09:57,964 --> 00:09:59,966 Though an experienced investigator 197 00:10:00,032 --> 00:10:02,134 with the national transportation safety board, 198 00:10:02,201 --> 00:10:05,304 Ritter is struck by what he sees. 199 00:10:05,571 --> 00:10:06,906 Ritter: My God. 200 00:10:09,041 --> 00:10:11,377 There was a lot of fire damage in the wreckage, 201 00:10:11,444 --> 00:10:15,448 and the airplane was basically totally destroyed. 202 00:10:17,049 --> 00:10:18,684 Narrator: Ritter realizes he's facing 203 00:10:18,751 --> 00:10:21,287 one of the biggest challenges of his career. 204 00:10:22,088 --> 00:10:24,724 Ritter: Anytime there's a high-profile case, 205 00:10:24,790 --> 00:10:26,192 you're a little more nervous. 206 00:10:26,258 --> 00:10:28,627 There's more stress and pressure on you 207 00:10:28,694 --> 00:10:32,865 to come up with a cause for the accident. 208 00:10:32,932 --> 00:10:35,634 Narrator: The pressure is on to figure out what happened 209 00:10:35,701 --> 00:10:37,670 aboard flight 2311. 210 00:10:48,447 --> 00:10:49,882 Narrator: In Glynn county, Georgia, 211 00:10:49,949 --> 00:10:51,784 investigators search for answers 212 00:10:51,851 --> 00:10:55,154 at the crash site of flight 2311. 213 00:10:55,788 --> 00:10:57,656 Several people at a nearby trailer park 214 00:10:57,723 --> 00:10:59,558 saw the plane go down. 215 00:11:00,659 --> 00:11:02,495 Man: It had come right over top of the house, 216 00:11:02,561 --> 00:11:03,996 and it got real loud. 217 00:11:04,063 --> 00:11:06,499 It was coming right over these trees here, 218 00:11:06,565 --> 00:11:09,668 and then it got extra loud. 219 00:11:11,404 --> 00:11:14,673 Ritter: The eyewitnesses saw an extreme left roll angle 220 00:11:14,740 --> 00:11:16,409 from the airplane, 221 00:11:16,475 --> 00:11:19,779 and so we knew that it was some kind of catastrophic failure, 222 00:11:19,845 --> 00:11:23,182 a very abrupt failure that would have been difficult 223 00:11:23,249 --> 00:11:25,651 for the flight crew to overcome. 224 00:11:26,519 --> 00:11:28,087 Okay. 225 00:11:28,154 --> 00:11:30,222 Let's start here and work backwards to first impact. 226 00:11:30,289 --> 00:11:31,924 I want a record of everything. 227 00:11:32,758 --> 00:11:34,093 You need to look at the crash site 228 00:11:34,160 --> 00:11:36,362 to collect the physical evidence. 229 00:11:36,429 --> 00:11:38,597 That's the most important aspect 230 00:11:38,664 --> 00:11:42,835 of any aircraft investigation. 231 00:11:42,902 --> 00:11:44,537 Maris: Investigators look at the wreckage 232 00:11:44,603 --> 00:11:47,940 to try and evaluate the sequence of events leading to the crash. 233 00:11:48,007 --> 00:11:50,209 They look for the two wing tips, the tip of the tail, 234 00:11:50,276 --> 00:11:51,877 the tip of the nose. 235 00:11:53,312 --> 00:11:55,748 Narrator: A survey of the crash site soon confirms 236 00:11:55,815 --> 00:12:00,086 those key pieces are among the wreckage. 237 00:12:00,152 --> 00:12:02,922 Ritter: That tells us that there was no in-flight breakup 238 00:12:02,988 --> 00:12:05,658 and that the airplane stayed intact 239 00:12:05,724 --> 00:12:08,227 until it collided with the ground. 240 00:12:09,762 --> 00:12:12,064 Can you get a shot of this wing for me, please? 241 00:12:12,131 --> 00:12:13,933 Narrator: For expert investigators, 242 00:12:13,999 --> 00:12:18,170 the size and shape of the impact zone is also a clue. 243 00:12:20,306 --> 00:12:21,874 Maris: If an aircraft, particularly through trees, 244 00:12:21,941 --> 00:12:24,543 has a long swathe cut through the trees, 245 00:12:24,610 --> 00:12:27,546 the investigators get an idea that the aircraft hit the ground 246 00:12:27,613 --> 00:12:30,549 approximately flat in a shallow descent. 247 00:12:31,183 --> 00:12:32,952 In this case, the wreckage was very concentrated, 248 00:12:33,018 --> 00:12:34,887 which indicated the aircraft hit the ground 249 00:12:34,954 --> 00:12:37,690 at a very steep angle. 250 00:12:38,290 --> 00:12:40,759 Ritter: We need to get some 251 00:12:38,290 --> 00:12:40,759 measurements on these trees. 252 00:12:41,961 --> 00:12:44,563 Narrator: Investigators hope the broken trees will shed light 253 00:12:44,630 --> 00:12:48,667 on witness statements about the way the plane was flying. 254 00:12:48,734 --> 00:12:51,137 Man: I seen it fly overhead and, you know, 255 00:12:51,203 --> 00:12:53,005 it looked like it was making a wide right turn, 256 00:12:53,072 --> 00:12:55,941 but it was unusual because when it turned out, 257 00:12:56,008 --> 00:12:58,277 it... the nose started heading toward the ground, 258 00:12:58,344 --> 00:13:01,313 and I was right up toward the entrance of touchstone, 259 00:13:01,380 --> 00:13:04,650 and I heard the explosion and seen the fire and the smoke. 260 00:13:06,685 --> 00:13:08,354 Ritter: When the plane crashed, 261 00:13:08,420 --> 00:13:12,224 it sheared the tops off of many of the trees in the woods there, 262 00:13:12,291 --> 00:13:14,660 and so one of the things that we did 263 00:13:14,727 --> 00:13:16,729 was we measured the heights of the trees 264 00:13:16,795 --> 00:13:18,697 where the tops were sheared off, 265 00:13:18,764 --> 00:13:21,300 and that was able to give us a fairly good idea 266 00:13:21,367 --> 00:13:25,638 of the roll angle, which was a large left roll. 267 00:13:28,474 --> 00:13:30,876 In the plane you would have felt light in your seat. 268 00:13:30,943 --> 00:13:33,279 You would have turned obviously to the left 269 00:13:33,345 --> 00:13:34,647 at almost 90 degrees. 270 00:13:34,713 --> 00:13:35,748 Johnston: Get out of it! 271 00:13:35,814 --> 00:13:37,816 Friedline: I can't. Come on! 272 00:13:37,883 --> 00:13:40,252 Ritter: It would have been a traumatic experience. 273 00:13:40,319 --> 00:13:42,755 Carter: Come on, guys. 274 00:13:42,821 --> 00:13:44,790 Get us out of this. 275 00:13:49,995 --> 00:13:52,264 Ritter: What could make it roll so far over? 276 00:13:53,065 --> 00:13:54,667 When the airplane rolled to the left, 277 00:13:54,733 --> 00:13:57,770 it could really only be due to two things. 278 00:13:57,836 --> 00:14:00,272 Perhaps the pilot wanted to roll to the left, 279 00:14:00,339 --> 00:14:04,577 or there was a malfunction that the pilots couldn't counteract. 