Flight 232: A Story of Disaster and Survival (39 page)

Now he needed to use mathematics and the laws of physics to account for all the forces on the parts of the fan disk and to predict where those parts went. “I remember getting various parts and pieces,” he said. As the pieces came in, Clark kept records and plotted those fragments on maps of the farmland. Working at a long table in a conference room at the convention center in downtown Sioux City, he began by calculating the trajectory from the approximate spot where the engine blew to the locations where the pieces that they had in hand had landed. Such recovered parts yielded a lot of information. They showed the real-world behavior of parts of given shapes, sizes, and masses. Each time Clark calculated the trajectory for another part, it added to his store of knowledge about how those big pieces of the fan disk might have returned to earth. He adjusted other calculations accordingly, even while he consulted with the GE engineers, who were as eager as he was to find the fan disk.

Clark went out to the fields where the parts had been found and used the services of Laura Levy with her laser transit to assign an exact location to each part. Then he returned to the conference room and again sat at his table spread with papers to solve trajectory analysis equations. It was pretty straightforward for someone versed in mathematics and ballistics. Gravity was trying to pull the piece down. The speed of the airplane imparted momentum to the piece, pushing it forward as it was released in the explosion. The pressure of the air against the piece, known as drag, acted to slow its forward motion as it accelerated downward. “And you just keep making repetitive calculations at various time increments,” Clark said. As gravity accelerated the piece toward the ground, the drag increased, thereby reducing its acceleration. Within a few seconds of free fall, the weight of the piece would come into equilibrium with the drag, and the speed at which it was falling would stabilize and remain constant for the rest of the trip to the ground. Once drag had stopped the forward momentum, the piece would drop more or less straight down, except for the motion of drifting with the wind.

“What we’ve found over the years,” Clark said, “is that it’s best to put everything together that you think you know, do your calculations, and find that spot. You can walk right out and put your foot down right on that spot, and then start expanding your search from that point.”

At the time of the explosion, the plane had been moving eastward at a groundspeed of 560 miles an hour. If the plane had dropped a bomb, it would have been easy to calculate where it fell using the speed of the plane and the speed of the wind. But this was more complicated. As the fan disk broke apart and came out of the engine, the pieces could have gone in almost any direction at speeds of almost four hundred miles an hour. In addition, the plane’s forward velocity would have thrown the pieces toward the east.

Clark called his boss in Washington. Monty Montgomery also happened to be the chief of the Engineering Services Division of the NTSB and was an expert in computers and flight data recorders. “Monty,” Clark said, “wrote code for me when I arrived at the Board. He wrote the basic program for trajectory calculations and plotting in Fortran. I modified the basic programs for each accident, customized if you will. I would call him with my new estimates, and he would run the programs to get the trajectory calculations. He would call me with the numbers and I would plot them on a large area map—county crop maps.” Clark’s mapping of the debris that had already been collected matched the ballistic calculations. Those calculations showed where they would expect the missing parts, both light and heavy, to fall.

Another factor Clark had to consider was what might be called the Frisbee effect. Even if the disk still had blades or broken blades attached to it, and even if the disk was fractured and missing a large segment, it might fly, given the tremendous speed at which it was traveling. It might not fly elegantly, but if it produced even a small amount of lift in its spinning descent, it could, Clark calculated, travel more than three and a half miles off of a ballistic, bomblike trajectory during the seven-mile fall to the ground.

Clark had other unknowns to ponder. How would such a titanium Frisbee, possibly weighing in the neighborhood of three hundred pounds, orient itself while falling? Would it approach the earth edge-on like a coin going into a slot? Would it dish out onto its flat side the way a space capsule enters the atmosphere? What happens if you drop a paper plate from a balcony? What if you sail it instead? “Is it flying pointed end first or flat side into the wind or whatever, and that changes your drag characteristics,” Clark said.

