June 30, 2008
Japan-Bound Airliner Lands Safely in Chicago After Dumping Jet Fuel Over Lake
CHICAGO _ A Japan-bound commercial airliner landed safely at O'Hare International Airport Monday afternoon after one of its engines malfunctioned over the northwest suburbs _ but not before it had to dump fuel over Lake Michigan in order to land.
The right engine on the All Nippon Airways Boeing 777-300ER became inoperable from "metal fatigue" as it climbed over Mt. Prospect about 11:30 a.m., said Elizabeth Isham Cory, a spokeswoman for the Federal Aviation Administration. Earlier, it was thought the engine "may have ingested some birds," she said. The exact cause was under investigation and may take weeks to determine.To make the half-million-pound jetliner light enough to land safely, the pilot swung over the lake and dumped about 1,450 gallons of jet fuel, which raised environmental questions and subsequently sparked monitoring by Chicago water quality managers and beach officials.
QUESTION: Why did the plane dump fuel?
ANSWER: Long-haul airliners always take off with more weight than they are designed to safely land with, and the most readily available source of expendable ballast weight is in the fuel tanks.
Q: Did the pilot dump all of the plane's fuel? And why in the lake?
A: No. The Boeing 777-300ER (The "-ER" stands for "extended range") can travel 9,100 miles thanks to a fuel tank that hauls up to 47,890 gallons of jet fuel. The flight to Japan Monday took off with 34,400 gallons, the airline said.
FAA policy requires the fuel to be dumped in the nearest unpopulated area, in Chicago's case, Lake Michigan.
Q: Does it happen often?
A: Not really. Pilots only need to dump fuel if they are forced to land shortly after takeoff and haven't had time to burn off the fuel in flight, an event usually prompted by a sick passenger or mechanical failure on ascent.
Q: How much of the dumped fuel landed in the lake?
A: About 2 percent or less, based on studies by the Air Force, the FAA and environmental watchdogs. When fuel is dumped above 5,000 feet, in temperatures above freezing, about 98 percent of it can be expected to evaporate before hitting the ground, Isham Cory said. In this case, that would leave about 32 gallons, all of it in widely dispersed fuel droplets.
Q: What happens to it then?
A: The small amount of fuel that settles across the water likely will disappear by the end of the week. Several processes break down the fuel, including sunlight, wind and bacteria that consume the chemicals, said April Markiewicz, associate director of the Institute of Environmental Toxicology at Western Washington University in Bellingham, Wash. From there, it serves as food for certain bacteria, Markiewicz said.
Already present in the Great Lakes, the bacteria necessary to biodegrade the jet fuel will reproduce rapidly in the spill area. (In the absence of a fuel spill, the bacteria normally feed on naturally occurring hydrocarbons such as those in pine trees.)
Q: Is anyone keeping an eye on fuel in the lake, just in case?
A: The Chicago Park District and city Department of Water Management are both monitoring the lake for possible aftereffects, and for different reasons.
Water management officials want to be sure none of the fuel (it is lighter than water) finds its way into municipal water intake lines that supply drinking water to Chicago and 126 suburbs.
The Park District wants to ensure none of it builds up on Chicago's beaches, which, given the math, seems unlikely.
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