ALASKA_AIRLINES_DISPATCH AUTOMATION BILL_ADAIR BOB_SWAIM BRIAN_BISHOP CAPTAIN_AGUIAR CAPTAIN_GERMANO CAPTAIN_GREEN CAPTAIN_THOMPSON CHARLEY_PEREIRA CONTROLLER FIRST_OFFICER_EIDSON FIRST_OFFICER_EMMETT FIRST_OFFICER_GAGLIANO FIRST_OFFICER_TANSKY GPWS GREG_FEITH GREG_PHILLIPS INVESTIGATOR JEFF_GUZZETTI JOE_EPPERSON JOHN_COX JOHN_GOGLIA JOHN_LIOTINE LAX_CONTROLLER LEAD_INVESTIGATOR MALCOLM_BRENNER MARCIA_POLITOVICH MARY_SCHIAVO MECHANIC NARRATION STEVE_FREDRICK TODD_CURTIS TOM_HAUETER NARRATION The pilots of an MD- suddenly lose control. Without warning, an ATR rolls to the right. Two Boeing s suffer the same deadly fate after going into sudden dives. These are the toughest cases to solve. Speeding planes dive nose first into the ground. Investigators in three cases hunt for answers when pilots lose control of their planes� pitch. Alaska Airlines Flight climbs into sunny skies over Puerto Vallarta, Mexico, carrying passengers and five crew. Captain Ted Thompson is an Air Force veteran. First Officer Bill Tansky has been flying for almost four decades. The MD- will be stopping over in San Francisco before heading to its final destination Seattle, Washington. But fifteen minutes after taking off, there�s a problem. The nose of the plane is dropping, and First Officer Tansky must wrestle with the control column to keep the plane climbing. Twenty-one minutes into the flight, they level off at , feet � but it appears the stabilizer is jammed. The autopilot is keeping the plane at the correct altitude, but Captain Thompson has no idea how long that will continue. He�s worried about the stabilizer so decides to divert to Los Angeles Airport. Thompson contacts Alaska Airlines dispatch in Seattle. Flight goes into a dive. The speed brakes are moveable surfaces on the wings that increase drag. The maneuver works. The plane has dropped , feet in just seconds. It still requires all their strength to keep the nose of the plane level. The passengers� anxiety grows. As they near Los Angeles, the pilots prepare for an emergency landing. But at that moment, disaster strikes. Flight continues to roll left and dive. Rescuers search for survivors. They find none. All passengers and crew on board Flight are dead. Investigators from the National Transportation Safety Board, the NTSB, are assigned to find an explanation for the crash. The leading edge of the horizontal stabilizer is raised or lowered by a jackscrew. The jackscrew changes the stabilizer�s angle as it moves through an acme nut. Investigators wonder how the horizontal trim system could have failed. Recovering parts of the stabilizer system could give investigators important clues. But the wreckage field lies on the bottom of the ocean, beyond the reach of divers. Nine days into the investigation, remotely-operated vehicles, equipped with robotic arms, retrieve the parts investigators are looking for. Systems Investigator Jeff Guzzetti immediately spots a problem with the jackscrew assembly. Threads inside the nut should hold the jackscrew securely in place. But these threads failed. Metallurgist Joe Epperson examines the stripped nut and the jackscrew. In flight, the jackscrew rotates inside the nut. To prevent wear, it needs to be lubricated frequently. During maintenance, grease is applied to the interior of the nut through a small valve called a zerk fitting � but the valve is blocked. NTSB investigators track down the mechanic who serviced the jackscrew and acme nut on the Alaska Airlines MD- four months before it crashed. But it�s not just the way the jackscrew assembly was lubricated that bothers investigators. They discover longer and longer periods between lubrications. Those intervals are measured by the number of hours the plane is in the air. Was the jackscrew assembly on Flight inspected when and how it should have been? The team finds paperwork showing that a mechanic determined the acme nut was badly worn more than two years before the crash. Investigators contact John Liotine, the mechanic who reported the worn acme nut on Flight . But when investigators probe further, they learn that another mechanic cancelled the order to replace the nut. That mechanic determined that it was still within safe limits and cleared the plane to fly. In the wake of the investigation, federal regulators reduced the interval between jackscrew lubrications at Alaska Airlines from hours to hours. Poor maintenance can play havoc with even the best-designed aircraft. But sometimes, flaws can develop while a plane is still on the drawing board. There are passengers on board American Eagle Flight , as it approaches Chicago�s O�Hare Airport. Fog