A Delta Air Lines pilot was roughly five minutes into a flight from Los Angeles International Airport to Shanghai on Tuesday when he radioed the control tower that he was having problems with the right engine on the jetliner.

A controller asks whether he needs to return to the airport immediately or to “hold to burn fuel.” The pilot responds that they’ve “got it back under control,” will slow down, stay out of terrain and turn back to the airport.

“OK, so you don’t need to hold to dump fuel or anything like that?” he asks the pilot. The pilot responds: “Negative.”

Yet less than 20 minutes later the jet, flying at about 2,300 feet, dumped fuel over Park Avenue Elementary School in Cudahy, dousing children on the playground and sparking outrage in a community that’s been at the center of environmental injustices for decades in Los Angeles County. Dozens of people — many of them children — were treated by paramedics, but no one was seriously injured.

The Times analyzed more than 300 flight paths of Delta flight 89 over the last year provided by Flightradar24, a firm that specializes in maintaining and publishing detailed industry data worldwide. According to the flight-mapping data, the pilot had been on one of two typical routes that Delta flies to Shanghai when he turned back toward L.A. One path takes jets farther west over the Pacific Ocean, while the other turns north over Malibu and the Santa Monica Mountains before veering west. In tracking Tuesday’s flight, the pilot appeared to be taking the latter route and was already over land when he seemed to divert from the expected course above Hidden Hills.

The radio transmissions between the pilot and air traffic controllers raise new questions about why the pilot showered fuel over such a large swath of populated neighborhoods. Federal regulators have said fuel dumping should occur in remote areas. And while the plane was within Federal Aviation Administration guidelines when it dropped the fuel, experts have said the best practice is to discharge at a higher elevation so that fuel dissipates before it hits the ground.

During emergency situations, air crews will typically notify air traffic control and indicate they need to dump fuel. The controllers will then direct a plane to the appropriate fuel-dumping area. This did not happen during Tuesday’s brief flight, according to officials with FAA, which is investigating the incident.

When pilots dump fuel, they typically try to do so above 10,000 feet and over a body of water, such as an ocean, where the fuel will turn to mist and dissipate, away from populated areas, experts say.

Aircraft maker Boeing says if fuel is dumped at an altitude of higher than 5,000 feet, it should turn to vapor before reaching the ground.

“In this emergency situation, the fuel-dumping procedure did not occur at an optimal altitude that would have allowed the fuel to atomize properly,” the FAA said in a statement.

However, FAA regulations do allow dumps at lower altitudes — at least 2,000 feet higher than anything on the ground within five miles, the agency said.

Delta spokesperson Adrian Gee said Tuesday the pilot was forced to dump fuel over an urban area to reduce the plane’s weight before the return landing. It was not immediately clear how much fuel was dropped or what happened between the pilot’s last public communications with air traffic control and the time he landed at the airport at 11:56 a.m.

Delta did not respond Wednesday to a request from The Times for further information.

Ross Aimer, CEO of Aero Consulting Experts, said fuel dumping is very rare and is used only in case of emergencies or if pilots have to reach a safe landing weight.

“Most pilots choose not to dump fuel unless the emergency really dictates it,” Aimer said.

In Tuesday’s incident, the plane was experiencing a compressor stall, according to transmissions between the pilot and the airport tower as well as a radio call the Los Angeles Fire Department received at 11:47 a.m.

“We have a Boeing triple 7, call sign Delta 89, reporting a compressor stall, 181 souls on board, 12 hours of fuel, ETA less than five minutes,” an LAFD firefighter said.

When the compressor of a plane’s engine stalls, it can cause a loss of airflow through an engine, which can cause the engine to fail.

However, compressor stalls are relatively common and aren’t typically considered a dire emergency that would necessitate an immediate landing, according to safety expert and aviation consultant Robert Ditchey.

The Boeing 777 is ETOPS-certified, an acronym used in aviation signifying “extended operations,” which means the two-engine aircraft can fly an extended duration on one engine, Ditchey said. That would suggest there was no immediate urgency to land, he said, per Boeing and FAA standards.

Still, the decision to return to LAX prompted the question from the control tower about dumping fuel. Whether the instruction to release the fuel came from air traffic control or Delta, the ultimate decision-maker would be the pilot, who would have been aware he was flying over a residential area rather than the ocean or other unpopulated area, Ditchey said.

“Dumping is literally a toggle switch. How much fuel you dump is a decision that the captain or Delta Airlines Operations Control would discuss,” he said.

At one point in the audio communications, the pilot tells ground control that 181 people, including crew members, are aboard the plane. According to Seat Guru, a site that tracks the layout of planes, that number would have meant the flight was about two-thirds full.

If that was the case, Ditchey said, it would suggest that a decrease in weight would not have been a major issue because the plane was not at maximum capacity.

The fuel dump has raised concerns about environmental safety in the flight path over Cudahy and other cities.

“Sadly, our entire community has been adversely impacted by this incident, including dozens of children. I am calling for a full federal investigation into the matter, and expect full accountability from responsible parties,” Cudahy City Council Member Jack Guerrero said.

Times Staff Writers Ruben Vives and Samantha Masunaga contributed to this report.

Six candidates, one stage, just a handful of tickets out of Iowa.

The Democratic debate in the Hawkeye State, which serves for the next three weeks as the center of the political universe, marked the seventh round of candidate clashes and the first of the new year.

It had the fewest participants and could prove the most consequential — though it was arguably the most soporific — as it came a scant 20 days before the first ballots of the marathon campaign are cast.

Previous debates provided a few memorable moments, but otherwise did little to recast the contest, which for now appears to be a four-way fight among former Vice President Joe Biden, former South Bend., Ind., Mayor Pete Buttigieg and Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts. Polls suggest half or more of potential caucusgoers are still making up their minds, which further heightened the stakes Tuesday night.