280 00:14:05,077 --> 00:14:06,512 What have you got for me? 281 00:14:07,546 --> 00:14:09,815 Narrator: Ritter examines 282 00:14:07,546 --> 00:14:09,815 airport flight records. 283 00:14:10,516 --> 00:14:12,685 He's looking for anything that might have triggered 284 00:14:12,751 --> 00:14:14,820 the deadly roll. 285 00:14:14,887 --> 00:14:16,689 Ritter: Clear skies on approach. 286 00:14:16,755 --> 00:14:18,390 Almost zero traffic. 287 00:14:19,325 --> 00:14:23,028 There were no other airplanes in the area to avoid. 288 00:14:23,095 --> 00:14:25,130 It was a nice, clear day, 289 00:14:25,197 --> 00:14:27,399 so we didn't really have an explanation 290 00:14:27,466 --> 00:14:30,769 for why the airplane rolled so violently to the left. 291 00:14:32,271 --> 00:14:34,006 Narrator: Ritter won't be getting an explanation 292 00:14:34,073 --> 00:14:36,442 from any onboard flight recorders. 293 00:14:36,508 --> 00:14:37,977 At the time of the crash, 294 00:14:38,043 --> 00:14:40,813 commuter planes weren't required to carry them. 295 00:14:41,480 --> 00:14:45,784 Investigators will have to solve the mystery of flight 2311 296 00:14:45,851 --> 00:14:48,520 without one of their most useful tools. 297 00:14:48,587 --> 00:14:51,724 Ritter: Not having those made the physical evidence 298 00:14:51,790 --> 00:14:53,225 all the more important. 299 00:14:54,126 --> 00:14:55,294 What have you got for me? 300 00:14:56,495 --> 00:14:58,330 This is the third one. 301 00:14:58,397 --> 00:15:02,167 Narrator: The engines have been badly damaged in the crash. 302 00:15:02,234 --> 00:15:04,870 The propeller blades have been torn off. 303 00:15:05,971 --> 00:15:09,975 Did flight 2311 suffer some kind of engine failure? 304 00:15:10,042 --> 00:15:12,845 It's too soon to say. 305 00:15:14,613 --> 00:15:16,115 One thing Ritter does know 306 00:15:16,181 --> 00:15:18,751 is that the pressure he's feeling from the media 307 00:15:18,817 --> 00:15:20,252 is not about to let up. 308 00:15:22,021 --> 00:15:25,190 The deaths of Senator Tower and Astronaut Sonny Carter 309 00:15:25,257 --> 00:15:27,926 are sure to keep the investigation in the spotlight. 310 00:15:29,061 --> 00:15:32,431 Ritter is determined not to let the pressure get to him. 311 00:15:33,866 --> 00:15:35,534 Ritter: Sometimes we feel pressure 312 00:15:35,601 --> 00:15:37,303 to do an investigation quickly, 313 00:15:37,369 --> 00:15:41,974 but for the most part, it's more important to get it right, 314 00:15:42,041 --> 00:15:44,176 and so I would rather take the time 315 00:15:44,243 --> 00:15:46,312 and have a good analysis of the evidence 316 00:15:46,378 --> 00:15:48,747 before they come out with a probable cause. 317 00:15:49,682 --> 00:15:52,951 We won't find our answers here. 318 00:15:53,018 --> 00:15:55,187 Let's get what we can back to the hangar-- 319 00:15:55,254 --> 00:15:59,024 wings, tail, engines, instruments. 320 00:15:59,091 --> 00:16:00,793 Narrator: The question now-- 321 00:16:00,859 --> 00:16:02,761 can he find enough evidence 322 00:16:02,828 --> 00:16:05,397 to solve the mystery of flight 2311? 323 00:16:14,940 --> 00:16:17,543 Narrator: Investigators begin the painstaking task 324 00:16:17,609 --> 00:16:20,646 of sorting through the wreckage of flight 2311. 325 00:16:21,814 --> 00:16:24,717 They're searching for any evidence that might hint 326 00:16:24,783 --> 00:16:28,721 at why the Embraer 120 rolled sharply to the left and crashed, 327 00:16:28,787 --> 00:16:30,989 killing everyone on board. 328 00:16:32,391 --> 00:16:33,659 Ritter: Alright, guys. 329 00:16:33,726 --> 00:16:35,494 Let's start with the ailerons. 330 00:16:35,561 --> 00:16:36,929 Narrator: They wonder if one of the plane's 331 00:16:36,995 --> 00:16:39,798 flight control surfaces was malfunctioning. 332 00:16:41,600 --> 00:16:44,169 Maris: Control surfaces are the moveable flaps 333 00:16:44,236 --> 00:16:47,740 typically at the back of the wings, the tail, and the fin, 334 00:16:47,806 --> 00:16:50,042 which allow the pilot to roll the aircraft, 335 00:16:50,109 --> 00:16:52,411 to pitch the aircraft, and to yaw the aircraft-- 336 00:16:52,478 --> 00:16:55,581 the three motions an aircraft can do. 337 00:16:56,548 --> 00:16:58,016 Narrator: They need to examine 338 00:16:58,083 --> 00:17:00,219 every component of the flight control system. 339 00:17:01,320 --> 00:17:04,156 Ritter: What you're looking for is continuity of the controls. 340 00:17:04,223 --> 00:17:07,593 Are the hinges all intact? 341 00:17:07,659 --> 00:17:10,662 All the actuators are in their proper position? 342 00:17:10,729 --> 00:17:12,564 Were the control surfaces themselves 343 00:17:12,631 --> 00:17:15,934 in a reasonable position at the time of impact? 344 00:17:18,670 --> 00:17:20,406 Ailerons look good. 345 00:17:20,472 --> 00:17:22,241 When we examined the control surfaces, 346 00:17:22,307 --> 00:17:24,243 we didn't find anything unusual at all. 347 00:17:24,309 --> 00:17:26,712 Everything checked out normally. 348 00:17:29,615 --> 00:17:32,618 So if the control systems were all working, 349 00:17:32,684 --> 00:17:34,620 why would a plane do this? 350 00:17:35,654 --> 00:17:38,657 Left bank almost 90 degrees, 351 00:17:38,724 --> 00:17:41,427 then almost straight down. 352 00:17:45,464 --> 00:17:47,699 Maybe the engine? 353 00:17:47,766 --> 00:17:49,635 Without the black boxes, 354 00:17:49,701 --> 00:17:52,337 it's basically a process of elimination. 355 00:17:52,404 --> 00:17:54,807 We analyze all of the physical evidence 356 00:17:54,873 --> 00:17:56,742 and come up with the most compelling scenario 357 00:17:56,809 --> 00:17:59,445 that matches that evidence. 358 00:17:59,511 --> 00:18:02,080 Alright. Let's see what we can find in here. 359 00:18:03,816 --> 00:18:07,019 Narrator: If one of the plane's two turboprop engines failed, 360 00:18:07,085 --> 00:18:10,622 it might explain why the plane went into such a steep roll. 361 00:18:12,357 --> 00:18:15,093 Ritter: We wanted to look for any indications 362 00:18:15,160 --> 00:18:16,829 of an engine problem, 363 00:18:16,895 --> 00:18:19,598 so we retrieved both the left and the right engine 364 00:18:19,665 --> 00:18:20,999 and their propeller systems 365 00:18:21,066 --> 00:18:22,534 and took those back to the laboratory 366 00:18:22,601 --> 00:18:24,903 for further examination. 