Tellmann and the captain parked the Airbus A319 at the gate. But they had no memory of landing or taxiing Spirit Airlines Flight 708. Tellmann went to the hospital for treatment and spent the next week at home in bed, vomiting and shaking and feeling “like a freight train had run over us,” he said in a letter to his union about the July 2015 event.

A mysterious smell. Strange symptoms. A trip to the emergency room.

The signs were all there: Something had gone seriously wrong with the plane’s air supply.

The air you breathe on airplanes comes directly from the jet engines. Known as bleed air, it is safe, unless there is a mechanical issue — a faulty seal, for instance. When that happens, heated jet engine oil can leak into the air supply, potentially releasing toxic gases into the plane.

For decades, the airline industry and its regulators have known about these incidents — called fume events — and have maintained that they are rare and that the toxic chemical levels are too low to pose serious health risks.

But a Times investigation found that vapors from oil and other fluids seep into planes with alarming frequency across all airlines, at times creating chaos and confusion: Flight attendants vomit and pass out. Passengers struggle to breathe. Children get rushed to hospitals. Pilots reach for oxygen masks or gasp for air from opened cockpit windows.

Such events are documented in airport paramedic records, NASA safety reports, federal aviation records and other filings reviewed by The Times.

Tellmann, the Spirit Airlines pilot, was one of hundreds of airline crew members and passengers who reported being sickened or impaired on flights in recent years. A Times analysis of NASA safety reports from January 2018 to December 2019 identified 362 fume events that airline crew members reported to the agency, with nearly 400 pilots, flight attendants and passengers receiving medical attention. During at least 73 of those flights, pilots used emergency oxygen. Four dozen pilots were described as impaired to the point of being unable to perform their duties.

Because they’re made voluntarily, the NASA safety reports are the “tip of the iceberg,” according to a recent study by a researcher from the National Institute for Occupational Safety and Health.

As millions of holiday travelers ignore public health warnings against flying amid a surge of new COVID-19 cases, airlines are touting their HEPA filters, cleaning practices and other precautions to convince passengers that their planes are safe. But those measures won’t protect you from toxic gases. Neither will surgical masks nor N95 respirators.

Indeed, fume events have continued throughout the pandemic. One week in August, for example, JetBlue Airways had fume events on flights into Boston and Orlando, Fla., federal aviation records show. On a March 26 American Airlines flight to Fort Lauderdale, Fla., all flight attendants used oxygen after cabin fumes left them dizzy and nauseated.

Passengers are often unaware that their air supply has been contaminated. Fume events can be odorless, and some of the most common symptoms of exposure — headaches and fatigue — are indistinguishable from jet lag, experts say. Airlines have no obligation to notify passengers of fume events and have sometimes provided misleading information.

In the era before the coronavirus, about five flights a day in the U.S. experienced a fume event, according to an academic study of aviation records. But no government agency tracks fume events or how often people become sick or impaired.

Pilots and flight attendants have reported an array of health problems, including eye irritation and coughing, as well as more serious long-term conditions: tremors, memory problems, brain damage and other illnesses that have kept them out of work for months and sometimes ended their careers, according to airport and aviation records, workers’ compensation filings, court papers and other documents.

Scientists have long warned of potential dangers from breathing heated jet engine oil, which contains tricresyl phosphate, a highly toxic chemical that can damage the nervous system. Heated oil can also produce carbon monoxide, an acutely incapacitating gas. A 2002 study mandated by Congress recommended requiring carbon monoxide sensors on all passenger airplanes. Today, most homes have them; airplanes do not.

That night Gelber began to feel dizzy, and within a few days he came down with a high fever and a wet cough that lasted a week. Passengers were “breathing smoke for about a half an hour,” said Gelber, who still had a cough months later. A sales manager who travels frequently, Gelber worried about possible long-term health effects from whatever he was exposed to.

The industry’s regulator, the Federal Aviation Administration, declined to comment on The Times’ findings and provided a statement saying it “currently has no plans” to require air sensors or filters.

“Studies have shown cabin air is as good as or better than the air found in offices and homes,” the FAA said.

But those studies looked at normal flights in which no fume events were reported. No major research has ever measured the chemicals in fume events as they occur.

