United Airlines Flight 93 was an airline flight that, on September 11, 2001, was hijacked and crashed on purpose. On that day, the flight was to fly from Newark International Airport (later renamed Newark Liberty International Airport), in Newark, New Jersey, USA to San Francisco International Airport.

The aircraft was hijacked by four men as part of the al-Qaeda organized attack on the United States on September 11, 2001. Soon after the flight took off, the hijackers entered the cockpit and overpowered the pilots. They took control of the aircraft and flew it toward Washington, D.C. Several passengers and crew members made telephone calls aboard the flight and learned about the attacks on the World Trade Center and the Pentagon. The passengers then decided to attack the hijackers and retake the aircraft.

The hijackers crashed the plane in a field to prevent the passengers from succeeding in breaching the cockpit door just outside Shanksville, Pennsylvania, about  northwest of Washington, D.C., killing all crew members and passengers. An investigation determined that the actions of the passengers on board had prevented the hijackers from reaching Washington, D.C.

Flight
On September 11, 2001, United Airlines flight 93 was a scheduled morning flight from Newark to San Francisco. The aircraft for the flight was a Boeing 757. The aircraft could carry  182 passengers; but the flight had 37 passengers and 7 crew members, which was low.

Hijackers
The hijackers were led by Ziad Jarrah, a member of al-Qaeda. Jarrah was born in Lebanon. He moved to Germany in 1996, enrolling at the University of Greifswald to study German. A year later, he moved to Hamburg, Germany and began studying aeronautical engineering at Hamburg University of Applied Sciences. While living in Hamburg, Jarrah associated with a radical Hamburg cell of terrorists.

In November 1999, Jarrah left for Afghanistan, where he spent three months. In Afghanistan in January 2000, he met with al-Qaeda leader Osama bin Laden. Jarrah returned to Germany at the end of January and obtained a new passport with no Afghan passport stamps in February by falsely reporting his passport as stolen.

In June 2000, Jarrah arrived in Florida in June 2000. He began taking flying lessons as well as training in hand-to-hand combat.

Four other hijackers were trained to physically fight with the crew. Three of them accompanied Jarrah on Flight 93. They were Ahmed al-Nami, Hamza al-Ghamdi and Mohand al-Shehri].

On August 3, 2001, the intended fifth hijacker, Mohammed al-Qahtani, flew to Orlando, Florida, USA from Dubai. He was questioned by officials, who did not believe that he could support himself with only $2,800 cash, and suspicious that he intended to become an illegal immigrant because he was using a one-way ticket. He was sent back to Dubai, and later  returned to Saudi Arabia.

At 5:01 a.m. on the morning of September 11, Jarrah placed a cell phone call from Newark to Marwan al-Shehhi, the hijacker pilot of United Airlines Flight 175, in Boston. This call was apparently to confirm that the attacks were ready to begin.

Haznawi and Ghamdi boarded the aircraft at 07:39 and sat in first class seats 6B and 3D respectively. Nami boarded one minute later and sat in first class seat 3C. Before boarding the plane, Jarrah made five telephone calls to Lebanon, one to France, and one to his girlfriend, Aysel Sengün, in Germany, to whom he'd sent a farewell letter the day before. He said "I love you" three times, then hung up when she asked what was up.

With the attacks unfolding, air traffic officials began issuing warnings through the Aircraft Communication Addressing and Reporting System (ACARS). Ed Ballinger, the United flight dispatcher, began sending text cockpit warnings to United Airlines flights at 09:19, 17 minutes after he became aware of Flight 175's impact. Ballinger was responsible for multiple flights, and he sent the message to Flight93 at 09:23. Ballinger received a routine ACARS message from Flight93 at 09:21: "Good morning...Nice clb (climb) outta EWR [Newark Airport]." The message commented about the sights from the cockpit and the weather, and was signed off with the initial, "J.", indicating it came from Jason Dahl, who knew Ballinger. At 09:22, after learning of the events at the World Trade Center, LeRoy Homer's wife, Melody Homer, had an ACARS message sent to her husband in the cockpit asking if he was all right. At 09:24, Flight93 received Ballinger's ACARS warning, "Beware any cockpit intrusiontwo a/c [aircraft] hit World Trade Center". At 09:26, after the pilots twice checked in with a routine altitude and weather report to an air traffic controller at the FAA's Cleveland Center, Dahl wrote a hasty, misspelled ACARS reply: "Ed cofirm latest mssg plz-Jason". At 09:27:25, as the aircraft was crossing into eastern Ohio airspace, the flight crew responded to a routine radio call from a Cleveland air traffic controller, who told them to watch for another plane twelve miles away and two thousand feet above them. They said contact was negative and they were looking. This was the last communication made by the flight crew before the hijacking.