367 00:18:26,572 --> 00:18:30,609 Narrator: Investigators soon find some telltale evidence-- 368 00:18:30,676 --> 00:18:33,946 leaves and branches inside the engines. 369 00:18:34,813 --> 00:18:36,515 Ritter: When we find vegetation in the engines, 370 00:18:36,582 --> 00:18:38,851 that tells us that the engine is operating 371 00:18:38,917 --> 00:18:41,620 because it's sucking in air 372 00:18:41,687 --> 00:18:44,223 and it's pulling in the leaves and the vegetation, 373 00:18:44,289 --> 00:18:47,359 and that's an indication that it's making power. 374 00:18:47,426 --> 00:18:49,228 This one was spinning to the very end, 375 00:18:49,294 --> 00:18:50,829 no doubt about it. 376 00:18:51,730 --> 00:18:54,867 We confirmed that both engines were operating 377 00:18:54,933 --> 00:18:56,735 right up until the moment of impact. 378 00:18:56,802 --> 00:18:58,070 Computer: Terrain. 379 00:18:58,136 --> 00:18:59,705 Friedline: That's it. 380 00:19:01,306 --> 00:19:02,774 No! 381 00:19:08,013 --> 00:19:10,282 Narrator: With engine failure ruled out, 382 00:19:10,349 --> 00:19:12,017 Ritter turns his attention 383 00:19:12,084 --> 00:19:15,721 to the other main part of the plane's propulsion system. 384 00:19:15,787 --> 00:19:18,457 Ritter: Let's take a look at these propellers. 385 00:19:18,524 --> 00:19:19,791 Thank you. 386 00:19:20,325 --> 00:19:23,495 Narrator: Tom Haueter is an NTSB investigator. 387 00:19:23,562 --> 00:19:26,198 Haueter: When we started doing testing of the propeller system, 388 00:19:26,265 --> 00:19:28,133 we didn't know where it was gonna lead us, 389 00:19:28,200 --> 00:19:31,136 but it was something we had to eliminate, if nothing else. 390 00:19:32,771 --> 00:19:34,640 Narrator: Deep inside the propeller unit, 391 00:19:34,973 --> 00:19:38,577 investigators uncover an important clue. 392 00:19:38,644 --> 00:19:40,579 Ritter: Ah-ha! 393 00:19:40,646 --> 00:19:42,514 There you are. 394 00:19:42,581 --> 00:19:43,515 We have a witness mark. 395 00:19:43,582 --> 00:19:45,684 Take a look. 396 00:19:45,751 --> 00:19:47,185 Narrator: There's a small mark 397 00:19:47,252 --> 00:19:48,954 where two parts of the propeller mechanism 398 00:19:49,021 --> 00:19:53,058 slammed together on impact. 399 00:19:53,125 --> 00:19:56,562 The witness mark might be enough to tell investigators 400 00:19:56,628 --> 00:19:59,064 how the propellers were operating. 401 00:19:59,131 --> 00:20:03,068 Ritter: You can literally match up the scratch marks 402 00:20:03,135 --> 00:20:04,937 between both pieces, 403 00:20:05,003 --> 00:20:08,140 and you'll know what the angle of the propeller blade was 404 00:20:08,206 --> 00:20:10,142 from that measurement. 405 00:20:10,208 --> 00:20:11,910 Mark this one... 406 00:20:13,745 --> 00:20:15,881 22 degrees. 407 00:20:17,716 --> 00:20:19,585 Narrator: The Embraer 120 has what's called 408 00:20:19,651 --> 00:20:21,987 a constant speed propeller. 409 00:20:23,255 --> 00:20:26,491 The blades spin at a steady rate in flight. 410 00:20:27,159 --> 00:20:30,162 When the pilots need more power, the blades twist, 411 00:20:30,228 --> 00:20:33,298 changing their angle to take a bigger bite out of the air 412 00:20:33,365 --> 00:20:37,202 and provide more thrust. 413 00:20:37,269 --> 00:20:39,605 Friedline: Slowing for approach speed. 414 00:20:40,839 --> 00:20:42,341 Maris: And in flight, 415 00:20:42,407 --> 00:20:45,377 it acts like the automatic transmission in a car. 416 00:20:45,444 --> 00:20:47,980 It's as if it's changing gears to match the engine load, 417 00:20:48,046 --> 00:20:50,983 the speed, whether the plane is climbing or descending, 418 00:20:51,049 --> 00:20:53,051 and it does so constantly and automatically 419 00:20:53,118 --> 00:20:55,187 without intervention by the crew. 420 00:20:58,390 --> 00:21:02,260 Narrator: There are witness marks inside both propellers. 421 00:21:03,562 --> 00:21:06,565 Ritter: Now, this one... 422 00:21:06,632 --> 00:21:09,267 Looks like three degrees? 423 00:21:10,469 --> 00:21:13,238 Narrator: The marks tell Ritter the exact angle of the blades 424 00:21:13,305 --> 00:21:16,341 when the plane slammed into the ground. 425 00:21:16,408 --> 00:21:19,211 Ritter: We immediately noticed the difference 426 00:21:19,277 --> 00:21:21,213 between some of the blade angle measurements 427 00:21:21,279 --> 00:21:25,017 for the left engine versus the right engine. 428 00:21:25,083 --> 00:21:28,020 These guys had a big problem with their left propeller. 429 00:21:31,823 --> 00:21:34,660 The blades were almost flat. 430 00:21:36,094 --> 00:21:38,363 Narrator: The left side propeller blades 431 00:21:38,430 --> 00:21:40,565 are at a dangerously low angle-- 432 00:21:40,632 --> 00:21:43,802 one that is never used during flight. 433 00:21:43,869 --> 00:21:46,705 At three degrees, the blades are so flat, 434 00:21:46,772 --> 00:21:48,607 they would act like a wall, 435 00:21:48,674 --> 00:21:52,411 blocking the flow of air the plane needs to maintain lift. 436 00:21:52,477 --> 00:21:55,647 Haueter: At certain speeds and certain regimes of flight, 437 00:21:55,714 --> 00:21:57,649 if the propeller goes flat enough, 438 00:21:57,716 --> 00:22:00,819 you have a situation where you can't control the airplane. 439 00:22:05,223 --> 00:22:07,059 Narrator: Investigators study the mechanism 440 00:22:07,125 --> 00:22:10,362 used to control the left propeller. 441 00:22:10,429 --> 00:22:12,197 Ritter: Will you look at this? 442 00:22:14,132 --> 00:22:16,234 Narrator: They make a disturbing discovery. 443 00:22:16,301 --> 00:22:18,270 Ritter: It's completely worn down. 444 00:22:18,336 --> 00:22:20,772 Narrator: The teeth on a key piece of the gear mechanism, 445 00:22:20,839 --> 00:22:22,674 known as the quill, 446 00:22:22,741 --> 00:22:25,911 are almost entirely worn away. 447 00:22:25,977 --> 00:22:28,080 Investigators may finally have the lead 448 00:22:28,146 --> 00:22:29,948 they've been looking for. 449 00:22:30,015 --> 00:22:31,883 Ritter: This is what it's supposed to look like. 450 00:22:35,287 --> 00:22:37,255 Narrator: With its teeth worn away, 451 00:22:37,322 --> 00:22:39,324 the quill can't lock onto the gear system 452 00:22:39,391 --> 00:22:42,661 that controls the angle of the propeller blades. 453 00:22:43,628 --> 00:22:46,732 The discovery might explain why the propeller blades 454 00:22:46,798 --> 00:22:50,001 slipped to such a dangerously low angle. 