Posted on Tue, Oct. 29, 2002

Crash will put investigators to the test

BY DAVID HANNERS
Pioneer Press

They said you never forget the smell, and they were right.
It is earth saturated with aviation fuel. Almost every crash site has it. NTSB air safety investigators call it simply "the smell of death."
It is one of the first things a National Transportation Safety Board investigator learns to get over as he is "kicking tin," picking through wreckage for an answer to a simple question: Why did this plane crash?
The second thing he learns is that he will rarely, if ever, come up with any quick or easy answers to that question. Some mysteries don't get solved.
Investigators working on NTSB Accident/Incident No. DCA03MA008 - the crash that killed U.S. Sen. Paul Wellstone, his wife, daughter, three campaign workers and two pilots - may face the same uncertainty. There were no survivors to interview. No witnesses saw the crash. The pilots didn't radio for help. The plane lacked a cockpit voice recorder.
In short, there will be some things about this accident we will never know. NTSB investigators have a saying among themselves: When they die, they intend to look up the pilots of accidents they describe in their reports and ask them what really happened.
All accident inquiries follow a standard procedure from the moment the NTSB is notified that a plane is down until the day, many months later, when the five-member board convenes to rule on the probable cause.
In the immediate aftermath of a crash, the public and the media want to know what caused it, and they want to know it now. But aviation accidents aren't that simple to decipher. More often than not, a crash is the end result of a complex series of events. An investigation is usually a matter of finding the links in that chain and putting them together.
Before an NTSB investigator even arrives on the scene, though, the agency's probe has already started. Among other actions, it has ordered the preservation of tape recordings of air traffic control conversations and weather briefings. It has told the owner of the airplane and the companies that built it to collect every record they have on the plane and pilots.
An investigation is broken into eight subgroups: the plane's structure and wreckage; electrical and flight control systems; engines and fuel system; maintenance history; details of the flight and pilot training; the involvement of air traffic control systems; the weather; and "human factors," which include the crew's medical records, whether the accident was survivable and the response of emergency workers.
In the months ahead, much of the probe will be conducted out of the public eye by the likes of metallurgists, meteorologists, computer experts and others. For most people, the field investigation is the public face of the NTSB, and that is where the first clues to the mystery are rounded up.
There is no "average" crash site, but if a generalization can be made, it is that plane crashes are utter chaos filled with twisted pieces of metal just waiting to cut you. (Investigators get regular tetanus shots.) In some accidents, some parts can be identified as having once been part of an airplane; in others, all that remains is a crater filled with metal, bundles of wiring, shards of Plexiglas, bits of plastic, scraps of paper and anything else that wasn't destroyed on impact or incinerated by fire.
And there is that dreadful smell.
Local authorities said the probe into Wellstone's crash will be hampered by the fact the plane came down in a bog. Yes, it will be harder, but the NTSB has pulled planes out of swamps, recovered debris from the ocean floor and picked pieces out of Louisiana bayous. After a 1989 crash that killed a congressman, it even combed through wreckage on a snake-infested mountainside in Ethiopia accessible only by helicopter.
Once at the crash site, the investigator first works to document the "four corners" - the plane's nose, wing tips and tail. Photos are snapped, tape measures are stretched from one point to another and distances are noted on a map.
The four corners can tell an investigator at least a couple of things. It can show what direction the plane was headed. In the case of Wellstone's plane, the finding that the plane was perpendicular to the runway could be a sign the plane was off course. Naturally, that leads to the question: Why was it off course?
Finding the four corners can also tell if the plane was in one piece at impact. If a "corner" is missing, it might indicate the plane broke apart before it crashed.
And if it broke apart, that again raises the question of "why?"
The way various fuel lines burned can reveal if an engine was running at impact. The way the titanium turbine blades inside a jet (or turboprop) are broken, bent, dented or pitted also can tell much about how an engine was operating.
The debris may look like a jumble, but every piece is a potential clue - pieces that investigators refer to as "Easter eggs." Of particular interest are the plane's control surfaces - flaps, ailerons, horizontal stabilizer and rudder - and the jackscrews, hydraulic devices or cables that operate them.
Something that is not much thicker than a human hair can cough up a plane's secrets. For instance, the filaments inside the tiny bulbs that illuminate cockpit instruments are hot and malleable when they are lit, so they stretch at impact.
If the bulb isn't on, though, the filament shatters. Documenting which filaments stretched and which shattered can tell investigators what instruments were working. If every filament is shattered, then it can indicate the plane lost electrical power - meaning the pilot had no instruments - before the crash.
When the on-site probe is done, the wreckage is carted up. In some inquiries, the NTSB rents hangar space to lay out the parts in an attempt to "reconstruct" the plane, and in other cases, it is returned to the owner.
The engines are shipped to the manufacturer, where they are disassembled under NTSB supervision to see if they were running properly at impact.
The eight subgroups submit their findings to the investigator-in-charge, who writes a factual and summary report. Field investigators have a saying that when the weight of their paperwork equals the weight of the wreckage, it's time to write the report.
The summary report makes it through the NTSB bureaucracy and then goes to the five-member board. After a public hearing, the board determines the accident's probable cause, and also makes any safety recommendations it believes are necessary.
But many accident reports wind up being the best guess - using all the available evidence - of the investigators whose job it is to find out why a plane fell from the sky.
"To figure out one of these things," an NTSB investigator once said, "give me someone who is one-quarter engineer, one-quarter pilot, one-quarter psychologist - and one-quarter soothsayer."

David Hanners can be reached at dhanners@pioneerpress.com or (651) 228-5551. Hanners is the only journalist ever allowed by the National Transportation Safety Board to observe an entire air crash investigation from the "inside." He spent 22 months with the NTSB as it sought the cause of an April 1986 crash that killed seven. The resulting article, "Anatomy of an Air Crash: The Final Flight of 50 Sierra Kilo," was awarded the 1989 Pulitzer Prize for Explanatory Journalism.

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