and reduced visibility at O�Hare are jamming up traffic and creating delays. Captain Orlando Aguiar is in command of the ATR . He programs the autopilot to keep the plane circling at ten thousand feet . The circling turn keeps the plane�s nose pitched up. First Officer Jeff Gagliano extends the flaps to fifteen degrees and the aircraft levels out. A half hour later, Air Traffic Control directs the flight to a lower altitude. The overspeed warning sounds. The plane is going too fast to fly with extended flaps. Gagliano retracts them. Suddenly, the plane banks sharply to the right. The control column is stuck. American Eagle Flight is an uncontrolled dive. The pilots fight to pull out of it and level off. Flight crashes in a field just outside Roselawn, Indiana. All people onboard are killed. The next morning, an NTSB team is on the scene. Amidst the destruction, the airplane's two flight recorders are found intact. While the voice and data recordings are analyzed, investigators focus on the holding pattern the flight was put into by Air Traffic Control. Chief Investigator Greg Feith wants to know more about the weather during the hold. Pilots of other planes circling O�Hare airport that day point investigators towards an important clue. Icing is a well-known threat to all aircraft. Examining weather records from the day of the crash, investigators discover that during the -minute holding pattern, Flight repeatedly passed through cloudbanks. But did the pilots know they were flying into icy conditions? The cockpit voice recorder provides the answer. Nine minutes before the crash, they noticed their plane was picking up ice. Feith and his team wonder what the crew did about it. They turn to the flight data recorder. It indicates that almost seventeen minutes before the crash, the master caution warning went off. In response, Captain Aguiar turned the plane�s de-icing system to its maximum setting. But was the de-icing system working? Normally, a rubber boot inflates to break ice that coats the surface of the leading edge of the wing. The force of the crash has left markings that show the position of the valves at the time of impact. Those markings indicate the plane�s de-icing system was working properly. So if there wasn�t a problem with the de-icing system, what else could have caused the crash? Other pilots believe they know the answer � and decide to act. The brochure says the ATR fleet operated by American Eagle is dangerous in icing conditions, and the airline is doing nothing about it. A month after the crash, pilot frustration boils over. A group of a dozen pilots refuses to fly the ATR, citing risky weather. The public protest leads investigators to take a closer look at the aircraft�s vulnerability to ice. The NTSB�s Charley Pereira visits the ATR�s French manufacturer, Aerospatiale. He finds a disturbing pattern. In December , an American Eagle ATR preparing to land in icy conditions suddenly pitched down and stalled without warning. The pilots recovered by boosting engine power. But other flights end differently. In October , an ATR en route to Germany crashed, killing all thirty-seven people on board. The investigation found that ice was a factor but placed the blame on pilot procedures. Charley Pereira wants to know if the engineers who built the ATR series can explain why the plane would go out of control. What he�s told� ... will shock the airline industry. NTSB investigator Charley Pereira presses engineers for the reasons behind the ATR�s tragic record. If ice builds up behind the boot, the crew has no way to clear it. But how could ice form in that location? Additional weather analysis shows Flight flew into something much more dangerous than freezing rain. Super-cooled large droplets � or SLD � raindrops the size of a human hair that stay in liquid form even when the temperature is below freezing. They only freeze when they contact a solid. On every lap of its holding pattern, Flight flew through layers of cloud that contained these super-cooled droplets. Investigators learn that while ordinary ice accumulates on the leading edge of the wing, where de-icing boots can get rid of it, SLDs slide back over the boots before freezing and form a ridge, out of reach of the de-icing system and beyond the view of the flight crew. Investigators conclude that the ice build-up had no effect on Flight until the plane began its descent to eight thousand feet . The descent increased the plane's airspeed and triggered a warning from the flight computer, telling the pilots they were flying too fast with the flaps extended. The crew then retracted the flaps, but that