On the morning of Sept. 11, 2001, Betty Ong remained calm and professional — an extraordinary feat given that five men had hijacked the American Airlines plane she was working on.Twenty minutes after Flight 11’s takeoff from Boston Logan Airport to Los Angeles, Ong, a flight attendant of 14 years, called the American Airlines reservation desk to report what was happening onboard. “The cockpit is not answering. Somebody’s stabbed in business class and, um, I think there’s Mace, and we can’t breathe,” Ong said. “I don’t know, I think we are getting hijacked.”The plane was the first of four to be overtaken that morning and would eventually crash into the North Tower of the World Trade Center at 8:46 a.m.But Ong’s cool, calm 23-minute phone call from the back of the aircraft on Sept. 11, 2001, provided the very first alert to ground personnel that a hijacking was underway and contributed to the eventual shutdown of U.S. airspace. (Officials credit fellow Flight 11 attendant Madeline “Amy” Sweeney with helping authorities on the ground identify the hijackers by telephoning details about them to her supervisor. Unlike Ong, there’s no public recording of Sweeney’s call.)“No one had trained us for an airplane itself to become the weapon, but they continued doing their jobs until the final moments of their lives,” said Julie Hedrick, the national president of the Association of Professional Flight Attendants (APFA), the union representing 30,000 American Airlines FlightAttendants.San Francisco Chronicle/Hearst Newspapers via Getty ImagesBetty Ong’s cool, calm 23-minute phone call from the back of the aircraft on Sept. 11, 2001, provided the very first alert to ground personnel that a hijacking was underway and contributed to the eventual shutdown of U.S. airspace.Ong, 45 at the time of her death, had requested to work American Airlines Flight 11 that day so she could return to Los Angeles and go on a vacation to Hawaii with her sister. Sweeney, a 35-year-old mom of two young kids, had just returned to work part-time when she received the call to work the Boston-Los Angeles flight to fill in for another flight attendant. In the middle of unimaginable circumstances that morning, both Ong and Sweeney did exactly what flight attendants had been taught to do, Hendrick said: “remain calm, assess the situation, communicate critical information, and care for the people around them. And they did it until the moment of impact.”The terrorist attack on Sept. 11, Hedrick told HuffPost, reminded the world that flight attendants are not simply there for service.“We are safety professionals and aviation’s first responders in the cabin,” Hedrick said. “When something goes wrong at 35,000 feet, there is no fire department around the corner, and no police officer minutes away. The flight attendants on that aircraft are the first line of response.”In 2004, a four-minute tape of Ong’s call was played at the 9/11 Commission, where she was declared a national hero. Her “duty, courage, selflessness and love,” the panel’s chairman said, “may have saved an untold number of lives.”Listening to the call now still rattles Brenda Chabot, a former flight attendant and a member of Silverliners International, a philanthropic and social organization of current and former flight attendants, “All of us in the industry still feel the pain,” she said. “We can understand exactly what the cabin felt like, looked like, how the terrified passengers would be looking to them for some form of reassurance that would be met with a thumbs-up smile regardless of their own feelings.”For those who were flight attendants on Sept. 11, returning to the aircraft afterward was different, according to Hedrick, who has four decades of experience as an American Airlines flight attendant.“The job was different. We looked at the cabin differently. We looked at the cockpit door differently,” she said. “We understood that the assumptions we had relied upon for decades had changed in a matter of hours.”Before that morning, Hedrick said hijacking training reflected everything aviation had experienced up to that point.“We were taught to remain calm, cooperate, avoid escalating the situation, and protect our passengers,” she said. “The expectation was that a hijacked airplane would eventually land somewhere, negotiations would begin, and authorities on the ground would take over.”The aviation industry completely overhauled flight deck security following the Sept. 11 terrorist attacks, which claimed the lives of 2,977 people and injured thousands at the World Trade Center, the Pentagon, and in Somerset County, Pennsylvania.Before Sept. 11, cockpit doors were relatively lightweight, and flight attendants and pilots carried physical keys that could unlock them. To prevent hijackers from forcing their way into the cockpit or stealing keys from crew members, the Federal Aviation Administration mandated major security changes, including hardened cockpit doors designed to resist forcible intrusion.Spencer Platt via Getty ImagesOne of the 9/11 Memorial reflecting pools stands at the 9/11 Memorial Museum as the museum prepares to mark the 25th anniversary of the Sept. 11, 2001, terrorist attacks on Sept. 2, 2026, in New York City.Keeping Ong and Sweeney’s legacy aliveThough both women do not appear to be nearly as well known among the general public as they should be, young flight attendants say their memory is still very much alive. “Betty is someone I think about each time I work the BOS to LAX flight,” said Angela Luna, a Boston-based flight attendant. “She’s well known throughout the aviation community but especially with AA in Boston. We are a small base, and I’ve met some flight attendants who have worked and were even friends with Betty and her crew. Amy, too.”The Flight 11 crew is one of the reasons Luna chose American when deciding which airline she wanted to fly with. Listening to Ong’s call, Lacy-Margaret Hurd, a North Carolina-based flight attendant, said she’s taken aback by her bravery. “Her coworkers were being injured left and right, the pilots were incapacitated, and passengers were probably panicking, but she remained on the line and continued to update those on the ground,” she said. San Francisco Chronicle/Hearst Newspapers via Getty ImagesHarry Ong, brother of Betty Ong, who was a flight attendant on Flight 11 on Sept. 11, 2001, holds a portrait of his sister, Betty Ong, at his home on Tuesday, Sept. 6, 2011, in San Francisco, California.Hurd said the transcript makes her think of all the times her supervisors have told her, “Your training will kick in,” during emergencies.“I think that couldn’t be more true with Betty,” she said. “She’s an incredible example of doing what is necessary, even in the face of what was ultimately the most devastating aviation incident in modern history.”Ong’s siblings, Harry, Cathie and Gloria, have kept her memory alive in their hometown of San Francisco, where a recreation center was renamed in her honor, and Sept. 21 is celebrated as “Betty Ong Day.” In February 2002, the government of Massachusetts established the annual Madeline Amy Sweeney Award for Civilian Bravery to honor her legacy.Harry Ong, Betty’s older brother, told local ABC News affiliate KGO that the anniversary is still painful for the family.“Every year when the anniversary approaches, the tension just builds up and the stress, sometimes debilitating,” he said. “We never forget.”In March 2002, some of Ong’s remains were recovered from ground zero and identified. She was cremated, and her ashes were entombed at Cypress Lawn Memorial Park in Colma, California. Five months later, in August 2002, an initial portion of Sweeney’s identified remains was returned to her family and buried at Mount Hope Cemetery in Acton, Massachusetts.Twenty-five years later, Hedrick said those of us who wear the American Airlines wings “still carry Betty and Madeline with us, along with every crew member who lost their life that day.”