455 00:22:52,170 --> 00:22:56,007 Ritter: Once we noticed that the quill teeth were severely worn, 456 00:22:56,074 --> 00:22:58,977 we started theorizing what would happen 457 00:22:59,044 --> 00:23:01,446 in that type of situation, 458 00:23:01,513 --> 00:23:03,181 and it was pretty clear that 459 00:23:03,248 --> 00:23:07,352 control of the propeller blade angles could be lost. 460 00:23:07,819 --> 00:23:10,021 And that really was a eureka moment for us, 461 00:23:10,088 --> 00:23:13,325 because now we had a serious malfunction 462 00:23:13,391 --> 00:23:16,094 that we could examine. 463 00:23:16,962 --> 00:23:18,830 Ritter: This could 464 00:23:16,962 --> 00:23:18,830 definitely be it. 465 00:23:20,065 --> 00:23:22,167 Narrator: Ritter digs into manufacturing reports, 466 00:23:22,234 --> 00:23:26,438 trying to find out how such a vital part could have failed. 467 00:23:26,505 --> 00:23:29,908 But what he finds only adds to the mystery. 468 00:23:30,742 --> 00:23:32,110 The quill teeth are made 469 00:23:32,177 --> 00:23:35,413 of an extremely durable case-hardened metal. 470 00:23:35,480 --> 00:23:37,949 Ritter: They were definitely made to last. 471 00:23:38,016 --> 00:23:40,018 Narrator: It's hard to imagine what could have caused 472 00:23:40,085 --> 00:23:43,755 such rugged teeth to wear down so badly. 473 00:23:43,822 --> 00:23:45,557 Ritter: Something didn't work as planned. 474 00:23:45,624 --> 00:23:48,693 Let's find out everything we can about every one of these pieces. 475 00:23:49,528 --> 00:23:52,430 Narrator: Ritter is certain he's found the critical clue-- 476 00:23:52,497 --> 00:23:55,534 worn-down teeth on the quill that could have allowed 477 00:23:55,600 --> 00:23:59,304 the propeller blades to slip to a dangerous angle. 478 00:24:00,138 --> 00:24:04,009 But he soon learns there's a big problem with his theory. 479 00:24:04,910 --> 00:24:07,612 The manufacturer says it's impossible. 480 00:24:08,513 --> 00:24:11,983 Engineers at Hamilton Standard included a fail-safe feature 481 00:24:12,050 --> 00:24:14,119 when they designed the propeller. 482 00:24:14,186 --> 00:24:18,790 It should be impossible for the blades to go flat during flight. 483 00:24:20,058 --> 00:24:22,327 Maris: Manufacturers have to demonstrate, 484 00:24:22,394 --> 00:24:25,897 through a number of means, that their systems are fail-safe. 485 00:24:27,098 --> 00:24:28,300 Haueter: All the tests and research 486 00:24:28,366 --> 00:24:29,835 that had been done before this said 487 00:24:29,901 --> 00:24:32,270 even if you have a disconnect, 488 00:24:32,337 --> 00:24:34,873 that will not result in an accident. 489 00:24:36,975 --> 00:24:38,443 Narrator: If there's ever a problem 490 00:24:38,510 --> 00:24:40,278 with the mechanism controlling the angle, 491 00:24:40,345 --> 00:24:42,380 the blades are designed to move on their own 492 00:24:42,447 --> 00:24:45,383 to what's called the feathered position. 493 00:24:46,918 --> 00:24:48,553 Haueter: The feathered propeller blade, 494 00:24:48,620 --> 00:24:52,224 the leading edge of the blade is directly into the wind, 495 00:24:52,290 --> 00:24:54,226 so that's the most minimal drag, 496 00:24:54,292 --> 00:24:56,895 no thrust, but very little drag. 497 00:24:56,962 --> 00:24:58,563 Narrator: A feathered propeller 498 00:24:58,630 --> 00:25:01,666 can't endanger the safety of the flight. 499 00:25:01,733 --> 00:25:04,502 Maris: If this rod disengaged because of any cause, 500 00:25:04,569 --> 00:25:06,204 the propeller should go to feather, 501 00:25:06,271 --> 00:25:08,406 which would result in the loss of the engine, 502 00:25:08,473 --> 00:25:10,175 and the crew would be able to cope with that 503 00:25:10,242 --> 00:25:13,245 and land on one engine, as they are trained to do. 504 00:25:13,311 --> 00:25:15,413 Friedline: The runway's in sight. 505 00:25:18,283 --> 00:25:20,285 Ritter: This has got to be it. 506 00:25:21,419 --> 00:25:24,289 This has to be connected somehow. 507 00:25:24,789 --> 00:25:26,124 Narrator: But Ritter isn't convinced 508 00:25:26,191 --> 00:25:28,660 by the manufacturer's assurances. 509 00:25:28,727 --> 00:25:32,731 His gut tells him the worn quill did allow the propeller blades 510 00:25:32,797 --> 00:25:34,933 to move to a dangerous angle. 511 00:25:36,234 --> 00:25:37,969 But without flight data, 512 00:25:38,036 --> 00:25:40,505 his investigation has hit a wall. 513 00:25:40,572 --> 00:25:44,576 He has no way to prove the quill brought down flight 2311. 514 00:25:45,777 --> 00:25:47,479 Friedline: What's going on? 515 00:25:47,545 --> 00:25:49,080 Can you see anything? 516 00:25:49,147 --> 00:25:50,949 Johnston: There's nothing. 517 00:25:59,624 --> 00:26:01,893 Ritter: Tom, welcome to the team. 518 00:26:01,960 --> 00:26:04,062 Haueter: No problem, Jim. Glad to help. 519 00:26:04,129 --> 00:26:06,798 Narrator: With the investigation stalled, 520 00:26:06,865 --> 00:26:09,868 Tom Haueter joins Jim Ritter to hunt for answers 521 00:26:09,935 --> 00:26:13,371 in the crash of Atlantic Southeast flight 2311. 522 00:26:14,940 --> 00:26:16,741 Haueter: I was a little nervous about this one 523 00:26:16,808 --> 00:26:18,910 in that when I first jumped into it, 524 00:26:18,977 --> 00:26:21,780 I didn't really know what was going on 525 00:26:21,846 --> 00:26:24,716 other than it was basically at a standstill 526 00:26:24,783 --> 00:26:27,085 and they were looking for me to get it moving. 527 00:26:27,152 --> 00:26:28,520 What do we have? 528 00:26:28,586 --> 00:26:29,621 Ritter: I think everything we need to know 529 00:26:29,688 --> 00:26:31,756 is right here on this table. 530 00:26:32,290 --> 00:26:35,727 Haueter: You have a part of the propeller control assembly, 531 00:26:35,794 --> 00:26:38,630 and the teeth on the gear are essentially gone. 532 00:26:38,697 --> 00:26:41,032 That's very unusual. 533 00:26:41,099 --> 00:26:43,234 Could that have been a part of the accident? 534 00:26:43,301 --> 00:26:44,703 We didn't know. 535 00:26:46,137 --> 00:26:48,106 Narrator: Haueter and Ritter study the design 536 00:26:48,173 --> 00:26:51,142 of the propeller mechanism. 537 00:26:51,209 --> 00:26:53,011 Ritter: Tom, look at this. 538 00:26:53,078 --> 00:26:56,047 Haueter: We don't see anything obviously wrong with the crew. 539 00:26:56,114 --> 00:26:58,817 We don't see anything wrong with the structure of the aircraft. 