routine action had a dramatic effect on the plane�s aerodynamics. When the nose lifted, airflow over the ice-laden wing was disrupted. This created powerful turbulence, lifting the aileron on the right wing and causing the plane to roll. The NTSB has uncovered a deadly flaw in a popular airplane. The ATR�s wing design makes it vulnerable to icing. In response, the plane�s French builder, Aerospatiale, makes the de-icing boots wider, so they cover a larger part of the wing. It took more than a year to wrap up the investigation into Flight . But the factors involved in other planes� pitch problems can be so rare and unusual, that it takes several years to solve the mystery. United Airlines Flight is on final approach into Colorado Springs with passengers and five crew on board. The skies are clear, but heavy turbulence is rocking the flight. At the controls is -year-old Captain Harold Green. Green�s co-pilot is Patricia Eidson. At Colorado Springs Municipal Airport, controllers are ready to bring Flight in. Suddenly, the spins out of control. Flight is in a mile-an-hour dive. It crashes less than four miles from the runway. The shattered remains of United Airlines Flight lie buried in a fire-blackened impact crater. Rescue workers arrive within minutes. None of the people on board have survived. By nightfall, NTSB investigators are on site. The black boxes are extracted from the site and sent to the lab in Washington. While poring over the voice recordings, human performance specialist Malcolm Brenner hears nothing to indicate that the pilots struggled with the approach. Investigators examine the plane�s wings and tail assembly. The violence of the crash makes recovering these parts a daunting challenge. But a vital component of the tail assembly is mostly intact the power control unit, or PCU. When a pilot pushes on a rudder pedal, the PCU uses hydraulic fluid to convert movements into the pressure needed to move the �s rudder. Inside the PCU, a dual servo valve directs the flow of pressurized hydraulic fluid that moves the rudder. When a technician opens the power control unit, chips of metal are found floating in the hydraulic fluid. It�s an eye-opening find. Could these particles have caused the servo-valve to jam? Testing produces no evidence that they led to the loss of control. Over the next months, investigators rule out pilot error, mechanical failure and weather. Then, for only the fourth time in its history, the NTSB releases a report which doesn�t identify a cause. Two years later, US Air Flight approaches Pittsburgh. It hits a patch of turbulence. The suddenly rolls left. Nothing the pilots do can pull the plane out of the dive. First responders arrive quickly, but there�s no hope for the passengers and crew. NTSB investigators arrive at the site of a second Boeing crash. Eyewitness accounts, along with voice and data from the flight recorders indicate Flight suddenly rolled� and then dived. It matches what happened aboard United . Almost immediately, investigators make a promising discovery. Much of US Air �s tail and rudder appear intact. The hydraulic devices inside the tail have also sustained very little damage. The primary suspect is again the dual servo valve. Just like in the earlier crash, tiny chips of metal are found floating in the hydraulic fluid. Investigators need a break in the case. On June the th, , they get one. An Eastwind is on final approach to Richmond, Virginia, when, without warning, it rolls sharply to the right. Then, suddenly, the unknown forces holding the jet let go. The Eastwind lands safely. The next day, the NTSB team arrives in Richmond. NTSB investigators quickly determine that what happened onboard Eastwind Flight is alarmingly similar to events on flights and . They question the Eastwind pilots. Investigators immediately focus their attention on Eastwind�s rudder controls. The PCU is removed, inspected and tested again and again. To everyone�s frustration, the unit performs perfectly. Investigators go back to the control unit from US Air Flight and put it through more extreme testing. The PCU is super-cooled to simulate the minus -degree temperatures at , feet . Then, it�s quickly injected with super-heated hydraulic fluid. It appears that the small hydraulic valve that controls the rudder of the Boeing can jam in certain circumstances. But that�s not all. It is a stunning revelation. Not only can the dual servo valve jam, but it can also cause the rudder to reverse. To the very end, the pilots of Flight had pushed hard, hoping the rudder would help pull them out of a deadly spiral. But they had no way of knowing they