In 2003, Congress ordered the FAA to measure the toxic chemical levels in such events, but the airlines refused to let flight attendants carry air samplers aboard, according to an FAA-funded research report.

The largest union of cabin crews, the Assn. of Flight Attendants, has called for the FAA to take action on fume events for more than 25 years.

“The industry is concerned about liability, and the FAA is protecting the industry,” said Judith Anderson, who works on health and safety issues at the union.

Fume events represent a fraction of the thousands of flights that crisscross the U.S. every day. Often associated with a “dirty socks” smell, their seriousness varies, and many go unreported or cause no apparent health effects.

While federal authorities have never attributed any commercial airplane crashes to fume events, emergency scenarios play out with disturbing frequency, according to interviews with pilots and flight attendants, an analysis of airline reports to the FAA, airport first-aid records, workers’ compensation filings, litigation documents and internal airline maintenance records.

Swipe to see events

Feb. 26, 2019

Alaska Airlines Flight 1506

The flight to Orange County returned to Seattle because fumes in the cockpit made the pilots dizzy and nauseated. The captain had to turn over the airplane’s controls to the copilot to handle the landing while both were wearing oxygen masks, according to airport and NASA reports. Paramedics took the pilots and a flight attendant to the hospital. In his report, the captain noted that it was his third fume event.

‘We collected our bags and followed the paramedics to the gate area where they evaluated us. The three of us all went to the hospital for further evaluation. We all tested positive for high CO [carbon monoxide] levels in our blood.’

Captain's first-person report

March 27, 2019

Spirit Airlines Flight 245

Fumes in the cabin of the Las Vegas-bound flight sent four people to the hospital, airport records show. One passenger lost consciousness and had a seizure, a second was knocked unconscious, and two vomited, according to Spirit’s report to the FAA. The next week, the same plane had another fume event, FAA records show.

April 16, 2019

JetBlue Flight 629

The flight to Puerto Rico returned to Orlando, Fla., after a strong acrid odor filled the plane and passengers complained of itchy eyes and nausea. The pilots “were forced to breath[e] pressurized emergency air in order to escape further exposure,” according to airport records. Two people were taken to the hospital.

June 13, 2019

American Airlines Flight 1380

Noticing fumes shortly after takeoff, the pilots donned their oxygen masks and returned to Newark, N.J., FAA and airport records show. The pilots and flight attendants told paramedics they “had scratchy throats, confusion and felt as though they were drunk.” One had trouble breathing and was breaking out in a rash. The whole crew was taken to the hospital by ambulance. The same plane had two more fume events over the next 11 days, internal maintenance records show.

None of the airlines addressed specific questions about those incidents. Spirit Airlines did not make Tellmann, the pilot on the 2015 flight into Boston, available for an interview. “Our flight crews are trained in odor/fume identification, and Spirit technicians follow strict protocols and use sophisticated scientific equipment,” the airline wrote in a statement. “We believe that we operate with the cleanest air in the industry.”

Tellmann, who has since been promoted to captain, told his story of conking out in the cockpit at a 2016 meeting of American Airlines pilots, according to a video of the event posted by the Aviation Herald. Pilots and flight attendants are getting seriously sick, Tellmann warned, but crew concerns are widely dismissed.

“This is the tobacco and asbestos of aviation,” Tellmann told the pilots.

‘In harm's way’

The passengers were strapped in and ready for takeoff when fumes enveloped Southwest Airlines Flight 3455. The plane taxied back to the gate at William P. Hobby Airport in Houston. The passengers deplaned and were stunned by what they saw next: Both pilots and four flight attendants were being pushed off the plane in wheelchairs.

In a report of the June 2019 event filed with NASA, the captain said he and his copilot became so alarmed by the fumes that they opened the cockpit windows and stuck their heads out to get fresh air. The captain said he felt increasingly confused and “drunk” and had a “difficult time concentrating and formulating thoughts and speech.”

An airport employee who walked down the jetway to meet the Boeing 737 also ended up being treated by paramedics, airport first-aid records show. Ambulances brought the entire crew to a nearby emergency room.

The incident, the captain noted in the report, was a “fumes event.”

Disturbed by the scene, several passengers had asked what they were exposed to. Southwest Airlines told them the smell was rotten jackfruit brought on board by a passenger.