By the Friday after the crash, he said, “radar data started coming in, so that pinpointed us down pretty close to where the event occurred. Then I started getting [information] in from the flight data recorder, and with that I knew exactly at the moment when the engine blew, and then I could marry that up with the recorded radar data and get a very precise position over the ground where the engine let go.” The fan disk and other parts had separated in pieces large enough to reflect a radar signal, and Clark could see the parts coming off at thirty-seven thousand feet. If he had his scope set up for it, James Michael Rohde, the air traffic controller at Minneapolis Center in Farmington, Minnesota, might have seen the dark images fluttering down his screen beginning at thirteen seconds after 3:16 on that Wednesday afternoon.

Clark performed some calculations and called Monty Montgomery again to feed him the data. The computer run showed that parts of the fan disk had most likely fallen to earth in either section seven or section eight of Scott Township in Buena Vista County, roughly between Rembrandt and Truesdale, two towns with a combined population of 419 people at the time. The two sections of farmland were each a mile square, but taking other factors into account, such as the Frisbee effect, Clark set the boundaries of the area to be searched, including those two sections, at eighteen square miles. Although Clark would give it an honest try on more than one occasion in the coming weeks, not all the people in Scott Township could have searched an area that large. But Clark hoped to get lucky. On Saturday he recruited the Iowa Public Service Bell JetRanger helicopter. Guided by Clark’s calculations of the areas they needed to search, the pilot flew slowly back and forth about thirty feet above the ground. Clark stared down at the corn blowing this way and that in great sweeps of downwash from the rotors.
*
He could occasionally see the ground between the rows, but he was also aware of the blind spot beneath the helicopter and the ease with which he could miss something that was probably at least partly buried in the Cannisteo and Nicollet and Clarion loams of those fertile fields. Throughout that Saturday, he scanned sections four through nine in Scott Township without results. In addition, Clark understood that the disk could have landed in a pond and might never be found.

That Saturday, the Air National Guard at Lincoln, Nebraska, sent out its RF-4 Phantom fighter planes to take infrared and black-and-white photographs along the flight path that United Flight 232 followed. They used both vertical and oblique cameras, but only the ones looking straight down could see anything on the ground. Most people have never seen an F-4 up close. The planes are huge, and they are extremely loud. By all accounts, those RF-4C missions scared the daylights out of every living thing for miles around, especially people who were already nervous about the crash. The Southern Hills Mall, where Greg Clapper’s wife and daughters saw
Peter Pan,
was deserted the day after the crash because people had heard that 1819 Uniform had flown right over it.

That night, teams of analysts and photo interpreters at the 155th Tactical Reconnaissance Group in Lincoln pored over those recon photos until dawn, trying to identify anything on the ground that might have been made of metal. In the morning, they gave Clark the maps they had drawn and directions to the targets they had identified as promising.

Sunday morning bright and early, John Clark, Edward Wizniak, Laura Levy, and Jim Walker, along with pilots, crew chiefs, and nine other volunteers from the 185th, stood out on the ramp ready to board the Hueys that were parked there on loan from Army National Guard bases in Boone and Waterloo. (Huey is the nickname for the Bell UH-1 Iroquois utility helicopter that was used during the war in Vietnam.) The volunteers and investigators boarded for the short flight out to the area around Rembrandt and Truesdale, and as Walker put it, “It seemed like we landed wherever we needed to, and I’m not sure how the farmers felt about that.” As soon as the helicopters dropped them off, Walker and the other volunteers formed lines and began walking up and down section twelve on the eastern edge of Elk Township, which was the area adjacent to and west of section seven, where Clark thought the fan disk might have fallen. Walker was not prepared for the conditions that day. The corn was pollinating itself, and the air was thick with the yellow dust. “I have hay fever,” he said, and after several hours of searching, “I couldn’t even breathe, and somebody took pity on me, and when it was time to go home, I got to ride in the air-conditioned Bell helicopter with the leather seats.”

John Clark said, “On one of the searches, Laura Levy and I had been out most of the morning, and it was hot with no wind. The corn pollen was really bad, and the corn was over my head. We stopped at a gas station on a section corner, out in the middle of nowhere, it seemed. Laura needed some water to rinse out her eyes. Her contacts were giving her fits. We went in and there were a number of gents sitting around. They went outside to the pitcher pump, and with a few pumps we had all the well water we needed.”