were making the plane�s drastic roll even worse. Re-evaluating the data of United Flight , investigators conclude its flight crew fell victim to the same malfunction. It took less than ten seconds to go from rudder reversal to impact. In the aftermath of the investigation, sweeping changes are made to improve the safety of the Boeing . The federal regulator directs Boeing to redesign the rudder�s dual servo valve to eliminate the potential for reversal and to replace those valves on thousands of s around the world. It took the NTSB ten years to solve the mysterious crashes of Flights and , the longest investigation in its history. A pitch problem can cause catastrophe so total that evidence is scarce. But by revealing deeply hidden flaws, these three grueling investigations changed aviation and made the skies safer. CAPTAIN THOMPSON Okay. It... it really wants to pitch down. JOHN COX They need to find a way to control the pitch of the jet. CAPTAIN AGUIAR Level it out. Level it out. STEVE FREDRICK That airplane can fall out from under them in the blink of an eye. MARY SCHIAVO If a pilot cannot control the pitch system, literally that means the pilot cannot control the plane. GREG FEITH There was very little left of the airplane. JEFF GUZZETTI The plane pitched full nose trim down. GREG PHILLIPS It just jammed. It stopped working completely. Take a look. TOM HAUETER I never allowed myself to think this investigation could go undetermined. FIRST OFFICER TANSKY Gear up. CAPTAIN THOMPSON Gear�s up. FIRST OFFICER TANSKY Thank you, sir. JOHN COX The pilots on were highly regarded. These were really top-notch aviators. FIRST OFFICER TANSKY It�s pushing down. JOHN COX Increasingly there�s more and more pressure that he's having to hold. CAPTAIN THOMPSON All right. Well, we�re still climbing. CAPTAIN THOMPSON No dice. FIRST OFFICER TANSKY Let�s try it on autopilot. The plane is steady. CAPTAIN THOMPSON All right. I'm thinking we get this plane on the ground sooner rather than later. CAPTAIN THOMPSON Dispatch, Requesting a diversion to LAX. Our longitudinal trim system is inoperative. ALASKA AIRLINES DISPATCH Dispatch Copy that. CAPTAIN THOMPSON This'll click the autopilot off. AUTOMATION Stabilizer motion. Stabilizer motion. CAPTAIN THOMPSON Holy crap! CAPTAIN THOMPSON It got worse. Center, Alaska We are in a dive here. I've lost control of vertical pitch. LAX CONTROLLER Alaska , say again sir. CAPTAIN THOMPSON We are in a vertical dive at Uh speed brakes. CAPTAIN THOMPSON Okay. Once we get the speed slowed, maybe we'll be okay. CAPTAIN THOMPSON We've got it back under control here. FIRST OFFICER TANSKY No, we don't. CAPTAIN THOMPSON Okay. It really wants to pitch down. JOHN COX They�re in a, a fight for control of the airplane. FIRST OFFICER TANSKY We better talk to the people back there. CAPTAIN THOMPSON Yeah, I know. Folks, we�ve had a flight control problem. We�re, uh, intending to go to Los Angeles. We�re working on it, and I don't anticipate any problems once we get a couple systems, uh, back on the line. CAPTAIN THOMPSON Okay, we�re pretty stable here, but we gotta get down to a hundred and eighty knots . JOHN COX They need to find a way to control the pitch of the jet. FIRST OFFICER TANSKY If it's controllable, we oughta just try and land it. MARY SCHIAVO They would not be able to pull the plane up and do a go-around. They had one shot to get it on the ground or all would be lost. FIRST OFFICER TANSKY Do you feel that? CAPTAIN THOMPSON Yeah. JOHN COX The airplane pitched down and rolled. This is pilots� nightmare. FIRST OFFICER TANSKY Mayday! CAPTAIN THOMPSON Ugh. Push and roll. Push and roll. GPWS Pull up. Terrain. MARY SCHIAVO And this is like an airshow maneuver. CAPTAIN THOMPSON Okay. We are inverted. Now we gotta get it up. JOHN COX They've got to get the airplane back right side up. MARY SCHIAVO Their one hope is if they could kick that rudder, they could flip the plane back over. CAPTAIN THOMPSON Okay. Let's kick rudder. Left rudder. Left rudder. MARY SCHIAVO The pilots are kind of hanging upside down like bats, and it was very difficult to reach the rudder pedal. FIRST OFFICER TANSKY I can't reach it! CAPTAIN THOMPSON Okay. We�ve gotta get it over again. Speed brakes. MARY SCHIAVO They were giving everything they had. JOHN COX The windscreen�s full of the ocean. They�re not gonna solve this. CAPTAIN THOMPSON Ahhhh! Here we gooooo! JEFF GUZZETTI LAX is saying the pilots reported a jammed stabilizer. JEFF GUZZETTI We knew quite a lot just from the transmissions between the flight crew and Los Angeles. JEFF GUZZETTI The plane pitched full nose trim down. JEFF GUZZETTI