In a statement to The Times, Southwest maintained that fruit was to blame for the incident but would not comment on the captain’s safety report to NASA.

Airlines aren’t required to tell passengers if a fume event has happened or what they might have been exposed to.

The FAA is supposed to track fume events. Congress in 2003 ordered the agency to create a new and comprehensive reporting system. It never did.

What little information is available relies on a reporting system plagued by loopholes and airline noncompliance.

Airlines aren’t required to report sicknesses linked to fume events. And the FAA, for its part, doesn’t collect information about such health problems.

More than a decade ago, the FAA funded a study that would have determined the toxicity of fume events, using air samplers that cost about $250 each. The research had been mandated by Congress. But the airlines refused to allow flight attendants to bring the devices aboard, according to a 2014 FAA-funded report.

“If you want to find out what the exposure is and you don’t allow them to make the measurements, then what is the point?” asked Christiaan van Netten, a toxicologist and a professor emeritus at the University of British Columbia who designed the samplers.

The FAA has repeatedly assured the public that fume events are rare and that the air on planes is superior to the air on the ground. The agency told Congress in 2003 that airlines “have the added benefit of flying at altitudes above the air pollution.”

In recent statements, the agency referenced studies showing “less than 33 [fume] events per million” flights.

But a 2015 study by Kansas State University funded by the FAA concluded that the actual frequency is more than six times higher — about 1 out of every 5,000 flights. A top Boeing official said in a recent deposition that the study’s finding was accurate.

Congress has twice held hearings on plane air quality — in 1994 and 2003. Legislation that would force the industry and regulators to adopt some safety measures has repeatedly languished in committee.

A current effort, the Cabin Air Safety Act, sponsored by Rep. John Garamendi (D-Walnut Grove) and Sen. Richard Blumenthal (D-Conn.), would require carbon monoxide detectors on all commercial planes, as well as mandatory fume event training and reporting. The legislation is all but certain to die in January when the current congressional session ends.

After a group of JetBlue flight attendants called attention to the issue, the two lawmakers wrote a letter to the airline in September 2019, saying it was placing “employees and customers in harm’s way” by exposing people to fumes with “dangerous health effects.”

JetBlue’s vice president of safety, John Allen, responded in a letter that said no one had ever received “unhealthy air” from “perceived odors” on the airline’s flights.

“Myths” were feeding “crewmember angst,” Allen wrote. “Unfortunately, we have found this to be a very emotional issue.”

JetBlue’s public statements contrast with airport first-aid records and airline mechanical reports to the FAA. In 2019, at least 46 people reported symptoms during fume events on JetBlue flights. On more than 50 occasions last year, JetBlue flights were forced to make emergency landings or diversions or return to the gate because of fumes, The Times found.

One JetBlue plane had four fume events in a single week in May 2019, FAA records show.

In September 2019, a JetBlue flight returned to San Juan Airport in Puerto Rico after fumes left crew members nauseated and dizzy. One attendant was so disoriented she was barely able to provide the safety instructions to passengers. Both pilots and three flight attendants were hospitalized, according to an FAA report.

“While cabin odors and fumes are not isolated to JetBlue, we have set out to be an industry leader in understanding these events and identifying policies and procedures to reduce and manage them,” the airline wrote in a statement to The Times. “We would never operate an aircraft if we believed it posed any health or safety risk to our customers and crewmembers.”

At least three JetBlue pilots are currently grounded as a result of injuries they claim are connected to fume events, according to workers’ compensation filings.

In the case of one of the pilots, a workers’ compensation judge in Oregon ruled in July that he had suffered brain damage from toxic chemical exposure in a fume event. In the ruling, which JetBlue has appealed, the judge blasted “the airline industry’s ongoing pattern of obstruction” and efforts “to create plausible deniability.”

“Airlines appear to be more concerned about keeping planes in the air than worker safety,” the judge wrote.

‘Looking for a tombstone’

Five years ago, German airline Lufthansa asked Boeing for a new feature on 777X jets: sensors. Lufthansa believed the air monitoring devices were necessary to detect fume events, according to an internal Boeing memo. Lufthansa, the memo stated, had health concerns about contaminated air and worried about resulting disruptions and extensive maintenance.

