FLIGHT 427 FLIGHT 427 Anatomy of an Air Disaster

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Library of Congress Cataloging-in-Publication Data Byrne, Gerry. Flight 427 : anatomy of an air disaster / Gerry Byme. p. cm. Includes bibliographical references and index. ISBN 978-1-4419-2923-5 ISBN 978-14757-5237-3 (eBook) DOI 10.1007/978-1-4757-5237-3 1. USAir Flight 427 Crash, 1994. 2. Aircraft accidents-Pennsylvania• Hopewell (Beaver County: Township). 3. Aircraft accidents• Investigation-United States. I. TItle. TL553.525.P4 B97 2002 363.12'465-dc21 2002022483

Printed on acid-free paper.

987 6 5 4 3 2 1

SPIN 10796069 ISBN 978-1-4419-2923-5 FOT Marie, my wife, who had faith in me when I didn't IX PrefGCe X Aclrnowledgments XIII Introduction

1 Part One 585

3 ChGpter 1 THE UNFRIENDLY SKIES 17 ChGpter 2 TIN KICKERS 29 ChGpter 3 LOOKING FOR ANSWERS 45 ChGpter 4 RECONSTRUCTING THE WIND 55 ChGpter 5 WE HAVE A PROBLEM

73 PartTwo 427

75 ChGpter 6 OUT OF THE SKY 87 ChGpter 7 HA TARGET HAS DISAPPEAREDH 99 ChGpter 8 SITUATION: NON-NORMAL 109 ChGpter 9 PUMPS AND VALVES 123 ChGpter 10 SECRETS OF THE FLiGHT DATA RECORDER 135 ChGpter II THE FIRST PUBLIC HEARING 147 ChGpter 12 HUMAN FACTORS 167 ChGpter 13 ATLANTIC CITY 179 ChGpter 14 JIM HALL STEPS IN 191 ChGpter 15 HUMAN FACTORS REVISITED

201 Part Three 517 AND AFTER

2°3 ChGpter 16 THE EASTWIND INCIDENT 21 9 ChGpter 17 BOEING ON THE HOOK 231 ChGpter 18 REVERSALS 243 ChGpter 19 SUBMISSIONS 253 ChGpter 20 FINDINGS 267 ChGpter 21 EPILOGUE

279 Index PREFACE

This book tells the story of the 1994 crash of a commercial jetliner on its final approach to Pittsburgh International Airport. The disaster that struck the plane, USAir Flight 427, killed all 132 passengers and crew on board, and as with all such tragic crashes, this one created a momentary surge of public grief and a brief rush of interest from the media. But it was not the type of crash to draw the intense, sustained fascination of Pan Am Flight 103, which exploded over Lockerbie, Scotland, in 1988, or TWA Flight 800, which plunged into the sea off the co ast of Long Island in 1996. However tragic an event it was, to most of the public it shortly became just an "ordinary," not particularly memorable, disaster. But of course there was almost nothing ordinary about it. This is primarily the story of the dozens of investigators who sorted through the wreckage, and the scientists and engineers who ultimately solved the puzzle at the he art of this and perhaps several other disasters. And there is a wrinkle to the story: one of the "characters," perhaps the central character, is not a human at all, but an airplane. Until the National Transportation Safety Board (NTSB) delivered its official verdict on the accident in March of 1999, its cause had been one of US avia• tion's longest-running puzzles. This book explains why it took so long to get to the bottom of this mystery. Beginning with the investigation of an earlier crash, United Airlines Flight 585, this books shows how only after almost a decade of probing did the bril• liant sleuthing and informed hunches of the "tin kickers" at the NTSB pay off• uncovering a rare but nonetheless fatal flaw in the design of the Boeing 737. This plane, the "work horse" of modern commercial airlines, is indisputably the most popular and arguably the safest of all major airliners. Yet the diffi• culty of getting to the bottom of the 737's problem, and the sometimes com• peting and sometimes overlapping interests of its manufacturer, the airlines, the pilots' union, the families of those killed, and most of all two agencies of the US government-the Federal Aviation Administration and the National Transportation and Safety Board-come together here in what, after all is said and done, is a kind of engineering detective story.

