By CBS News correspondent Kris Van Cleave and CBSLA

LOS ANGELES (CBSLA) – More questions have arisen after audio obtained by CBS News shows that the pilots of a Delta flight which was forced to make an emergency landing back at Los Angeles International Airport Tuesday told air traffic control the plane would not need to dump fuel, which it subsequently did, in the process sickening dozens of students and staff at several L.A. area schools.

In the audio obtained through Wednesday, the pilot of Shanghai-bound Delta Flight No. 89 can be heard telling LAX air traffic control that the Boeing 777-200 would land without dumping fuel.

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“I can bring you back to LAX immediately or do you need to hold and burn fuel?” an air traffic controller can be heard asking the pilots of flight 89. “You tell me what you need to do.”

“Delta 89, we’re going to go ahead, we’ve got the engine, we’ve got compressor stalls, we’ve got it back under control, we’re going come back to LAX, we are not critical,” the pilot responded adding they would slow to 280 knots and fly at 8,000 feet to avoid terrain. “We’ll turn back into LA.”

“Ok so you don’t need to hold to dump fuel or anything like that?” the controller asked.

“Negative,” the pilot answered, “we’ll be requesting runway 2-5 right.”

L.A. County firefighters treat patients at Park Elementary Avenue School in Cudahy. Jan. 14, 2019. (CBS2)

However, according to Delta, the plane began dropping fuel at an elevation of 8,000 feet and continued at least until it hit the 2,300-foot mark, CBS News reports.

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The FAA confirmed to CBS News it also found that the Delta crew did not tell air traffic control the plane needed to dump fuel. Air crews will typically notify controllers of an emergency and indicate the need to dump fuel. Controllers, in turn, will then direct the plane to an area appropriate for such action.

A leading US airline told CBS News its policy for fuel dumping is to do it above 5,000 at a minimum. Typically, a flight will dump fuel only if the emergency situation demands it and will do so at 8,000 to 10,000 feet or higher, while over water or an unpopulated area.

Just before noon Tuesday, Delta Flight No. 89 bound for Shanghai was forced to turn back and make an emergency landing due to a mechanical issue.

In the process, the jet did an emergency dump of fuel which landed directly on three schools, including Park Elementary Avenue School in Cudahy and San Gabriel Avenue Elementary and Tweedy Elementary in South Gate. About 20 more L.A. Unified School District campuses were also impacted. Dozens of students and teachers got jet fuel on their clothes, face and arms.

Park Avenue Elementary took the brunt of the fuel hit, with 31 patients treated there. Six were treated at Tweedy and another six at San Gabriel, according to the L.A. County Fire Department.

No one required transport to a hospital. All the impacted schools were open and operating normally Wednesday.

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At a joint news conference Wednesday morning with LAUSD, a Delta spokesperson declined to comment on the investigation.