540 00:26:58,883 --> 00:27:00,585 We don't see anything wrong with the engines 541 00:27:00,652 --> 00:27:02,087 and the flight control system, 542 00:27:02,153 --> 00:27:05,223 but we do have a severely worn Transfer Tube 543 00:27:05,290 --> 00:27:06,925 and quill arrangement. 544 00:27:07,659 --> 00:27:11,429 Is it possible that this could have resulted 545 00:27:11,496 --> 00:27:13,465 in the loss of control? 546 00:27:13,531 --> 00:27:16,334 Narrator: They discover that shortly before the accident, 547 00:27:16,401 --> 00:27:19,971 Hamilton Standard started using a harder, more abrasive coating 548 00:27:20,038 --> 00:27:23,074 on a key part known as the Transfer Tube. 549 00:27:24,275 --> 00:27:28,780 Its grooves mesh-like clockwork into the teeth of the quill. 550 00:27:28,847 --> 00:27:32,584 The change had an unexpected consequence. 551 00:27:32,650 --> 00:27:34,452 Haueter: It turned it into a giant file. 552 00:27:35,754 --> 00:27:38,056 Ritter: So the splines on the Transfer Tube 553 00:27:38,123 --> 00:27:41,493 were much harder and rougher than the quill teeth, 554 00:27:41,559 --> 00:27:43,228 and it was almost like sandpaper, 555 00:27:43,294 --> 00:27:44,596 so the tube was actually 556 00:27:44,662 --> 00:27:46,731 wearing down the teeth on the quill. 557 00:27:47,799 --> 00:27:51,202 Narrator: The discovery explains the worn teeth on the quill. 558 00:27:54,639 --> 00:27:57,208 The design of the propeller should ensure 559 00:27:57,275 --> 00:27:59,611 it snaps to a safe position, 560 00:27:59,677 --> 00:28:01,579 even with the worn part. 561 00:28:02,914 --> 00:28:06,051 Ritter: The propeller manufacturer believed 562 00:28:06,117 --> 00:28:08,386 that they had a fail-safe condition, 563 00:28:08,453 --> 00:28:10,188 so that even if they had this problem, 564 00:28:10,255 --> 00:28:13,191 the propeller blades would be slowly driven 565 00:28:13,258 --> 00:28:14,926 to the feather position. 566 00:28:16,928 --> 00:28:19,164 Narrator: In spite of what all their data says, 567 00:28:19,230 --> 00:28:22,200 the investigators want to see for themselves. 568 00:28:26,805 --> 00:28:29,808 They set up a test at the manufacturer's facility. 569 00:28:32,077 --> 00:28:35,513 Ritter: We had an engine and a propeller combination 570 00:28:35,580 --> 00:28:37,582 mounted in a test cell. 571 00:28:39,918 --> 00:28:42,320 Maris: In order to determine that something is fail-safe, 572 00:28:42,387 --> 00:28:45,457 the engineers use a combination of mathematical analysis, 573 00:28:45,523 --> 00:28:47,258 very structured analysis, 574 00:28:47,325 --> 00:28:50,261 testing in a laboratory, as you can imagine, 575 00:28:50,328 --> 00:28:51,663 and by these methods, 576 00:28:51,729 --> 00:28:53,331 Hamilton Standard convinced themselves 577 00:28:53,398 --> 00:28:56,434 that this propeller would fail in a safe direction, 578 00:28:56,501 --> 00:28:57,902 i.e., towards feather. 579 00:29:03,942 --> 00:29:06,978 Narrator: Jim Ritter's doubts about the fail-safe design 580 00:29:07,045 --> 00:29:10,115 may be confirmed in just a few seconds. 581 00:29:12,183 --> 00:29:14,752 The technician flips a switch to free the Transfer Tube 582 00:29:14,819 --> 00:29:16,754 from the teeth on the quill. 583 00:29:19,390 --> 00:29:23,328 But as the test unfolds, instead of moving to flat, 584 00:29:23,394 --> 00:29:26,397 the propeller blades move to the safe feathered position. 585 00:29:27,298 --> 00:29:31,169 The fail-safe system performs exactly as it was designed to. 586 00:29:34,272 --> 00:29:36,241 It suddenly seems that investigators 587 00:29:36,307 --> 00:29:38,877 are on the wrong path altogether. 588 00:29:40,411 --> 00:29:43,715 Ritter: So, when we tested the quill with the worn teeth 589 00:29:43,781 --> 00:29:46,317 at the manufacturer's facility, 590 00:29:46,384 --> 00:29:49,254 we found that the propeller blades went to feather, 591 00:29:49,320 --> 00:29:53,758 so at that point, we were basically stumped. 592 00:29:53,825 --> 00:29:55,293 Haueter: Can you play it again? 593 00:29:58,530 --> 00:30:02,133 Narrator: The test results leave Ritter and Haueter wondering, 594 00:30:02,200 --> 00:30:05,203 could there be some other factor that they've overlooked? 595 00:30:06,905 --> 00:30:08,606 Haueter: Hold on. 596 00:30:09,274 --> 00:30:10,842 That's it. 597 00:30:10,909 --> 00:30:13,344 It's bolted to the ground. 598 00:30:13,411 --> 00:30:14,913 The question I raised, 599 00:30:14,979 --> 00:30:17,916 well, in flight, the aircraft is in turbulence, 600 00:30:17,982 --> 00:30:19,350 it's bouncing around. 601 00:30:19,417 --> 00:30:21,052 There's different vibrations. 602 00:30:21,119 --> 00:30:22,754 With the aircraft on the ground 603 00:30:22,820 --> 00:30:25,123 or an engine mounted solidly to the ground, 604 00:30:25,190 --> 00:30:26,824 the airplane doesn't behave the same. 605 00:30:26,891 --> 00:30:29,160 There's different vibration modes. 606 00:30:29,227 --> 00:30:33,464 Is it possible that could change the outcome of the analysis? 607 00:30:34,032 --> 00:30:35,700 Haueter: I think we need to see it in the air. 608 00:30:35,767 --> 00:30:38,269 Ritter: Definitely. 609 00:30:38,336 --> 00:30:40,572 Maris: One of the problems with doing testing 610 00:30:40,638 --> 00:30:43,308 in a laboratory environment, which is very controlled, 611 00:30:43,374 --> 00:30:45,677 is that you can't always anticipate what will happen 612 00:30:45,743 --> 00:30:48,179 when you go out into the real world. 613 00:30:51,449 --> 00:30:54,185 Carter: These small planes do keep you on your toes. 614 00:30:54,252 --> 00:30:57,355 Maris: Imagine, for example, an orchestra that rehearses 615 00:30:57,422 --> 00:31:00,258 in an acoustically perfect concert hall 616 00:31:00,325 --> 00:31:04,362 and then performs outside with random noises, 617 00:31:04,429 --> 00:31:06,164 without the sound controlled. 618 00:31:06,231 --> 00:31:09,701 You can see how one might miss important factors 619 00:31:09,767 --> 00:31:11,302 about the sound. 620 00:31:11,369 --> 00:31:14,172 Haueter: We've got to see what happens in the air. 621 00:31:14,239 --> 00:31:17,008 I said, "Well, the only way to really know 622 00:31:17,075 --> 00:31:19,010 is let's do a flight test and find out." 623 00:31:19,077 --> 00:31:22,547 Let's do something to absolutely determine this is the case, 624 00:31:22,614 --> 00:31:24,682 'cause we were at a point in the investigation 625 00:31:24,749 --> 00:31:27,385 we need to start eliminating things. 