GerryByrne Dublin, Ireland ]anuary 2002 IX ACKNOWLEDGMENTS

Although I have only ever been unfortunate enough to be present at the imme• diate aftermath of one fatal airplane crash, it made an everlasting impression on me. When emergency services allowed my photographer and me into the woods where the four-seater had crashed, killing all aboard, I discovered that I had not long before interviewed its owner-pilot, who had built the aircraft in his own garage. But even this sad, searing memory fades into insignificance with the haunting recollections of one Washington evening, listening to the stories being told by men and women whose lives had been dramatically changed by air accidents. There were airline crash survivors like Tom Eilers, who crawled dazed, almost losing his will to live, out of the burning wreck of a DC-10 at Sioux City, from which 111less fortunate souls like Tom O'Mara's daughter never emerged. The heartbreaking stories of people like Carole Rietz, who lost a wonderful son in the ValuJet Everglades crash of 1996, graphically illustrated the horrific impact of an airliner crash on relatives of victims, people who often carry mixed burdens of grief, anger, depression, and even pointless guilt for years afterwards. This book is not about their suffering-it is about discovering why air• planes crash-but their experiences and their courage have deeply inspired me on this journey into the wonderful world of flight, and the bleak world of airplane accidents. Apart from inspiration, no writer can cope without good sources, and I must give thanks to as many as I can. Although not direct sources for this book, a few deserve special mention. Fellow journalist Tom Clark, who first pointed me at this story; Gail Dunharn, whose ex-husband, Captain Harold Green, died in the crash of Flight 585 at Colorado Springs, and who goaded me on; the editors at New Scientist, who published my initial efforts; Dan Loughrey and Willie Walsh, who squeezed me between the cracks into a Boeing 737 simulator so I could learn how 737s were flown instead of eternally marveling at the apparent wizardry of it all; the various Aer Lingus and Ryanair captains, who, over the years, tolerated me in their cockpits to watch them fly; and the air traffic controllers at Dublin, Ireland, who occasion• ally suffered me at their elbows. An immense quantity of research material was provided by the National Transportation Safety Board, in Washington, D.C., which also provided me with access to many of its key personnel for interviews. They included Tom Hauteur, investigator in charge (Flight 427); Al Dickinson, investigator in charge x (Flight 585); Greg Phillips, Systems Group chairman; Malcolm Brenner, Human Factors Group chairman; Cynthia Keegan, Structures Group chairman; Frank Hildrup, Structures Group member; Al Lebo, Air Traffic Control Group chair• man; Greg Salotollo, Meteorological Group chairman (Flight 585); Tom Jacky, Aircraft Performance Group chairman (Flight 427) and Flight Data Recorder Group chairman (Flight 585); Dennis Crider, kinematics, and Jim Cash, acoustic expert. Although they did no work on either of the main crashes featured in this book, Jim Hookey (Powerplants) and Nora Marshall (Survival Factors) kindly and patiently explained how their colleagues went about their work. Jamie Finch and Sharon Bryson described the work ofthe Family Affairs Office, and Ted Lopatkiewicz from Public Affairs coordinated things splendidly. Former NTSB chairman Jim Hall came out of retirement, as it were, to dis• cuss Flight 427 with me, as did former NTSB board member Bob Francis, in addition to Bernie Loeb, former head of the Office of Aviation Safety; Ron Schleede, former deputy director of the Office of Aviation Safety; and Chuck Leonard, who had led the first Operations Group on Flight 427. Some other former NTSB and Boeing staffers spoke to me but requested that I preserve their anonymity. Many perplexing questions about Rocky Mountain weather were answered by Al Bedard of the National Oceanic and