The hijacking began at 09:28. By this time, Flights 11 and 175 had already crashed into the World Trade Center and Flight77 was within nine minutes of striking the Pentagon. The hijackers on those flights had waited no more than thirty minutes to commandeer the aircraft, most likely striking after the seat belt sign had been turned off and cabin service had begun. It is unknown why the hijackers on Flight93 waited 46 minutes to begin their assault. According to reports from passengers and crew, the hijackers tied red bandanas around their heads and sprang from their seats. At 9:28:05, as the flight cruised at 35,000 feet over eastern Ohio, the plane abruptly dropped 685 feet. At 09:28:17, eleven seconds into the descent, Cleveland heard a man scream into the cockpit radio: "Mayday! Mayday! Mayday!" A second raspy shout went, "Hey! Get out of here!"  Cleveland Air Traffic Controller John Werth didn't know the source of the call he heard, and could only make out what he heard as "just some gruttural, gruttural sounds." He responded, "Somebody call Cleveland?", before he noticed Flight 93's rapid descent and heard at 09:28:50 another transmission from the cockpit, screams alongside an even more desperate and garbled refrain: "Hey! Get out of here! Get out of here!" The commission made no conclusion as to whether it was Dahl or co-pilot LeRoy Homer giving the distress call, but when Melody Homer and Sandy Dahl, Jason Dahl's wife, together listened to the tape, Melody Homer claimed to have recognised her husband’s voice as the man who was shouting. The flight dropped  in half a minute before the hijackers stabilized the aircraft at 34,315 feet, and soon began climbing southeast. Of the four hijacked aircraft on 9/11, Flight93 was the only aircraft that broadcast a distress call. It is likely that because the pilots had been warned of the World Trade Center attacks and to beware of cockpit intrusion, when the hijackers attacked them, they purposely pressed on the talk button of the radio microphone, so sounds of the struggle in the cockpit will be heard by FAA ground controllers and by pilots of planes on the same radio frequency. Werth believed it was not just a call for help, but a warning as well. During the next two minutes, Werth made seven attempts to contact Flight 93, with no reply, while other controllers moved nearby flights out of the way.

The cockpit voice recorder began recording the final thirty minutes of Flight93 at 09:31:57. At this moment, it recorded a hijacker’s voice, thought to be Jarrah, speaking with a halting command of accented English and breathing and panting heavily, apparently from exertion, perhaps from a struggle, "Ladies and gentlemen: here the captain. Please sit down, keep remaining seating. We have a bomb on board. So sit." The commission believed Jarrah tried to make an announcement to the passengers, but keyed the wrong switch, sending the message to Cleveland controllers; Mohamed Atta had made the same error on Flight 11. Werth understood the transmission, and tried to keep the hijacker pilot talking, responding, "Calling Cleveland center, you're unreadable. Say again, slowly." He sent a new text warning message to Flight 93: “High Security Alert. Secure Cockpit.” Werth asked other pilots in his sector to tail Flight 93, to keep eyes on the hijacked plane.

The flight recordings indicate that a wounded man, believed to be Dahl, was moaning in the cockpit. The man pleaded, "No more," or "No," repeatedly, as the hijackers shouted for him to sit down and to stop touching something. Sandy believes that Dahl took actions to interfere with the hijackers, including possibly disengaging the autopilot, and rerouting the plane's radio frequency so that Jarrah's attempts to communicate with the passengers were instead transmitted to air traffic controllers.

Tom Burnett made several phone calls to his wife beginning at 09:30:32 from rows 24 and 25, though he was assigned a seat in row 4. Burnett explained that the plane had been hijacked by men claiming to have a bomb. He also said a passenger had been stabbed with a knife and that he believed the bomb threat was a ruse to control the passengers. He told her to call the authorities, then hung up. During his second call to her, Burnett said the stabbed passenger was dead; he checked for a pulse but found none. It is believed that passenger Mark Rothenberg was the victim. Rothenberg was the only first class passenger who didn't make a phone call after the hijacking. Rothenberg was seated in 5B, and Haznawi sat directly behind him in 6B. On Flight 11, Satam al-Suqami in seat 10B attacked passenger Daniel Lewin, who was seated directly in front of him in 9B. One assumption is that Haznawi attacked Rothenberg, unprovoked, to frighten other passengers and crew into compliance. Alternatively, Rothenberg may have attempted to stop the hijacking and confront the hijackers. Burnett's wife informed him of the attacks on the World Trade Center and he replied that the hijackers were "talking about crashing this plane.... Oh my God. It's a suicide mission." He began asking her for information about the attacks, interrupting her from time to time to tell the others nearby what she was saying. Then he hung up. In his next call, Burnett, who had been informed of the attack on the Pentagon, said he was putting together a plan and that "a group" were helping him. He ended his last call by saying, "Don't worry, we're going to do something."

In the cockpit, the wounded man continued to moan and seemingly repeat disengaging the autopilot, as at 09:40, there were horn sounds that indicating the hijackers were repeatedly having trouble with the autopilot and were fiddling with a green knob. "This green knob?" one of the hijackers asks the other in Arabic. Another hijacker responded, "Yes, that's the one."  At 09:41:56, the wounded man, in a moaning tone, said, "Oh, man!".

References

Other websites 
 United Airlines Flight 93  Brief summary, as well as complete victim list

September 11 attacks
2001 aviation disasters