626 00:31:33,291 --> 00:31:37,161 Narrator: The investigation into the crash of flight 2311 627 00:31:37,228 --> 00:31:39,764 moves to Embraer headquarters in Brazil. 628 00:31:41,065 --> 00:31:42,567 Ritter: We really wanted to look at 629 00:31:42,634 --> 00:31:45,903 what would happen in flight, in an actual flight 630 00:31:45,970 --> 00:31:47,372 with the same malfunction? 631 00:31:49,274 --> 00:31:52,410 Narrator: Tom Haueter meets with representatives from Embraer 632 00:31:52,477 --> 00:31:54,846 and propeller manufacturer Hamilton Standard. 633 00:31:56,080 --> 00:31:59,617 The team immediately starts preparing for the test flight. 634 00:32:00,118 --> 00:32:02,553 Haueter: Thank you for doing this. 635 00:32:02,620 --> 00:32:05,256 When I first proposed doing the flight test, 636 00:32:05,323 --> 00:32:08,760 it was not well-received by almost everybody. 637 00:32:08,826 --> 00:32:10,828 People saw no need. 638 00:32:10,895 --> 00:32:12,597 Why are we spending the time, the money? 639 00:32:12,664 --> 00:32:14,232 Why are we doing this? 640 00:32:14,732 --> 00:32:16,334 Would you mind if I used that table? 641 00:32:16,401 --> 00:32:17,568 Is that okay? 642 00:32:17,635 --> 00:32:19,237 But I pushed hard. 643 00:32:19,304 --> 00:32:22,674 I thought, "Well, we need to really prove this." 644 00:32:22,740 --> 00:32:25,977 Narrator: Embraer's chief test pilot, Gilberto Schittini, 645 00:32:26,044 --> 00:32:27,612 has agreed to put the investigators' theory 646 00:32:27,679 --> 00:32:29,213 to the test. 647 00:32:30,315 --> 00:32:34,085 Gilberto Schittini: The risks, of course, is part of the game, 648 00:32:34,152 --> 00:32:36,587 so you have, always have to reduce your risk 649 00:32:36,654 --> 00:32:38,056 as much as possible, 650 00:32:38,122 --> 00:32:41,225 but you cannot avoid it, so you just accept it. 651 00:32:43,261 --> 00:32:46,464 Maris: The mindset of a test pilot is one 652 00:32:46,531 --> 00:32:48,333 not perhaps of heroic bravery, 653 00:32:48,399 --> 00:32:51,936 but certainly one wants to be unflappable 654 00:32:52,003 --> 00:32:55,640 in the face of danger and unusual situations, 655 00:32:55,707 --> 00:32:58,142 because you're not very productive 656 00:32:58,209 --> 00:33:01,546 if you're terrified by the goings-on in the cockpit. 657 00:33:03,348 --> 00:33:05,983 Narrator: Schittini will fly an Embraer 120 658 00:33:06,050 --> 00:33:09,487 that has been modified to recreate the failure 659 00:33:09,554 --> 00:33:11,756 on flight 2311. 660 00:33:11,823 --> 00:33:13,725 Haueter: So, we've modified the quill. 661 00:33:13,791 --> 00:33:17,095 The teeth have been worn down just like flight 2311. 662 00:33:18,296 --> 00:33:19,931 Narrator: A worn quill will be placed 663 00:33:19,997 --> 00:33:23,234 inside the propeller unit. 664 00:33:23,301 --> 00:33:25,703 Haueter: This was potentially very high risk, 665 00:33:25,770 --> 00:33:29,140 because once we disconnected the Transfer Tube in flight, 666 00:33:29,207 --> 00:33:31,476 the pilots would have no way to control the propeller. 667 00:33:32,510 --> 00:33:34,979 We put a pitch lock here. 668 00:33:35,046 --> 00:33:36,748 It won't go past 22 degrees. 669 00:33:37,749 --> 00:33:39,984 Narrator: A mechanical lock has also been added 670 00:33:40,051 --> 00:33:43,855 to stop the propeller from going flatter than 22 degrees. 671 00:33:44,756 --> 00:33:47,191 Haueter: It would be too dangerous in the flight test 672 00:33:47,258 --> 00:33:50,161 to have the propeller blade go all the way to flat pitch. 673 00:33:50,228 --> 00:33:51,662 You'd lose control of the airplane. 674 00:33:51,729 --> 00:33:53,798 That was almost guaranteed. 675 00:33:53,865 --> 00:33:56,100 If the blades move to 22 degrees, 676 00:33:56,167 --> 00:33:58,302 then we know that they would have gone flat. 677 00:33:58,369 --> 00:33:59,871 All good? 678 00:33:59,937 --> 00:34:03,141 Narrator: The propeller blades don't need to go completely flat 679 00:34:03,207 --> 00:34:05,810 to prove that Haueter's on the right track. 680 00:34:05,877 --> 00:34:08,713 Schittini: This was a high-risk test. 681 00:34:08,780 --> 00:34:11,783 We had to take extra precautions 682 00:34:11,849 --> 00:34:14,585 in order not to repeat the accident. 683 00:34:15,820 --> 00:34:18,623 Narrator: Real-time data will tell the team on the ground 684 00:34:18,689 --> 00:34:21,726 whether the propeller blades are going safely towards feather 685 00:34:21,793 --> 00:34:24,395 or moving dangerously flat. 686 00:34:24,462 --> 00:34:27,031 Haueter: Everything says that if you have a disconnect, 687 00:34:27,098 --> 00:34:29,834 the normal frictional drag within the system 688 00:34:29,901 --> 00:34:31,969 will cause the components to rotate 689 00:34:32,036 --> 00:34:34,372 towards the feather position, 690 00:34:34,439 --> 00:34:37,575 but will that really happen in flight the same way? 691 00:34:40,111 --> 00:34:42,447 Narrator: They're about to find out. 692 00:34:43,214 --> 00:34:45,783 Haueter: We were comfortable that this test 693 00:34:45,850 --> 00:34:47,752 could be safely accomplished, 694 00:34:47,819 --> 00:34:49,353 but there's a difference 695 00:34:49,420 --> 00:34:51,355 between believing it can be safely accomplished 696 00:34:51,422 --> 00:34:52,890 and knowing. 697 00:34:55,193 --> 00:34:57,261 Narrator: As the test plane climbs, 698 00:34:57,328 --> 00:34:59,864 Schittini takes it over an unpopulated area, 699 00:34:59,931 --> 00:35:01,399 just in case. 700 00:35:02,700 --> 00:35:04,068 Haueter: There was a potential 701 00:35:04,135 --> 00:35:07,705 for a severe controllability problem 702 00:35:07,772 --> 00:35:10,341 such that the pilots might have to abandon the aircraft 703 00:35:10,408 --> 00:35:12,243 and parachute to the ground. 704 00:35:13,578 --> 00:35:15,313 Narrator: The propellers have been set 705 00:35:15,379 --> 00:35:17,482 to a normal angle for flight-- 706 00:35:17,548 --> 00:35:19,217 around 30 degrees. 707 00:35:20,184 --> 00:35:22,353 Haueter: EMB-120, do you copy? 708 00:35:22,420 --> 00:35:25,256 There was a lot on the line, in terms of the fact 709 00:35:25,323 --> 00:35:27,225 that what if this airplane crashes? 