Atmospheric Administra• tion, Terry Clark of the National Center for Atmospheric Research, and Professor John Marwitz, formerly of the Atmospheric Science Department of the University ofWyoming at Laramie. Paul Knerr of Canyon Engineering led me through the topic of silting in airplane hydraulics, and Michael Demetrio of Corboy & Demetrio spoke to me about the legal process followed by relatives. I was aided by several pHots, including Captain John Cox, who was an ALPA delegate to the Systems Group; Captain Robert Sumwalt, an ALPA dele• gate to the Human Factors Group; and Captain Joe Kohler, who represented ALPA on the Engineering Test and Evaluation Board. Dave King of the United Kingdom Air Accident Investigation Branch provided an interesting foreign perspective on the investigation. I leaned heavily on the work of some other authors, especially Macarthur Job, whose excellent and brilliantly illustrated series Air Disasters (Volumes 1-3) is the closest thing there is to an encyclopedia of airliner crashes, and which was alm ost always open on my desk. I also consulted Christine Negroni's Deadly Departure (HarperCollins, 2000) about TWA 800, and Stephen Frederick's Unheeded Warning (McGraw-Hill, 1996) for the background to the Roselawn, Indiana, crash. Andrew Weir's The Tombstone Imperative (Sirnon & Schuster, 1999) provided illuminating analysis of a wide range of air disasters. Also consulted were Nicholas Faith's Black Box (Boxtree, 1996), Stanley Stew• art's Emergency: Crisis on the Flight Deck (Airlife, 1999), and Aircraft Accident XI Analysis: Final Reports (McGraw-Hill, 2000) by James Walters and Robert Sumwalt. David Beaty's The Naked Pilot (Airlife, 1999) proved a provocative introduction to the topic of human factors in aviation accidents. Robbie Shaw's Boeing 737-300 to 800 (Airlife, 1999) was a useful source on the technology and history of the Boeing 737; other historical perspectives were provided by T. A. Heppenheimer's Thrbulent Skies Oohn Wiley & Sons, 1995) and Matthew Lynn's Birds of Prey (Heinemann, 1995). I found illumination on many questions of aircraft performance in Barnard & Philpott's revision of Kermode's classic, Mechanics ofFIight (Longman, 2000). Inevitably I was drawn to the NTSB's own reports into accidents, especially on Flight 427 and Flight 585, in addition to the report on the Exxon Valdez disaster and others I have analyzed over the years. These take two forms: factual reports by individual groups (e. g., Systems), and the final report drawn together by the investigator in charge and passed by the board of the NTSB. FCj.ctual reports, and the appendices and correspondence they attract, are a vital source ofinformation for the serious student of airplane crash investigation. I also mined the FANs Critical Design Review of the Boeing 737 and the report of the Engineering Test and Evaluation Board (FAA, 2001). The Rand Institute for CivilJustice's study on the NTSB, Safety in the Skies (1999), provided an interesting perspective on the Party System of air crash investigation. Reports in many US newspapers and maga• zines provided invaluable signposts to this story, but nowhere was this story cov• ered with such regularity and depth as in the Seattle 'fimes. Although Boeing had generously cooperated with my researches on other projects, for this one the plane maker adopted a policy of omerta and, not for the first time in connection with Flight 427, refused to sanction interviews by writers with its staff. Readers may draw their own conclusions from this-I offer no suggestions because I have none. However, reconstructing Boeing's participation in this investigation was relatively straightforward from the comments of other parties and because of the large number of reports and let• ters its staffwrote, made available to me from the NTSB's archives. Finally, a special word ofthanks to Paul Farrell, Editor-in-Chief at Coperni• cus Books, and his hard-working colleagues and freelancers: Mareike Paessler, Jordan Rosenblum, Tim Yohn, and Lyman Lyons.