We immediately began to research the horizontal stabilizer trim system LEAD INVESTIGATOR We need to see the jackscrew assembly. JEFF GUZZETTI I�ll get this to the Navy. INVESTIGATOR We got the jackscrew. JEFF GUZZETTI With the brainpower we had, we had a fighting chance to find out exactly what went wrong during this flight. JEFF GUZZETTI Why isn�t the nut attached to the jackscrew? JEFF GUZZETTI When we looked at that, we asked ourselves, how can that happen? JEFF GUZZETTI Incredible. LEAD INVESTIGATOR It�s completely stripped. JEFF GUZZETTI No one thought that you could get those thick threads to rip out. JOE EPPERSON There�s some grease here on the bottom. JOE EPPERSON The way to prevent wear is by lubrication, with grease. JOE EPPERSON In the case of a� an extreme wear event, you want to look at is there grease where it�s supposed to be? JOE EPPERSON There should be more grease here in the middle. JOE EPPERSON There was very minimal signs that there was any grease on it at all. JEFF GUZZETTI So the Zerk fitting is this fitting right here, and what mechanics have to do is put a grease gun hose in here and then squirt grease into this little grease fitting that goes inside this passage. That Zerk fitting should have preserved and kept the remnants of whatever grease it saw last. JOE EPPERSON It�s packed with dried grease. LEAD INVESTIGATOR How long has it been clogged like this? JOE EPPERSON At least a year. Maybe more. JOE EPPERSON I�ve been around grease long enough to know that if you don't replenish it and if you just leave it, eventually it dries up and gets hard, and it basically says that it had not been replenished. JOE EPPERSON I�d say we have a maintenance issue here. JEFF GUZZETTI Could you walk us through how you lubricate the jackscrew assembly? JEFF GUZZETTI We were very suspicious about how well this component was lubricated. MECHANIC We use a grease gun through the zerk fitting. JEFF GUZZETTI Well how do you know whether the lubrication is being done properly and when to stop pumping the grease gun? MECHANIC I don't. JOHN GOGLIA He couldn't have known that that zerk fitting has taken grease. You have no idea that it's clogged. LEAD INVESTIGATOR The last time the jackscrew was lubricated was about four months before the accident. JEFF GUZZETTI And before that? LEAD INVESTIGATOR January . They�re doing it every hours. LEAD INVESTIGATOR Check it out. The airline made multiple requests to extend the intervals on the lubrications. In , the interval between lubrications was hours. LEAD INVESTIGATOR In , it goes up to hours. By , it increases all the way up to hours. JOHN GOGLIA If you�re gonna extend these lubrication functions, then you... you better be doing something to make sure that what you�re doing is correct. JEFF GUZZETTI But even if the lubrication wasn't being done properly, regular inspections should have caught the wear on that acme nut. JEFF GUZZETTI We looked at the maintenance records for information about the last check. LEAD INVESTIGATOR Yeah, this doesn't look right to me. JOHN LIOTINE You�re sure the reading is point zero four zero? LEAD INVESTIGATOR The lead mechanic ordered the nut to be replaced. JEFF GUZZETTI This was evidence that someone had caught the fact that this acme nut was worn out. JOHN GOGLIA Most airlines, the decision would be We will get the piece to the airplane as soon as possible and replace it. JEFF GUZZETTI Do you remember inspecting an MD- on September th, ? JOHN LIOTINE I remember it well. JOHN LIOTINE I wrote up the evaluation. The nut is worn down. Replace it. JEFF GUZZETTI How could a maintenance facility allow the airplane to be put back into revenue service with the wear that it found on the acme nut? This accident could have been prevented. MARY SCHIAVO Literally cents worth of grease cost a planeload of people their lives. MARY SCHIAVO Looking back, it makes no sense at all. They decided you could put off maintenance, put off maintenance and put off maintenance, with the approval, I might add, of the authorities in the airline who allowed greasing their parts to be extended almost indefinitely. CAPTAIN AGUIAR Chicago Center, we have discretion down to, uh, one zero thousand . We�re on our way down now. CONTROLLER Eagle -, roger. CONTROLLER Eagle --, hold southeast on Victor Seven. CAPTAIN AGUIAR Chicago Center, roger, hold southeast on Victor Seven. Eagle --. CAPTAIN AGUIAR This thing gets a real high deck angle in these turns. FIRST OFFICER GAGLIANO Yeah. FIRST OFFICER GAGLIANO You want flaps fifteen? CAPTAIN AGUIAR It'll bring the nose down. FIRST OFFICER GAGLIANO That's much nicer, flaps fifteen. CAPTAIN