710 00:35:27,792 --> 00:35:29,427 What if we lose the airplane? 711 00:35:30,394 --> 00:35:32,897 Certainly I'm the investigator in charge. 712 00:35:32,964 --> 00:35:35,500 I'm the one, you know, who's basically running this test. 713 00:35:35,566 --> 00:35:38,369 This could be all my responsibility. 714 00:35:38,436 --> 00:35:39,570 Schittini: Copy. 715 00:35:39,637 --> 00:35:42,006 We are ready to disengage the prop. 716 00:35:43,341 --> 00:35:45,676 Haueter: Basically they would pull the lever 717 00:35:45,743 --> 00:35:48,980 that would disconnect the propeller control system 718 00:35:49,046 --> 00:35:50,648 from the propeller 719 00:35:50,715 --> 00:35:52,450 and see what happens. 720 00:35:54,519 --> 00:35:56,587 Narrator: The most dangerous part of the test flight 721 00:35:56,654 --> 00:35:58,422 is now under way. 722 00:35:59,957 --> 00:36:03,794 Schittini: I just thought that, well, it's happening. 723 00:36:03,861 --> 00:36:07,498 Let's do what we have to do and get this airplane on the ground. 724 00:36:07,999 --> 00:36:11,469 Maris: This was, in my opinion a very dangerous maneuver, 725 00:36:11,536 --> 00:36:12,837 because after all, they didn't know 726 00:36:12,904 --> 00:36:14,438 what the outcome was going to be, 727 00:36:14,505 --> 00:36:16,674 and they already knew the aircraft wasn't controllable 728 00:36:16,741 --> 00:36:18,809 under certain circumstances. 729 00:36:18,876 --> 00:36:21,979 Schittini: Propeller blade angle is causing no problems. 730 00:36:22,046 --> 00:36:24,181 No control issues. 731 00:36:24,982 --> 00:36:28,953 We were thinking about the test to do and nothing else. 732 00:36:29,020 --> 00:36:33,224 You have to focus on the job that you have to do ahead, 733 00:36:33,291 --> 00:36:36,761 and once you focus you forget about everything else. 734 00:36:38,429 --> 00:36:41,232 Narrator: As soon as the propeller quill is disengaged, 735 00:36:41,299 --> 00:36:44,368 the blades begin doing what they were designed to do-- 736 00:36:44,435 --> 00:36:46,737 moving towards the feathered position. 737 00:36:47,805 --> 00:36:50,508 Haueter: As it starts drifting towards feather, 738 00:36:50,575 --> 00:36:51,609 we thought, "Okay. 739 00:36:51,676 --> 00:36:53,444 Well, this test is gonna be a bust. 740 00:36:53,511 --> 00:36:55,479 It's just gonna prove what everybody said it would do." 741 00:36:56,781 --> 00:36:57,782 You could see it in their faces. 742 00:36:57,848 --> 00:36:59,483 They didn't say anything, 743 00:36:59,550 --> 00:37:02,453 but you could just, you know, hear the relief. 744 00:37:02,520 --> 00:37:04,288 Narrator: The propeller blades keep moving 745 00:37:04,355 --> 00:37:06,991 toward the fail-safe position. 746 00:37:07,425 --> 00:37:11,429 For Tom Haueter, Brazil is a long way to come for failure. 747 00:37:13,064 --> 00:37:14,799 It seems like the test 748 00:37:14,865 --> 00:37:18,135 that he hoped would solve the mystery of flight 2311 749 00:37:18,202 --> 00:37:19,971 is going to leave the investigation 750 00:37:20,037 --> 00:37:21,806 back at square one. 751 00:37:29,847 --> 00:37:32,450 Narrator: With the cause of the Atlantic Southeast crash 752 00:37:32,516 --> 00:37:33,884 still unknown 753 00:37:33,951 --> 00:37:36,320 and the entire investigation on the line, 754 00:37:36,387 --> 00:37:39,423 the Brazilian test flight takes a dramatic turn. 755 00:37:40,491 --> 00:37:44,195 Schittini: We saw that the RPM was increasing slowly, 756 00:37:44,261 --> 00:37:46,697 but it was increasing, so we knew that the propeller 757 00:37:46,764 --> 00:37:49,734 was going in the wrong direction. 758 00:37:52,603 --> 00:37:54,305 Narrator: As the flight continues, 759 00:37:54,372 --> 00:37:57,308 the blades begin drifting in the opposite direction, 760 00:37:57,375 --> 00:38:00,211 towards the dangerous flat position. 761 00:38:03,614 --> 00:38:05,116 Haueter: Ah-ha. 762 00:38:06,417 --> 00:38:07,752 Here we go. 763 00:38:09,987 --> 00:38:12,356 Ritter: The aerodynamics, the vibration, 764 00:38:12,423 --> 00:38:15,926 the actual in-flight loads on the propeller 765 00:38:15,993 --> 00:38:19,296 are something that you just can't predict in a test. 766 00:38:19,363 --> 00:38:22,033 It's something that actually had to be flown. 767 00:38:24,001 --> 00:38:26,203 Narrator: Schittini remains smooth and precise 768 00:38:26,270 --> 00:38:28,372 on the controls. 769 00:38:28,439 --> 00:38:30,141 Schittini: Reducing speed. 770 00:38:31,475 --> 00:38:34,178 Easy does it. 771 00:38:37,148 --> 00:38:40,384 We started feeling a rolling moment to the left 772 00:38:40,451 --> 00:38:43,287 and a yaw moment to the left. 773 00:38:44,422 --> 00:38:48,159 Narrator: The blades go as flat as this test will allow, 774 00:38:48,225 --> 00:38:50,061 22 degrees. 775 00:38:50,127 --> 00:38:53,197 For Haueter, it's a victory. 776 00:38:53,264 --> 00:38:55,866 The risky test flight has paid off. 777 00:38:55,933 --> 00:38:59,003 His theory about the crash is back on solid ground. 778 00:38:59,070 --> 00:39:02,173 Haueter: The Hamilton Standard and the FA people 779 00:39:02,239 --> 00:39:03,407 just went white. 780 00:39:03,474 --> 00:39:04,875 I mean, they were just shocked. 781 00:39:04,942 --> 00:39:06,210 You could tell that everything they believed 782 00:39:06,277 --> 00:39:08,913 had just been thrown out the window. 783 00:39:10,715 --> 00:39:12,783 That's as flat as they're gonna get. 784 00:39:15,052 --> 00:39:17,521 Schittini: Do you have what you need? 785 00:39:17,588 --> 00:39:18,823 Haueter: Affirmative. 786 00:39:18,889 --> 00:39:20,458 We have everything we need. 787 00:39:22,693 --> 00:39:25,463 Schittini: Okay, we're going back. 788 00:39:30,201 --> 00:39:33,304 Once the test part is finished, it is finished. 789 00:39:33,370 --> 00:39:35,673 Don't stay around looking for trouble. 790 00:39:35,740 --> 00:39:37,208 Go back home. 791 00:39:38,743 --> 00:39:39,844 Haueter: Good work. 792 00:39:39,910 --> 00:39:41,412 Thanks very much. 793 00:39:41,479 --> 00:39:43,013 Seeing the data right then, it took a load off. 794 00:39:43,080 --> 00:39:44,815 I said, "Okay, wow." 795 00:39:44,882 --> 00:39:46,917 I mean, we now know what happened. 796 00:39:46,984 --> 00:39:49,019 It was obvious. 