Jet fuel rained down from the sky in Los Angeles on Tuesday when an airplane making an emergency landing dumped its fuel over schools, playgrounds and homes.
Emergency medical workers treated about 60 adults and children for minor injuries such as skin irritation and breathing problems at six schools, though all of the patients declined to be transported to a hospital.
The plane, Delta Flight 89, was carrying 164 people and enough fuel to reach its intended destination of Shanghai, when it experienced engine trouble shortly after taking off from Los Angeles International Airport, a Delta spokeswoman said. The pilot quickly sought to return the jet, a Boeing 777-200, to the runway.
The Federal Aviation Administration is investigating the fuel dump, which fell on a five-mile swath in the Los Angeles area, including on a school playground where children were playing, officials said.
The episode raised questions about why the plane would be emptying its tanks over a populated area. Here are some answers.
Why do airplanes dump fuel?
If an airplane is overweight as it approaches the tarmac, it can be harder for pilots to maneuver the aircraft and to slow it down, and a rough landing could even blow out the plane’s tires.
For that reason, passenger planes generally need to be much lighter when they land than when they take off — sometimes more than 100,000 pounds lighter. Ideally, the plane would burn enough fuel during its trip to arrive at the destination airport easily underweight.
But when a plane has to make an emergency landing, either by returning to its departure airport or diverting to a nearby runway, it may not have yet burned enough jet fuel to properly lower its weight.
To solve this, pilots can either circle the plane to burn off fuel or, in an emergency, quickly spray fuel into the air from nozzles on the plane’s wings.
If the plane is high enough — at least 5,000 feet above the ground — the jettisoned fuel will turn to vapor before reaching the ground, according to Boeing. Federal regulations do allow dumps at lower altitudes: The F.A.A. instructs air traffic controllers to assign planes dumping fuel to an altitude at least 2,000 feet higher than anything on the ground within five miles.
Why did Delta Flight 89 drop fuel over schools?
Aviation experts said it is always best to drop fuel from a higher altitude or over the sea rather than neighborhoods and schools. But the experts said the flight crew most likely decided that it was necessary to land the plane as soon as possible and took the quickest route, dumping fuel along the way.
“Every pound they could get off the airplane gave them a little more margin of safety,” said Brad Wheeler, a commercial pilot since 1979 who flew the Boeing 777 for 13 years.
The Aviation Herald reported that the plane had experienced engine compressor stalls on the right-side engine. Mr. Wheeler and other observers said that if the crew had believed the plane was in immediate danger, they probably made the right call, although they might have to justify their decision to regulators.
Plane crews usually tell air traffic control workers when they need to dump fuel so that the controllers can direct them to an appropriate area, but the F.A.A. said on Wednesday that the flight crew never indicated that they needed to empty their tanks.
“It’s an awful shame that children had kerosene rain down on them, but I can see it both ways,” Mr. Wheeler said. “Their objective was to get the airplane safely on the ground and not have anyone seriously hurt or worse.”
Why are some residents outraged?
Though no one was seriously injured by the jet fuel dump, it was a frightening episode for the parents of students at the five elementary schools and one high school where the fuel landed.
At Park Avenue Elementary School, in Cudahy in southeast Los Angeles County, 20 children and 11 adults were treated for minor injuries. But the fuel dump felt like another injustice for some residents of the community.
The Los Angeles Times reported that the same elementary school was closed for more than eight months in 1989 and 1990 when an odd substance oozed up from underground, leading to the discovery that the school had been built on a former city dump.
“The very same playground experienced another environmental injustice,” said Elizabeth Alcantar, who was recently appointed mayor of Cudahy. “For our residents, they’re rightfully upset, and there is concern over when this will truly be over.”
The City of Cudahy plans to host a town hall on Friday to discuss the fuel dump. Ms. Alcantar said some parents were concerned about long-term effects on their children and what they viewed as a disregard for their city. She said she was grateful that the F.A.A. was investigating the dump.
“We want to see that investigation to come to fruition and know why this happened in our community in Caduhy,” she said.