XII INTRODUCTION

When the Wright Brothers first took to the air in Flyer at Kitty Hawk in 1903, they crashed on their fourth flight, setting an unwe1come ratio of accidents to flights for aviation's first year. 'IWenty-eight years later, when a group of 24 pilots gathered to form the first pilots' union, air safety had improved dramat• ically, yet by today's standards it was still appalling; half of those men were destined to die in airliner crashes. It was not until 1954 that air crash casual• ties were first outnumbered by those dying in train wrecks. In that year, three US airliners crashed and 90 people died. Were the same proportion of the trav• eling American public to die today, there would be at least 20 major air disas• ters annually in US airspace, with a death toll in the thousands. Although it is almost unforgivable to attempt to draw comfort from the year 2001, which was blighted by four horrific crashes killing 391 passengers and crew plus thou• sands on the ground as a result of terrorist action-yet there was only one major jetliner crash that year due to what might be called accidental causes: the November 12 crash of an American Airlines Airbus in Queens, New York, killing all 275 aboard. There were two reasons for a gradual, if sometimes erratic, improvement in air accident statistics. First, a legion of rules and regulations about flying were promulgated by Government, initially by the US Department of Com• merce, then the Civil Aeronautics Board and its successor, the Federal Aviation Administration. New airplane designs had to be government-approved. Pilots had to be better trained. They received more accurate weather forecasts. And a nationwide system of air traffic controllers, radar, and radio beacons replaced a haphazard system of lights atop towers and stopped pilots getting lost or flying blindly into each other. A second reason for the reduction in air accidents was the work of air accident investigators, the people whose work on major air accidents fills the pages of this book. Over 75 years, they probed crashes to find out what hap• pened, not so much to allocate blame, but to make sure the same thing never happened again. At first, following the passage of the 1926 Air Commerce Act, they operated as a division of the US Department of Commerce, but later worked within the Civil Aeronautics Board's Bureau of Aviation Safety. The Civil Aeronautics Board evolved into the Federal Aviation Administration (FAA), but then, when it became obvious that government services themselves might be part of the problem in an air disaster, investigators demanded and XIIl secured more autonomy. Congress established the National Transportation Safety Board in 1967 as an autonomous govemment agency. Its independence was further underlined in 1974, when it was removed from the overall control of the US Department of Transportation. Since its creation, the NTSB has investigated more than 115,000 aviation accidents and incidents, mostly related to light aircraft, and issued many thousands of recommendations for the improvement of aviation safety. Although it has powers to subpoena witness and documents, the NTSB cannot make new rules or force airlines or plane makers to change their ways. That role is reserved for the FAA. Apart from its findings of the cause of air accidents, the NSTB can only issue recommendations, mostly to plane makers, to airlines, airport authorities, and, finally, to the FAA. Nevertheless, the NTSB likes to boast that up to 84 percent of its recommendations result in the cre• ation of new rules or the correction of unsafe procedures. But a worrying 16 percent, at least, are ignored or rejected. We now know that at least one major airborne disaster could have been averted if more NTSB recommendations were heeded. After a fire in the cargo hold of an American Airlines DC-9 that landed safely at Nashville in February 1988, the NTSB recommended that smoke detectors, among other fire safety equipment, be installed in the cargo holds of all aircraft. The call went unheeded by the FAA and by the airlines and plane makers, some of whom actively lobbied against the proposal. On May 11, 1996, 110 died when a ValuJet DC-9 crashed in flames into the Florida Everglades while attempting to return to Miami after the crew had discovered a fire raging in the cargo hold shortly after takeoff. A smoke detector could have alerted them earlier, perhaps even before takeoff, and saved many lives. '!Wo years later, the FAA finally mandated the installation of smoke detectors in cargo holds but gave airlines up to three years of grace before fitting them.