Clark and Levy and the others were attempting to follow the directions from the photo interpreters, who had provided maps of suspected metal objects. The work was frustrating and fruitless. Clark would usually find something, but never what he was looking for. Often the team members were chasing shadows. They found pieces of metal. They found a feed sack. One time they found an object that was round and dark and had no corn on it. On the photograph, it looked as if it might be a big disk. When Clark and Levy slogged through the corn, covered in the choking yellow pollen, to reach the spot at last, it turned out to be an anthill. The search turned up nothing of value, but it demonstrated to Clark that the effort required for searching on foot was prohibitively large. Clark and Wizniak rode in the Hueys as they continued to fly up and down, back and forth. The investigators sat in the open doors, wind blowing around them, feet resting on the skids, and watched the corn blow.

Clark did go out to the spot where he had calculated fan disk 00385 to be, and he did put his foot down on the ground there. He didn’t know it that day, but he was only a few hundred yards from the disk 00385. In the vastness of the sea of corn, that amounted to near pinpoint accuracy. But being close to the disk didn’t make the search any easier. He returned to the Hueys and continued staring at the corn flowing past the door. “And I think we probably flew over that part down in that corn twenty, thirty, forty times,” he said.

Through the frustrating days and then weeks after the crash, Clark was groping around for any kind of help he could get. It was essential to locate those parts if the people involved in this event were ever to be certain of what had been done to those passengers and why and by whom. In fact, most of the investigators from the NTSB, the FAA, United, GE, and McDonnell Douglas believed they knew what had happened. But United Airlines, General Electric, McDonnell Douglas—
they had killed 112
of the 296 people on that plane. (Gerald Dobson was not yet dead but soon would be.) They had destroyed countless lives. The investigators could not simply hazard a guess as to what they thought might have happened. They had to compile the best evidence they could find. The people at General Electric wanted to know as badly as anyone. They wanted Clark to find the parts so that this type of accident might never happen again.

While Clark and Wizniak and the GE engineers were searching for the missing fan disk,
John Young, an investigator from the NTSB
, flew to Cincinnati, Ohio, near Evendale, where General Electric made its jet engines. There he worked with GE engineers, who were poring over records. Young was joined by David Cookson from United Airlines, who was in charge of searching and sequestering records for the airline anytime there was an incident or accident. Young and Cookson had had occasion to work together earlier in the year, when United nearly lost another jumbo jet, Flight 811 out of Honolulu, the accident in which nine people died. “We had a bad year that year,” Cookson said. “John Young and I established a pretty good relationship. He was very professional.” While John Clark wanted to know where that fan disk had gone, they wanted to know where it had come from. James W. Tucker, the general manager of Product Operations at GE, an engineering expert in turbines, even traveled to the offices of some vendors to dig through what he called “
their dead letter file
.”

The
records from that period of time at both ALCOA and GE
 were in a fair state of disarray, with some documents missing while others contained outright errors. Young and Cookson, Tucker, Moehring, and others were trying to determine the origin of the metal that was used to make fan disk 00385. In its final report, the NTSB called the records “contradictory” and “deficient.” It said, “The records on a large number of [General Electric] disks are suspect.” The report further stated that “several anomalies appear in the records [of General Electric], which call into question the reliability or accuracy of all the disk records from the same period. For instance, there were no records found indicating receipt of the fan disk forgings by the [General Electric] plant.”

Despite the consistently sloppy practices at General Electric, NTSB investigators came to realize that in 1971, a company called Titanium Metals of America out in Henderson, Nevada, had cast a cylinder of titanium weighing about seven thousand pounds. The missing fan disk had been cut from that column of titanium and then forged by ALCOA and machined by GE into the finished part. Disk 00385 from 1819 Uniform was one of eight that had been made from the same batch of metal. All of those pieces had been tested, and during those tests, one of the disks, not yet finished, had fallen under suspicion of having a defect. It never went into service. The
seven others passed the tests
, and six of them were still flying on DC-10s at the time of the crash.