Boeing never installed sensors.

The company told The Times that there is “no reliable and accurate real-time sensor for detection of contaminated bleed air validated for use in commercial aircraft.”

Experts say workable sensors probably could have been developed years ago with the proper research and testing. Boeing’s own expert, Auburn University professor emeritus Ruel Overfelt, said in a deposition last year that sensor technology that could be adapted for planes “could probably be bought off the shelf” and had been available for “more than 10 years.”

Air quality in jets has long concerned Boeing. As far back as 1953, an internal study on what Boeing called “the Air Contamination Problem” discussed the need for filters to “purify” cabin air. Boeing warned its own workers in a 2007 safety advisory sheet that engine oil fumes may damage the nervous system and cause symptoms such as “dizziness, headache, confusion and ‘intoxication.’”

Boeing appeared to take a major step in 2001 when it asked suppliers to present sensors capable of alerting crew members within a minute of “compromised air quality conditions,” according to an internal Boeing document.

Honeywell and General Electric responded with proposals. GE’s sensor, a Boeing manager wrote in an email, “appears to be a sound approach.”

But Boeing decided against installing sensors on its planes.

The company’s managers had legal concerns that went beyond technological shortcomings, according to depositions and Boeing internal emails obtained by The Times.

A Boeing senior engineer, George Bates, acknowledged in a 2018 deposition that there were internal concerns that sensors would collect data that could be used by sick passengers or crew members in litigation against Boeing. “The biggest impeding factor is the legal issues,” Bates wrote in a 2008 email.

Bates elaborated in an internal email in 2011: “How long will it take until the readings have to be recorded and available not only for maintenance, but for the lawyers?” he wrote. Another Boeing engineer on the email chain agreed that making sensor data available was “crazy!”

Bates had expressed concern about fume events in the past when he noticed that Boeing 757s were being diverted about once every two weeks. Engine seals, he said, were leaking so much oil that crews complained of “blue smoke” thick enough that flight attendants couldn’t see halfway down the aisle.

“Given the number of … events for the 757 ... I would have thought the FAA would have forced the issue,” Bates wrote in an email to colleagues. “Bottom line is I think we are looking for a tombstone before anyone with any horsepower is going to take interest.”

Bates, who is retired from Boeing, could not be reached for comment.

The company’s internal data counted 823 serious fume events from 1999 to 2013, according to documents filed by flight attendants in a recent lawsuit against Boeing. They were deemed “potential safety issues,” another Boeing engineer said in a deposition.

Boeing did not address specific questions about Bates’ comments or the flight attendants’ claims. “Despite the absence of any credible data showing that rare oil leaks into the bleed air stream can cause serious or permanent injuries, Boeing has also invested in assessments of sensor technologies,” the company wrote in a statement.

Without sensors to measure air quality, Boeing has relied on a low-tech alternative: people’s noses.

Cheryl Bick, a Boeing chemist known for her exceptionally good sense of smell, was often the go-to person when airlines complained about stinky planes. She said she did more than 95 odor investigations during her 16-year career at the company. About 90% turned out to be fumes from engine oil or hydraulic fluid, Bick said.

When she took her equipment on planes to do her tests, Bick said she was not allowed to wear an oxygen mask because it would have made onlookers uneasy.

“I always did it because I wanted to help,” said Bick, who was laid off in 2017. “I wanted to fix planes. I wanted to find out what was making people sick.”

In 2007, Boeing unveiled a new airplane, the 787 Dreamliner.

Among the features of the long-range jet was a new air distribution system. The air in the Dreamliner is funneled into electrical compressors near the wing, rather than through the engines. It is the only commercial jet of its kind to use that technology.

An internal Boeing document detailed one reason for the new design: “Improved air quality” through the “elimination of engine contaminants potentially entering cabin air supply.”

Something in the air

When US Airways Capt. David Hill’s plane took off from the Virgin Islands one day in January 2010, he had no idea it would be his last flight.

A smell had spread through the plane, sickening five flight attendants and leaving Hill and his copilot groggy. Hill called ahead for paramedics, and when he landed in Charlotte, N.C., ambulances and firetrucks were already on the tarmac.