This book traces the investigation by the NTSB into the tragedy of USAir Flight 427, which crashed into a lonely hillside outside Pittsburgh in September 1994, killing all 132 aboard. It was a remarkable accident for several reasons. It seemed to have had no obvious cause, and it struck a Boeing 737, arguably among the safest and easily the most popular airplane ever built. It also mir• rored the mysterious crash three and a half years earlier of another 737, this time belonging to United Airlines, with which we commence this story. When United Flight 585 crashed at Colorado Springs one blustery March day in 1991, all 25 aboard died, and the cause was always far from clear. In December 1992, the NTSB admitted it had failed to solve the case of Flight 585, declaring that there was no obvious cause, although it did suggest that either weather or XIV mechanical failure might be to bIarne. Their inability to solve Flight 585 hung like a dark cloud over the investigators. It had become one of just a handful of crashes for which they had failed to find a cause since the NTSB's foundation 25 years earlier. When confronted with a second, apparently insoluble accident at Pittsburgh, the bitter memory of Flight 585 goaded investigators, stinging them like an irritating insect and propelling them into investigating that second crash like no other accident they had ever handled before. In most airliner crashes, good clues usually emerge sooner or later. On the radio to controllers, a pilot may describe an emergency like a fire, an engine failure, loss of control, or atrocious weather conditions. One of the black boxes, the flight data recorder may reveal some anomaly in the airplane's flight behavior. Similarly, the other black box, the cockpit voice recorder, may betray the fact that the pilots are lost, or improperly manipulating the controls, or omitting to follow proper procedures. Should the recorders fail to yield clues, a painstaking search of the wreckage will often yield a fatal flaw. A vital part may have failed due to wear and tear, or lack of maintenance, or improper installation or adjustment. Most crash investigations are weIl on their way to being wrapped up within a year or 18 months. But Flight 585, and Flight 427 afterward, offered no clues whatsoever. Nothing in communications with the tower, nothing in the black boxes, nothing unusual in the wreckage. Reconstruction of the weather conditions the day Flight 585 crashed revealed unusual, freakish winds. Boeing proposed convincingly that they could have downed the aircraft. Investigators were not so sure but left the pos• sibility open, along with mechanical failure. A reconstruction of the flight path followed by FIight 427 in its final seconds showed a remarkable similarity with that of Flight 585, yet the weather that day in Pittsburgh had been almost calm. lt was only when investigators started looking at reports from Boeing 737 pilots whose aircraft had inexplicably misbehaved that the chilling possibility emerged that all Boeing 737 aircraft might possess a fatal design flaw-a freak blemish which, without warning, could tear an otherwise perfect airplane out of the sky in seconds. To inconclusively uncover this flaw took a total of eight years, from when Flight 585 crashed until the NTSB formally delivered its ver• dict on Flight 427. lt had been the longest, most complicated, and one of the most expensive aviation crash probes ever.

