On the afternoon of July 19, 1989, United Airlines Flight 232 was cruising high above the American heartland at a ground speed of 560 mph when its tail-section engine suffered an uncontained failure caused by “[t]he separation, fragmentation, and forceful discharge of … fan rotor assembly parts,” which resulted in the loss of the three hydraulic systems that powered the flight controls. The National Transportation Safety Board’s accident report explains how dire the situation was for the 296 people aboard, among them 52 children, who were taking advantage of a United promotion where kids accompanied by an adult could fly for one cent:
“The three independent, continuously operating hydraulic systems are intended to provide power for the full of operation and control of the airplane…. System integrity of at least one hydraulic system is required … for continued flight and landing; there are no provisions for reverting to manual flight control inputs.”
The suddenly crippled McDonnell Douglas DC-10 would have plummeted to the ground within a minute or two had it not been for Captain Alfred Clair Haynes, who reflexively began using “asymmetric thrust” to execute a white-knuckle and largely uncontrolled descent of the 185-ton plane. Ultimately, the ordeal ended with a fiery crash-landing on runway 22 at Sioux Gateway Airport in Sioux City, Iowa, which resulted in the loss of 112 lives, including 11 children. Yet the outcome could have been worse. The NTSB later concluded that “the UAL flight crew performance was highly commendable and greatly exceeded reasonable expectations.”
In the following Failure Interview, Laurence Gonzales, a commercial pilot and author of the new book “Flight 232: A Story of Disaster and Survival” (W.W. Norton), looks back at the cause of the crash, and relates how the accident helped usher in a new era in aviation disaster-response.
Take me back to July 19, 1989. What happened that day at 37,000 feet?
Flight 232 was cruising along on a beautiful midsummer day when the number two engine of the DC-10—the one that runs through the tail—exploded so violently that the bang was heard by farmers on the ground, who looked up and saw pieces falling off the plane. Some of those pieces—coming out at better than the speed of sound—went through the tail and cut the hydraulic lines. Initially, the crew didn’t know anything about this development. They just heard a bang and realized the engine had failed. So they said to the passengers: We lost our number two engine but we have two others, and we can continue on to Chicago. But very quickly the crew recognized that the plane was rolling to the right and rolling past 38 degrees. The plane was about to go over on its back and dive into the ground. At that moment Captain Haynes advanced the right engine to full throttle and retarded the left engine to idle, at which point the right wing started to come back up. By that point the crew knew that something really drastic had happened, and that they could possibly keep the plane upright using the throttles.
Why did all the hydraulics go out?
Each of the three [General Electric CF6-6] engines has two hydraulic pumps, which power the hydraulic system. When the number two engine exploded, it blew those pumps off, knocking out one hydraulic system. When the shrapnel went through the tail it cut the other hydraulic lines because the DC-10 had a design flaw in that the lines were too close together and not shielded.
McDonnell Douglas and General Electric knew that the fan disks on the engine could fly apart, so why wasn’t more attention paid to shielding the hydraulic lines—knowing that all the lines go through one location where there’s a single point of failure?
I haven’t gotten a satisfactory answer to that question. I don’t want to sound cynical, but it all comes down to money. Basically, General Electric and McDonnell Douglas assured the FAA that the chances of this happening were so remote that you could go through the entire life of all DC-10’s in the entire fleet and never have this happen. That was not the case. But it was a gentleman’s agreement among people in the airline industry.
Yes, and I asked Captain Haynes, “How did you get to that runway?” He said, “I have no idea.” He said he expected to roll out of that last turn and land in a corn field somewhere—at best. If you go to flight232.com and listen to the audio tapes, right near the end when he is on final approach he is so excited when he sees the runway. He can’t believe it.
Based on the interviews you conducted with survivors, did the child survivors respond differently than those who were adults at the time of the accident?
The children suffered more emotionally in the long-term. They told me it stole their childhoods. They had grown up thinking the world was safe and suddenly it was revealed to them it wasn’t. So they experienced a sudden loss of innocence that left emotional scars.
In what ways did Flight 232 change disaster response for mass-casualty events?
Although Woodbury County, home of Sioux City, did a very good job of preparing and had a disaster plan that involved an emergency response from all the surrounding communities, they had to go scrounging around the countryside to find the necessary materials to turn one of the hangars into a morgue. They had to go to one place to get an x-ray machine and another to get a dental x-ray machine; they had to get gurneys from all over the county and had to figure out how to keep track of all the deceased people.
Learning from that lesson, there is now a system where there are warehouses on the east and west coast from which a [Disaster Mortuary Operational Response] team can launch a disaster response with Disaster Portable Morgue Units—a portable morgue in a box, which comes with everything you need to process dead bodies. And there’s a list of people who are ready to volunteer to show up to do everything from forensic dentistry to record keeping to accident analysis. So today there is a more organized and systematic way of dealing with disasters.
How did the two United Airlines accidents that occurred in 1989 usher in a more cooperative relationship between the NTSB and the airlines?
Until Flight 811 on February 24, 1989 [when a United 747 suffered an explosive decompression at 22,000 feet, causing nine passengers to be ejected from the airplane], United hadn’t had an accident in ten years. United recognized that their crisis plan was out of date and decided that they would cooperate with the NTSB and work with them, which was new, because the airlines had long regarded the NTSB as the enemy. Second, they decided to talk to the public frankly about what was going on and [communicate the message]: Yes, we had an accident but we’re still a safe airline. It used to be if an airline had a crash they would paint over the logo on any parts of the plane that were visible so the press couldn’t photograph it. United pioneered the end of that era.