797 00:39:49,086 --> 00:39:51,388 Looks like you have some work to do. 798 00:39:58,562 --> 00:39:59,864 Ritter: Hello. 799 00:40:00,831 --> 00:40:03,267 Narrator: The team has just one more question to answer 800 00:40:03,334 --> 00:40:05,803 before they can explain the crash. 801 00:40:06,470 --> 00:40:10,207 What happens when blades go completely flat? 802 00:40:10,274 --> 00:40:11,675 Ritter: In the flight test, 803 00:40:11,742 --> 00:40:13,110 they were only able to go 804 00:40:13,177 --> 00:40:15,513 to a blade angle of about 22 degrees 805 00:40:15,579 --> 00:40:16,914 for safety reasons. 806 00:40:16,981 --> 00:40:18,682 Start it. 807 00:40:18,749 --> 00:40:21,385 But during my flight simulations, 808 00:40:21,452 --> 00:40:25,422 I went down to flight angles as low as three degrees. 809 00:40:25,489 --> 00:40:28,058 Anytime. 810 00:40:28,626 --> 00:40:30,261 Narrator: In a flight simulator, 811 00:40:30,327 --> 00:40:33,063 Jim Ritter recreates the fatal propeller malfunction 812 00:40:33,130 --> 00:40:38,169 aboard Atlantic Southeast Airlines flight 2311. 813 00:40:38,235 --> 00:40:42,072 Ritter: As the blade angle got to very low values, 814 00:40:42,139 --> 00:40:45,276 the airplane was essentially uncontrollable. 815 00:40:46,977 --> 00:40:49,079 Narrator: The simulation allows him to experience 816 00:40:49,146 --> 00:40:51,248 what the test pilot couldn't. 817 00:40:53,684 --> 00:40:55,052 Haueter: Flight tests proved 818 00:40:55,119 --> 00:40:57,021 we could have a blade go to flat pitch. 819 00:40:57,087 --> 00:40:59,423 The simulator proved you'd lose control if it did. 820 00:41:00,090 --> 00:41:01,458 Ritter: Thanks. 821 00:41:01,525 --> 00:41:03,828 That was... helpful. 822 00:41:03,894 --> 00:41:06,230 You could say that the simulator testing 823 00:41:06,297 --> 00:41:09,600 was kind of like the final piece of the puzzle. 824 00:41:11,669 --> 00:41:14,405 Narrator: Investigators finally understand the full story 825 00:41:14,471 --> 00:41:16,841 behind the deadly crash. 826 00:41:17,741 --> 00:41:20,344 Ritter: When the flight crew began preparations for landing, 827 00:41:20,411 --> 00:41:22,847 the teeth on the quill were worn down, 828 00:41:22,913 --> 00:41:25,149 but still operational. 829 00:41:25,216 --> 00:41:27,318 Friedline: Slowing for approach speed. 830 00:41:28,385 --> 00:41:30,888 Narrator: Preparing for landing put renewed pressure 831 00:41:30,955 --> 00:41:33,757 on the already worn teeth in the quill. 832 00:41:33,824 --> 00:41:36,126 They could no longer hold. 833 00:41:37,228 --> 00:41:38,929 Once the teeth gave way, 834 00:41:39,496 --> 00:41:43,200 the propeller blades were free to drift to a different angle. 835 00:41:44,935 --> 00:41:46,270 As the turbulence of flight 836 00:41:46,337 --> 00:41:48,839 and mechanical vibrations from the engine 837 00:41:48,906 --> 00:41:50,674 shook the propeller, 838 00:41:50,741 --> 00:41:54,044 the blades moved to a dangerously flat position. 839 00:41:56,380 --> 00:41:59,884 Ritter: The fail-safe failed. 840 00:42:00,618 --> 00:42:04,255 The propeller's design couldn't hold the blades at a safe angle, 841 00:42:04,321 --> 00:42:06,423 and the plane became less and less controllable. 842 00:42:09,627 --> 00:42:12,029 Friedline: What's going on? 843 00:42:12,096 --> 00:42:13,397 You see anything? 844 00:42:14,298 --> 00:42:16,433 Johnston: There's nothing. 845 00:42:16,500 --> 00:42:17,668 Friedline: What's going on with this thing? 846 00:42:17,735 --> 00:42:19,436 I can't hold it. 847 00:42:23,007 --> 00:42:24,341 Johnston: Get out of it! 848 00:42:24,408 --> 00:42:26,176 Friedline: I can't. Come on. Come on! 849 00:42:26,243 --> 00:42:28,746 Haueter: For a while, you can kind of fight this, 850 00:42:28,812 --> 00:42:32,016 putting in control movements with the wheels, the rudder, 851 00:42:32,082 --> 00:42:34,885 but, unfortunately, they were in a situation 852 00:42:34,952 --> 00:42:36,453 where it didn't matter 853 00:42:36,520 --> 00:42:38,622 if you were the best pilot on the planet. 854 00:42:38,689 --> 00:42:40,557 You were not going to be able to control that airplane. 855 00:42:40,624 --> 00:42:42,059 It's going to roll over. 856 00:42:42,126 --> 00:42:44,028 It's gonna dive towards the ground. 857 00:42:45,763 --> 00:42:49,333 Maris: Ironically, human error is almost always underneath 858 00:42:49,400 --> 00:42:51,435 the causes of an accident, 859 00:42:51,502 --> 00:42:54,338 even if it wasn't the pilot or a mechanic. 860 00:42:54,405 --> 00:42:57,174 In this particular case, an engineering change was made, 861 00:42:57,241 --> 00:43:00,411 which, well-intentioned, actually, did not work out. 862 00:43:00,477 --> 00:43:01,512 Johnston: No! 863 00:43:01,578 --> 00:43:03,113 Friedline: That's it. Oh, God! 864 00:43:04,782 --> 00:43:06,550 Johnston: No. 865 00:43:10,387 --> 00:43:11,889 Haueter: The worn quill teeth 866 00:43:11,956 --> 00:43:13,424 was a time bomb waiting to go off. 867 00:43:15,592 --> 00:43:19,296 There was nothing they could have done to save that plane. 868 00:43:19,363 --> 00:43:22,166 What I really felt was, "Okay, now that we know it, 869 00:43:22,232 --> 00:43:24,268 we've got to tell the rest of the world 870 00:43:24,335 --> 00:43:26,236 and get operators to start changing their equipment, 871 00:43:26,303 --> 00:43:28,238 like, right now." 872 00:43:28,305 --> 00:43:30,341 The fail-safe system doesn't work. 873 00:43:31,008 --> 00:43:34,244 Narrator: After the accident, additional safeguards were added 874 00:43:34,311 --> 00:43:37,181 to prevent this type of failure-- 875 00:43:37,247 --> 00:43:39,583 a change that affected not only the Embraer, 876 00:43:39,650 --> 00:43:43,087 but several other turboprop aircraft as well. 877 00:43:43,153 --> 00:43:46,924 The FAA also ordered more frequent inspections 878 00:43:46,991 --> 00:43:48,525 of propeller quills. 879 00:43:48,592 --> 00:43:50,427 Haueter: The most important thing we have learned 880 00:43:50,494 --> 00:43:53,163 from the accident at Brunswick 881 00:43:53,230 --> 00:43:55,432 is assumptions. 882 00:43:55,499 --> 00:43:57,401 You cannot rely on assumptions. 883 00:43:57,468 --> 00:44:00,704 It was assumed that ground tests were as good as flight tests. 884 00:44:00,771 --> 00:44:03,307 That one assumption unfortunately turned out 885 00:44:03,374 --> 00:44:05,342 to be fatal for some people.