Unlike the FAA, which employs some 50,000 people, the NTSB is a small agency. At the time of these crashes, it employed about 400 people divided between its Washington, D.C., headquarters and a network of local field xv offices. Not all worked on air crashes. A significant proportion of them were devoted to accidents on roads, rail, commercial shipping and pleasure boats, and even gas and oil pipelines. In the early days, investigators were sometimes expected to handle accidents across a wide range of modalities but, increas• ingly, they specialized in one mode of transport only. Nevertheless, it was not long since an NTSB psychologist might be asked to investigate the behavior of a ship's captain one day, then probe the background of dead jetliner pilots not long afterward. Skilled, experienced aerospace engineers have always been in strong demand at the NTSB but, despite a small but steady increase in staffing across the years, investigators always found themselves playing catch-up with avia• tion technology. While it was possible that a clever man in a field office might understand every control and rivet in a Cessna 172 or a Piper Cub, the com• plexity of a modem transport category airplane completely rules out that sort of familiarity. In an age of specialization, engineers increasingly attach them• selves to different parts and functions of the airplane. One investigator might be an expert on the structure of an airplane, another on controls, yet another devoting him- or herself entirely to engines. Yet no two airplanes designs were alike. For example, at the time of these accidents, there were two US manufac• turers of large transport aircraft, Boeing and McDonnell Douglas (they have since been merged). A third, Lockheed, had quit passenger aircraft manufac• ture but its L-1011 Tri-Star still plied air routes. Of Boeing aircraft, for example, there were six main models and dozens of variants. McDonnell Douglas had concentrated most of its recent production around two models but, again, there was a large number of variants. In Europe, Airbus was producing almost as wide a range of jetliners as Boeing and had pioneered the use of complex, computerized cockpits. In addition, there were smaller jetliners from Fokker, British Aerospace, and Bombardier/DeHavilland, among others. The picture was just as bewildering at the turboprop end of the commuter aircraft, mainstay of the regional and feeder airlines. Most of those aircraft were coming from French, British, Swedish, Canadian, and even Brazilian manufacturers. Not only was each aircraft make and model built differently, but many models had idiosyncrasies that required unique skills and training to fly them. The Captain of a DC-9 could not possibly hope to step into the cockpit of a Boeing 747 and commence flying it without months of retraining and familiarization. The reverse was also true. For years, the NTSB had recognized that no one investigator could possibly probe all aspects of a major air crash. Instead, under the leadership of a senior investigator (the investigator-in-charge) it deployed a wide range of specialties needed to tackle different aspects of a crash. There is a structures investigator who determines if there are flaws with the wings, or the fuselage, or perhaps XVI even the undercarriage. This investigator usually takes responsibility for the crash site, ensuring that all the wreckage is accounted for and that proper trails of evidence are followed. Another person takes responsibility for the engines, yet another for the aircraft's controls (or systems), while a fourth investigator probes the airline's operations and the crews' training and suit• ability for the flight. A staff psychologist might also get involved to see if there are any hidden aspects of the aircraft or the airline's procedures that trip the unwary into making fatal eITors. Other specialists take charge of the aircraft's black boxes and decipher their contents. Another investigator reviews the accident flight's relationship with air traffic controllers, while a staffmeteorol• ogist analyzes the weather at the time of the crash to determine if it had a bearing on the accident. There are metaHurgists, sound specialists, fire and explosions experts, simulation experts, survival experts, maintenance experts, even pilots, all bearing down with their unique skills in bid to uncover the cause of an accident. Yet many times, this is not enough. The NTSB's experts often need to draw on the knowledge of other investigators, in Britain, in France, sometimes even in the former USSR, to come up with answers to unique problems involving aircraft from those countries, or to help with investigative techniques they have pioneered. British investigators have, for example, long mastered the art of reconstructing wreckage, while Russian specialists have added a new dimension to the interpretation of cockpit voice recorder tapes. US investiga• tors, in turn, are regularly called overseas to help solve crashes involving US• built aircraft. And it is still not enough. The differences between aircraft makes and types is often so great that it might take investigators months, even years, to get fuHy up to speed. Rather than collapse under a mountain of paperwork and study each time an airplane crashes, the NTSB resorts to what it calls the Party System. Any organization even remotely likely to be implicated in an air accident may apply to be affiliated to the investigation as a party. They participate in the probe, perhaps even suggesting avenues of further exploration to investiga• tors. In their turn, the investigators draw upon the knowledge and experience of the party members and use them as a shortcut to obtaining further infor• mation. The plane maker is an obvious starting point. When a Boeing aircraft crashes anywhere in the world, a small team of Seattle-based engineers springs into action. Its composition mirrors that of a typical NTSB team with structures, systems, operations, sometimes even data recorder