Paramedics took Hill and the rest of the crew to the emergency room with symptoms of dizziness, headaches, breathing difficulties and confusion.

Within a month, Hill couldn’t read an analog clock.

Within six months, Hill received a letter from the FAA ending his three-decade flying career.

“A careful review of your reports ... after your Jan 16, 2010 fume incident on Flight 1041, discloses that you do not meet the medical standards,” the FAA said, referring to health requirements necessary to safely perform the duties of a pilot.

The letter listed dizziness, imbalance and chemical exposure as the reasons for pulling his certificate.

A year later, Hill wrote the FAA, urging it to mandate air filters and sensors. He said his copilot and flight attendants suffered neurological damage and were also unable to work. He questioned why the agency had not informed passengers that they had also been exposed to dangerous chemicals.

This time, the agency took a different stance.

“We have not been able to trace clear cause-and-effect relationships between contaminant exposure and short-term and long-term health effects,” wrote Dorenda Baker, the FAA’s director of aircraft certification.

“I am sorry to hear of your difficulties,” Baker added.

Over the years, the FAA has sent mixed messages on whether fume events are harmful. The agency funded a 2009 medical guide for treating health problems related to fume events. It warns that “neurological, psychiatric, respiratory, systemic, and dermal symptoms … may last for years after the exposure.”

There is scientific consensus that the chemicals in engine oil are highly toxic and can damage the nervous system.

But the industry argues that the levels of those chemicals during fume events are too low to cause health problems. However, no major study has ever tested the chemical levels during fume events or collected data on illnesses.

Scientists have found that oil and hydraulic fluid break down when heated, producing toxic chemicals such as carbon monoxide and formaldehyde, which is classified as a human carcinogen by the Occupational Safety and Health Administration.

Perhaps most troubling is tricresyl phosphate, or TCP, an organophosphate added to engine oil. Doctors and scientific researchers have known that TCP is toxic to the nervous system since the 1930s. Researchers say that extreme heat, such as in a jet engine, makes oil fumes even more toxic to breathe.

TCP can have immediate effects such as headaches and dizziness, as well as longer-term effects such as tremors and memory problems, experts say.

The effects of breathing engine oil fumes vary from one person to the next, said Van Netten, the University of British Columbia toxicologist. “The same goes for the pilots. That’s why one pilot might feel incapacitated and the other pilot is able to keep working.”

Airbus, in a cabin air contamination report form it distributes to airlines, recognizes that air contamination can cause symptoms including fainting and headaches. But the manufacturer also tells its customers that there are “no proven long-term health risks.”

Many people recover from fume-related ailments within days. But some have been diagnosed with life-altering and career-ending health conditions.

Raymond Ottesen, a pilot at a major U.S. airline, said he has been unable to fly since 2016 following exposure to fumes that left him with severe health problems. Pilots “could be incapacitated, and you’re sitting in the back thinking everything is good,” said Ottesen, whose lawsuit against Boeing, filed in 2018, is pending. Boeing denied the claims.

JetBlue Capt. Andrew Myers was parked at the gate at Portland International Airport in Oregon one morning in January 2017 running engine tests before passengers boarded the flight to Long Beach. He was trying to figure out the cause of a foul odor that flight attendants and passengers had complained about the previous day. Suddenly a thick haze and a strong choking smell like dirty socks filled the plane. Myers left the aircraft seeking fresh air and fell down on the jetway coughing, according to workers’ compensation filings.

Before his fume event, Myers, 52, had been training for a triathlon. After the event, he needed a cane to walk, suffered from tremors and struggled to speak, the filings show. At times he couldn’t remember where he was.

A year later Myers received a letter from the FAA pulling his medical certificate due to his “toxic encephalopathy” — brain damage from exposure to toxic chemicals.

In Myers’ workers’ compensation case, JetBlue denied that his injuries were caused by the fumes and hired Richard Pleus, a toxicologist who regularly consults for Boeing and airlines. Pleus testified that the dose of chemical exposure on a plane was too low to cause physical harm — an argument that was rejected by the judge. Pleus declined to comment.

In perhaps the first decision of its kind, the workers’ compensation judge, Darren Otto, wrote that “it was not necessary to know the exact amount” of inhaled toxic chemicals to establish a “causal relationship” with fume injuries. JetBlue has appealed.