AGUIAR I'm sure once they let us out of the hold and forget they're down, we'll get the over-speed warning. CONTROLLER Eagle Flight --, descend and maintain eight thousand . FIRST OFFICER GAGLIANO Down to eight thousand . Eagle --. CONTROLLER Eagle Flight --, uh, should be about ten minutes, uh, till you're cleared in. FIRST OFFICER GAGLIANO Thank you. CAPTAIN AGUIAR Are we out of the hold? FIRST OFFICER GAGLIANO No. We're just going to eight thousand . CAPTAIN AGUIAR Ah. I knew we�d do that. FIRST OFFICER GAGLIANO I was trying to keep it at one-eighty. CAPTAIN AGUIAR Ah! CAPTAIN AGUIAR Ugh! CAPTAIN AGUIAR Level it out. Level out. GPWS Terrain. CAPTAIN AGUIAR That�s it. GPWS Pull up. CAPTAIN AGUIAR Nice and easy. GPWS Terrain. Pull up. Terrain. Pull up. GREG FEITH It was one of those types of accidents where there was very little left of the airplane. CONTROLLER Eagle --, hold southeast on Victor Seven. CAPTAIN AGUIAR Well folks, I do regret to inform you that Air Traffic Control has put us into a holding pattern up here. GREG FEITH When we looked at the air traffic control records, we found that the flow rate � that is, the number of airplanes that were going into Chicago O�Hare at the time � had to be reduced because of the weather moving through the area. GREG FEITH I want weather data, pilot reports, atmospheric conditions, Doppler radar, anything you can find. GREG FEITH They all experienced icing, some as much as three quarters of an inch. MARCIA POLITOVICH It creates drag. It reduces lift. It causes performance and handling problems. GREG FEITH we knew had been holding in an icing event. There were layers of clouds that they had been flying in and out of. FIRST OFFICER GAGLIANO That�s much nicer now, flaps fifteen. CAPTAIN AGUIAR Yeah. FIRST OFFICER GAGLIANO I'm showing some ice now. BOB SWAIM The key component to the de-icing system is probably not the black rubber boot that you see on the airplane, but the timer in the valves that control those boots. FIRST OFFICER GAGLIANO Showing some ice now. STEVE FREDRICK I distributed a brochure, which essentially warned people about the problems with the ATR aircraft. CHARLEY PEREIRA We embarked on a research effort to try to identify all previous ATR and , uh, roll control incidents. CHARLEY PEREIRA And about five... five of those were found to be similar, after the fact, in our review to the Roselawn case. GPWS Terrain. Terrain. GREG FEITH For investigators, it's really important to look back at historical information about any airplane. CHARLEY PEREIRA Did any of your studies uncover a wing design flaw? FIRST OFFICER GAGLIANO We still got ice. CHARLEY PEREIRA You�ve seen the flight data from the accident flight. Where would the ice have formed to cause that? CHARLEY PEREIRA When I asked one of their oldest, most senior aerodynamicists what he thought would cause, uh, the behaviour that we saw on the flight recorder for the Roselawn airplane, he drew up a little shape just behind the de-ice boots. CHARLEY PEREIRA Aft of the de-icing boot. FIRST OFFICER GAGLIANO We still got ice. MARCIA POLITOVICH A warm cloud top minus- to minus- degrees C. We had drizzle formation near the top that was probably encouraged by some wind shear near the cloud top. They just put that poor guy in the wrong place at the wrong time. CONTROLLER Eagle Flight -- descend and maintain eight thousand .. FIRST OFFICER GAGLIANO Down to eight thousand .. Eagle --. CAPTAIN AGUIAR I knew we'd do that. FIRST OFFICER GAGLIANO I was trying to keep it at one-eighty. GREG FEITH When they retracted the flaps as they started their descent down to eight thousand feet , the airplane pitched back up into a very nose-high attitude. GREG FEITH The forces were determined to be about pounds . So for the pilot, it would have been trying to roll against pounds of aerodynamic force. FIRST OFFICER GAGLIANO Damn! TODD CURTIS Several things had to go wrong for this to happen and it's only because of the very detailed investigation in these accidents that these were able to be resolved, so that it would not happen again. CAPTAIN GREEN Nice looking day. Hard to believe the skies are unfriendly. CAPTAIN GREEN Flight attendants prepare for landing. CONTROLLER United -- is cleared for a visual approach to runway . CAPTAIN GREEN Starting on down. CAPTAIN GREEN No! No! FIRST OFFICER EIDSON Oh my god! Oh my god! GREG PHILLIPS My first sense that it was going to take some time in� to investigate the accident was, was the damage that we saw on the parts. When they�re burned and broken, uh, the process always takes longer. MALCOLM BRENNER This is a sense of a, of an, an