specialists. Depending on the severity of the accident, they assess the skills likely to be in demand at the crash site. The team, in turn, can draw upon engineers from elsewhere in the company, and within hours a group of spe• cialists is en route to the dis aster scene, ready to assist NTSB personnel make XVII sense of it all. The airline will also dispatch as full a team as it can muster, although only the Federal Aviation Authority is legally entitled to be repre• sented on every investigation. Similarly, an engine manufacturer will also dispatch engineers familiar with the crashed engine's powerplants, a hydraulics company will want to be represented on the team that probes the control systems, the undercarriage manufacturer on the Structures Group, and so forth. Labor unions also get involved. The International Association of Aircraft Machinists attaches volun• teers to several groups, especially Structures, Powerplants, and Systems. And the Airline Pilots' Association (ALPA) is often among the most represented of all the parties. Next to the FAA, the plane maker, and the airline, ALPA is often the only party with delegates on practically every group in an investigation. The NTSB gains ready access to immense quantities ofknowledge, experi• ence, and expertise as a result of the Party System. The benefits to the parties themselves are less obvious but they can be significant. On a more altruistic level, their inputs may lead to a speedy conclusion of a crash probe, hopefully resulting in safety recommendations that will prevent a similar accident from reoccurring. Equally altruistically, ready access to all the data flowing in from an investigation can enable an airline, a plane maker, or a component manu• facturer to take early action to correct any flaws uncovered in its products or processes. Motives can be interpreted as being less altruistic the further one moves along the chain ofbenefits. For example, a party may quickly discover if one of their products (or members, in the ca se of the labor unions) is under suspicion as a probable cause of the accident. If so, they can then present mitigating fac• tors to the investigators or suggest other contributory factors that should also be taken into account, such as poor weather in the event of pilot error, or pilot error in the event of an airplane malfunction, for example. Corporate lawyers can be tipped off if a flood of liability claims is to be expected. (Despite the NTSB's request that information uncovered in an investigation be kept confi• dential until reports are published, this often occurs.) And finally, faced with a situation where a party is likely to have to shoulder the blame for its products, or its affiliates, the desperate option remains of attempting to blame some• thing, or somebody, else. The result is often an interesting tension between investigators and party members during an investigation, a tension which, as can be seen in this book, can occasionally develop into outright hostility. Each investigator acts as chair• man to his or her group, which may include delegates from the FAA, the airline, the plane maker, the pilots' union, the machinists' union, and a component manufacturer. Investigators are usually diplomatie about the dynamics of their groups and in any event claim that other group members are often more XVIII than able to counter any false allegations or misleading scenarios proffered by any one delegate. For example, an unfounded attempt by the airline to blame the crew will be met with a robust rebuttal by the pilots' union, and vice versa. In other words, they will keep each other in check. This process is often very much in evidence during a public hearing, as party representatives cross• examine witnesses. At least one public hearing and possibly also a public board meeting may be held during an investigation. However, the conclusion of the investigation offers parties a further opportunity to influence the final outcome. First, each party chairman will have wrapped up his or her separate investigation. In their final reports, most of these will be able to say that no errors, flaws, or failures were uncovered as part of their investigation, and their groups have been disbanded. Those groups who do discover any unusual factors, or outright failures of machinery, or errors by personnel, will say so in their final reports, wh ich are provided to the investigator in charge. He or she then invites all of the parties to the inves• tigation to submit their take on the accident, what they think may have caused it, and how such an occurrence may be prevented in future. If the issues are straightforward and the parties submit probable causes more or less in agreement with each other, the investigator-in-charge is likely to rapidly draft a finding for transmission to his or her superiors who, in turn, may submit it straight to the board of the NTSB for their adoption. Occasion• ally, however, party submissions offer conflicting, often risible interpretations of the evidence in which case the final process is likely to be slightly more drawn out. Senior NTSB executives will then exhort investigators to check and double-check their conclusions before submitting them to a final, rigorous analysis. Adecision by the board of the NTSB is the culmination of an alm ost judicial process that is very difficult to challenge, even in the courts, so there is tremendous pressure on the staff to get it right. Reputations can be destroyed and fortunes ruined by its findings. A final, highly choreographed public board meeting then takes place at which, with the assistance of the appropriate party chairmen or staff specialists, the investigator-in-charge introduces the significant evidence. The board then adopts the probable cause and publishes its recommendations. Unlike a public hearing, where representatives of the parties may cross-examine witnesses under oath, the parties play no role in the public board meeting, which is unsworn, and where only board members may ask questions.