In the hundreds of recent fume events described in the NASA records, pilots and flight attendants frequently report that airlines are pressuring them to fly unsafe planes. The incidents disproportionately affect flight attendants, who lack oxygen masks that can be deployed discreetly behind closed doors. The safety reports cite numerous cases of crew members — particularly flight attendants — being punished for taking sick days after fume events or airlines refusing to count the injuries as work-related.

“We are slowly being poisoned to ill health, or possibly death,” wrote one flight attendant.

Earlier this year, lawsuits were filed against Boeing by three Delta flight attendants and two United flight attendants who allege that fume events left them with lasting health problems. Boeing has denied the claims.

Linda Curry, one of the United flight attendants bringing the suit, said that two years after her January 2018 fume event on a flight from Amsterdam to Newark, she still has memory problems and dizzy spells and can work only part time. “I didn’t know what a fume event was until it happened to me,” said Curry, who lives in Florida. United declined to comment.

In another air contamination lawsuit, five Alaska Airlines flight attendants claimed that fume exposure left them with tremors, memory loss, speech problems and other injuries.

The suit alleged that Boeing had long known of the dangers of air contamination but failed to equip planes with air sensors and filters. Boeing denied the claims.

Dr. Dennis Stumpp, Boeing’s former manager for occupational medicine who has provided expert opinion on behalf of the industry, testified that only one of the 150 or so flight attendants he has examined over the years was legitimately sick from fumes. He diagnosed the rest with problems including hyperventilation and “inadequate coping skills,” according to a transcript of his deposition.

When Stumpp examined one of the Alaska Airlines flight attendants in the case, he concluded that her dizziness and headache on the plane were likely caused by a panic attack, not any toxic chemicals. Stumpp did not respond to a request for comment.

The industry’s experts often diagnose ailments in fume event cases as “somatic,” said Dr. Robert Harrison, a UC San Francisco medical professor who has treated over 100 crew members and was a plaintiffs’ expert in the lawsuit.

“It’s a polite way of saying that the flight attendants are crazy, mostly hysterical women,” Harrison said.

Boeing settled the case in December 2019 for an undisclosed amount.

A pilot's steady decline

Years after fumes engulfed his US Airways flight, Hill was still waging a losing battle with declining health. An Air Force veteran who had dreamed of being a pilot since his youth, Hill slipped into a deep depression after losing his FAA certification, his wife and friends said. Some days he was so confused he would wear his socks into the shower.

Hill couldn’t shake the thought that he had failed to protect his crew and passengers, friends said. At least two passengers had health problems, including a young nurse who said in a deposition that she still suffered memory problems two years after the incident.

Hill and his crew members spent years embroiled in a legal battle for workers’ compensation. To counter their claims, US Airways hired Pleus, the longtime airline industry consultant. Pleus concluded that the chemical exposure levels on Hill’s plane had been too low to cause serious harm.

The judge accepted Pleus’ argument and ruled against Hill.

“He couldn’t believe that the company treated them with such disregard,” Hill’s wife, Penny, remembered.

American Airlines, which merged with US Airways in 2015, did not respond to questions about Hill or other incidents.

“Ensuring the safety of our customers and team members is the top priority for American Airlines,” the company wrote in a statement. “We take cabin odor issues seriously and have devoted extensive efforts ... to address these types of concerns.”

In 2015, Hill traveled to Seattle with his former crew members to tell their story in a union video. His deteriorating health was sadly apparent. Hill wore his old captain’s uniform, but it hung loosely on his frail body.

Afterward, they headed back to the airport. Hill had been there countless times but now seemed confused.

Exchanging worried glances, his old crew members decided they couldn’t leave him alone. They walked Hill to his gate.

Over the next year, Hill’s health continued to decline, friends say. Daily life held more moments of frustration: Forgetting a joke. Losing his balance. Thinking of the career he had lost.

One day in December 2016, at the age of 67, he walked upstairs in his home, grabbed a gun and shot himself in the head.

Hill’s union informed its members about the suicide in an email. The subject line read: “Cabin fumes.”

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Smells on a plane: have you been exposed to toxic chemicals while flying?