Delta has tough questions to answer from the FAA about why it dumped jet fuel over a school during an emergency landing at LAX

• The FAA said it was investigating why a Delta flight dumped jet fuel over a residential Los Angeles neighborhood on Tuesday.
• At least 44 children people at several elementary schools, including children, were treated by paramedics after coming into contact with the fuel.
• The Delta flight declared an emergency shortly after take-off from LAX due to an "engine issue," and was returning to the airport.
• Planes dump fuel as an emergency measure to make them light enough to land soon after takeoff.
• However, they are supposed to dump fuel over unpopulated areas, and at high enough altitutde for it to evaporate. Neither happened here, and US regulators want to know why.
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The Federal Aviation Administration said on Tuesday that it is "thoroughly investigating" why a Delta flight dumped jet fuel over a residential neighborhood in Los Angeles.

At least 44 children and adults at several elementary schools near Cudahy, Los Angeles, were affected after the fuel was jettisoned.

The patients mainly suffered skin irritation, and none needed to go to the hospital, the Los Angeles County Fire Department said.

Delta Air Lines flight 89, from LAX to Shanghai, China, declared the emergency after experiencing an unspecified engine issue not long after takeoff.

The flight turned north over the Pacific Ocean immediately after taking off and began to climb, but leveled off north of Calabasas before turning east over Los Angeles to circle around and return to the airport.

The plane then descended steadily before turning for a final approach into the airport, passing over Cudahy at around 2,375 feet, according to data from FlightRadar24.

It was not clear when the plane began dumping fuel, nor how much of the 24 minute flight was spent ejecting fuel, a process that can last a relatively long time.

A statement from the FAA said:

"The FAA is thoroughly investigating the circumstances behind this event. There are special emergency fuel-dumping procedures for aircraft operating into and out of any major US airport.

"These procedures call for fuel to be dumped over designated unpopulated areas, typically at higher altitudes so the fuel atomizes and disperses before it reaches the ground."

Typically, a plane will dump fuel when it needs to return to the airport because of a technical problem or an on-board medical issue.

Larger planes, like the Boeing 777-200 in this case, have fuel dumping capability to reduce landing weight, avoiding damage and possible risks to the plane or runway. Smaller planes will either land "heavy," or fly in a holding pattern to use up fuel before landing.

However, according to the FAA, there are "special emergency fuel-dumping procedures" for planes flying into or out of major US airports.

In most cases, fuel evaporates before reaching the ground.

Procedures call for fuel to be dumped "over designated unpopulated areas," according to the FAA, "typically at higher altitudes so the fuel atomizes and disperses before it reaches the ground."

An aircraft might deviate from those procedures if it isn't possible to get high enough or far enough from populated areas. However, it was unclear whether that was the case with Delta 89.

It was also not immediately clear whether air traffic controllers approved the fuel release over a populated area from low altitudes.

In a statement, Delta called the fuel dumping "normal procedure," but said it had "concerns" over the reported injuries. It said:

"Shortly after takeoff, Flight 89 from LAX to Shanghai experienced an engine issue requiring the aircraft to return quickly to LAX. The aircraft landed safely after a release of fuel, which was required as part of normal procedure to reach a safe landing weight.

"We are in touch with Los Angeles World Airports and the LA County Fire Department and share concerns regarding reported minor injuries to adults and children at a school in the area."