excellent crew caught randomly, if anything. So, again, that was my first impression is that this would be consistent more with a hardware situation. GREG PHILLIPS After eliminating other flight control surfaces that we thought could contribute to the roll, we started looking at the rudder. GREG PHILLIPS Almost nothing left. GREG PHILLIPS We didn�t have any absolute indication or information that we could point to that said the rudder power control unit, the servo valve or any, any part of that flight control system caused that accident. GREG PHILLIPS We had put a lot of time and effort in� into the investigation and we just weren�t sure what had happened. FIRST OFFICER EMMETT Oh geez. FIRST OFFICER EMMETT Hold on, hold on. Hold on. CAPTAIN GERMANO What the hell is this? Shoot! emergency! FIRST OFFICER EMMETT Oh shoot! CAPTAIN GERMANO Pull! Pull! FIRST OFFICER EMMETT Oh God. Oh God, no! Nooo! TOM HAUETER There was no aircraft there. There were only bits and pieces of the airplane. It wasn�t really recognizable as an airplane. TOM HAUETER Certainly, the whole team was aware of the previous accident with United in Colorado Springs. We tried to keep that in the back of our minds and take a look at this one as to what it presents to us. TOM HAUETER Careful with it. GREG PHILLIPS There wasn�t any indication that it had failed and it, it operated within the parameters we expected it to. JOHN COX We were all frustrated as months wore into years. What were we missing? BRIAN BISHOP We knew we had a problem with the rudder. I turned the yoke the opposite direction and stood on the opposite rudder pedal. The pedal didn�t move for me. BRIAN BISHOP In a matter of seconds, it released itself and went back to normal. GREG PHILLIPS The airplane literally didn�t move. It stayed at its location at the airport �til we got down there. BILL ADAIR It gave the NTSB, uh, a tremendous break because suddenly they had a that had had a rudder incident, that was intact, and they had a pilot who was alive and who could talk about it. MALCOLM BRENNER And, and when we said, well what happened? They said, there was something wrong with the rudder pedal. The pedal wouldn�t go down. I was standing on the rudder pedal and I couldn�t get it to go down. My god. TOM HAUETER We tested that aircraft as is. It was intact. We went through it completely. We did flight tests with it. And it passed all tests. TOM HAUETER Well one fellow mentioned a test they had done in the military of a thermal shock where if you had the actuator being very cold and put in very hot hydraulic fluid, it would cause it to react in strange ways. So we put together a thermal shock test. JOHN COX As we were standing there listening to the, the actuator move left and right, left and right... it stopped, and it was not commanded to stop. GREG PHILLIPS It just jammed, stopped working completely. BILL ADAIR The most important breakthrough came when a Boeing engineer, examining the data from that test, discovered some numbers that indicated the valve at that point had actually reversed. TOM HAUETER You turn to the right, it goes left. That�s what the pilots were faced with, something so unusual that they didn�t understand what was happening. CAPTAIN GREEN Flight attendants prepare for landing. MALCOLM BRENNER Going back to Colorado Springs, you could follow a progression of what the captain was doing. He�s close to the ground and suddenly under rudder reversal he puts in a little bit of pedal. The pedal violently pushes his leg back. FIRST OFFICER EIDSON Oh God! CAPTAIN GREEN Fifteen flaps. FIRST OFFICER EIDSON Fifteen. MALCOLM BRENNER Rudder reversal certainly fits what I know about this crew. TOM HAUETER We were able to show the failure mode. It matched the flight data recorder from each aircraft. It fit like a glove. FIRST OFFICER EIDSON Oh my God! TOM HAUETER One thing we don�t like at the Safety Board is to have an undetermined accident, because then we can�t make a change to improve safety. So out of US Air , United , we have a much safer fleet. MARY SCHIAVO You know the first thing people say is, oh, who would have thought this could happen? But when they go back and look at the data often it's there. It was a problem waiting to happen. TODD CURTIS The biggest lesson to take away for the industry and for the public at large is that in a complex accident such as this, the answers may not come in a few months or even a few years. Sometimes it would take several events in order to piece together a pattern that reveals the answer. National Geographic Air Crash Investigation Special Report Ep. Final Air Crash Investigation Special Report 1 //