The investigations and the events covered in this book raised a serious ques• tion mark over the safety of the Boeing 737, the most popular airplane ever built. In February 1990, it eclipsed sales ofthe world's previous best-sellingjet- XIX liner, the Boeing 727, which had totaled 1,832 copies delivered. By March 1999, more than 3,000 Boeing 737s were in service worldwide, having accumulated 91 million hours in the air and carried almost 6 billion passengers-nearly the equivalent of the entire world's population. Hundreds more are on order, and more than 800 are in the air at any given moment around the world. Yet at one stage, investigators privately debated calling for the airplane to be grounded, a call that was made more publicly by one aviation attomey. Had it been heeded, the nation's air transport system would have almost ground to astandstill so vital is the 737 to the system. At least one major airline, Southwest, would have gone out of business because it operates no other air• plane. The FAA was so concerned with revelations about the 737 that it con• ducted its own independent but ultimately inconclusive investigation, separate to the NTSB's long-running probe. During these various probes, sev• eral alterations were ordered to the airplane's controls, additional mainte• nance checks were slated, and pilots had to be trained in special recovery techniques unique to the 737 should they lose control of their aircraft. Even after the NTSB finally announced its dramatic conclusions, a further, more intensive probe by the FAA uncovered more flaws in the airplane. Thousands of 737 aircraft flying today remain under a cloud and will eventually have to be recalled for even further special modifications to make them safer. The extra work needed on the 737 fleet is ironic because, despite its flaws, it has a reasonably good safety record. The NTSB published calculations by an aviation loss adjuster for the ten years ending December 1997, which showed that 43 Boeing 737s had been write-offs due to accidents. That worked out at one 737 crash for every 1,010,101 takeoffs, or a serious crash rate of 0.99 per million flights-better than the Boeing 727 (1.19 crashes per million flights) or the unlucky Fokker series of airplanes, which crashed almost twice as much (2.23 times per million flights). However, the analysis suggested that the McDonnell Douglas competition to the 737 was safer. Its closest competitor in terms of size and vintage, the DC-9 series (including the later MD80 variants) had an accident write-off rate of just 0.86 per million flights, a 13-percent improvement on the 737's record. However, a Boeing analysis based on the same figures divided up the 737 fleet between older and newer model variants. This analysis suggested that the older, 737-100 and -200 variants (including Flight 585, which crashed in Colorado Springs) were three times more likely to crash than newer -300 (including Flight 427, which crashed at Pittsburgh), -400, and -500 variants. In the Boeing analysis, the older -100 and -200 series aircraft had a crash rate of 1.5 per million flights, while the newer models crashed just 0.5 times for the same number of departures, an enviable record for any aircraft model. xx But this is more than just the story of how the problems with one airplane model were tracked down and solved. Throughout, we attempt to illustrate how lessons learned in earlier crashes have a bearing on the solution of more recent disasters. This book also highlights the failure of the Federal Aviation Administration to act decisively on behalf of the traveling public. Throughout the 1980s and into the mid-1990s, the FAA allowed Boeing to produce new vari• ants of the 737 according to outdated certification procedures that harked back to the 1960s when, if had been designing a brand-new airplane, tougher, far safer standards would have been applied. Had those stricter standards been applied to subsequent variants of the 737, the crash of Flight 427 probably would not have occurred and 132 men, women, and children would be alive today. How much of those luckless FAA decisions were part of its own honest strategy, and how many were at the behest of aggressive Boeing lobbyists, may never be known.

XXI