History, for what it’s worth, suggests the outcome on Feb. 3 in Iowa will have a considerable impact on the nominating fight going forward. Typically, only three or so candidates advance from the caucuses as viable contenders.

Here are five takeaways from the mostly low-key debate at Des Moines’ snow-crusted Drake University.

Still chums?

Sanders and Warren genuinely liked each other and, up until just a few days ago, adhered to a mutually agreed-upon nondisparagement pact, even as they competed for many of the same left-leaning voters. But a political campaign can sorely test a friendship, especially when pals are seeking the same office.

The entente seemingly ended over the weekend when Politico reported that volunteers for Sanders’ campaign were given a script bad-mouthing Warren. The two then spent Monday disagreeing over whether Sanders had told Warren in a private December 2018 meeting that, in his view, a woman can’t win the White House against President Trump. He insisted he had not.

Given a chance to continue their dispute before a national audience, the two largely declined.

“I am not here to fight with Bernie,” Warren said, neither backing off nor pressing her assertion that Sanders was fudging about the content of their closed-door chat.

Sanders insisted that of course a woman can be elected and again denied ever saying the contrary. (Warren responded with a classic double-take.)

“Does anybody in their right mind” doubt that a woman can win, Sanders demanded, noting his 2016 rival, Hillary Clinton, carried the popular vote against Donald Trump. (She lost in the electoral college.)

Once the debate ended, Warren declined to shake Sanders’ hand and the two engaged in a brief but animated discussion. The content of that conversation instantly became another subject of speculation.

Happy Joe

Looking on, as Warren and Sanders kind-of-but-didn’t-really tangle, Biden had good reason to flash that Cheshire Cat grin of his.

There is a long history of murder-suicide in politics, to wit: Candidate A attacks Candidate B and voters, disgusted with both, turn instead to Candidate C.

It happened in Iowa in 2004, the race that most closely resembles the current Democratic contest, with its focus on perceived electability and a national front-runner regarded by many in the party with more resignation than enthusiasm.

In that instance it was Vermont Gov. Howard Dean and Missouri Rep. Dick Gephardt, running neck-and-neck in Iowa, who set a torch to themselves, allowing the seemingly dead-and-buried Massachusetts Sen. John Kerry to surge to victory and, ultimately, the nomination.

Of course, no two campaigns are alike and past performance is no guarantee of future results.

Still, any tensions between Warren and Sanders — as well as among their allies and supporters — could well redound to the benefit of others, chief among them Biden.

Iraq, again

Talk about endless wars.

The U.S. conflict with Iraq began in March 2003 and ended, at least officially, in December 2011.

But the political skirmishing over the invasion started long before and continues to this day; indeed, the war — or, more specifically, support for the war — has been an issue in every Democratic presidential campaign that has taken place since, save for 2012, when President Obama was unopposed for the party nomination.

This time, it is Sanders and Buttigieg who have seized on Biden’s October 2002 vote authorizing the use of force — predicated on the erroneous belief that Baghdad possessed weapons of mass destruction — to question his judgment. The “worst foreign policy blunder” of modern times, Sanders called it.

“It was a mistake,” Biden said, as he has before, then noted that once he became vice president under Obama — who had opposed the invasion — “he turned to me and asked me to end that war.”

In the last several days the conflict gained new salience with the U.S. killing of a top Iranian general, followed by retaliatory missile strikes on U.S. forces in Iraq. What remains to be seen is whether the finger-pointing and blame-laying, so far removed from a 17-year-old congressional vote, still matters to any but the most ardently anti-war Democrat.

Klobmentum?

If flattering reviews and positive prognostications translated into actual support, Minnesota Sen. Amy Klobuchar might be running away with the nomination.

She has repeatedly drawn favorable post-debate reviews and assertions from the supposed cognoscenti that this could be her breakout performance. So far, however, the meteoric moment has failed to materialize.

Will this time be any different?

On Tuesday night, Klobuchar was direct, detailed and concise. She was aggressive in pressing her points, without seeming obnoxious. She challenged Sanders and Warren over their advocacy of “Medicare for all” — you need “a plan and not a pipe dream” — aligning herself with the many who fret about losing their coverage and firmly staking herself to the political middle ground alongside Biden and Buttigieg.

She made several references to Iowa and Iowans, an always-welcome nod to local sensibilities. “These are real people hurt by Donald Trump’s trade war,” Klobuchar said in response to a question about trade.

No candidate has more riding on the caucuses; if Klobuchar fails to score in Iowa, where she enjoys special status as a next-door neighbor, it’s hard to see where she climbs into contention.

Steyer’s money’s worth

Tom Steyer has spent more than $100 million on ads promoting his candidacy and, while there is little evidence the former hedge fund executive is a serious contender for the nomination, his weighty wallet has procured him a spot in the last four debates.

(Former New York City Mayor Michael R. Bloomberg, whose Niagara of cash makes Steyer’s investment seem like a trickle, has not bothered to chase the requisite number of donors needed to qualify.)

Although Steyer disappeared for long stretches of the debate, he noted that he’d pushed for impeachment long before most other Democrats came around, and asserted himself by repeatedly invoking his signature issue, climate change. He pointed out he was the only candidate on the stage who had made the fight against global warming his No. 1 priority, and said he would declare a national emergency on his first day in office.

“I cannot allow this country to go down the path of climate destruction,” said Steyer, who has spent tens of millions of dollars, apart from his presidential campaign, to elevate climate change as a political issue.

Still, there was no reason to believe he transformed himself overnight into a top-tier candidate.

For those who despair at the outsized influence of campaign cash, the billionaire’s lagging performance in the race shows that money can’t buy you everything.