Cleveland flight controller Stacey Taylor has been warned to watch transcontinental flights heading west for anything suspicious. She later recalls, “I hear one of the controllers behind me go, ‘Oh, my God, oh my God,’ and he starts yelling for the supervisor. He goes, ‘What is this plane doing? What is this plane doing?’ I wasn’t that busy at the time, and I pulled it up on my screen and he was climbing and descending and climbing and descending, but very gradually. He’d go up 300 feet, he’d go down 300 feet. And it turned out to be United 93.” (Note the time of this incident is not specified, but presumably it is prior to when Cleveland controllers note Flight 93 descends 700 feet at 9:29 a.m. [MSNBC, 9/11/2002]
9:35 a.m. September 11, 2001: Silent Flight 93 Climbs and Drops; NORAD Still Not Notified
When Flight 93 is over Youngstown, Ohio, Stacey Taylor and other Cleveland flight controllers see it rapidly climb 6,000 feet above its assigned altitude of 35,000 feet and then rapidly descend. The plane drops so quickly toward Cleveland that the flight controllers worry they might be the target. Other accounts say the climb occurs around 9:35 a.m. Controllers continue to try to contact the plane but still get no response. [Guardian, 10/17/2001; USA Today, 8/12/2002; 9/11 Commission, 6/17/2004 
]
10:02 a.m. September 11, 2001: Flight 93’s Transponder Briefly Comes Back On
Flight 93’s transponder, which was switched off after Flight 93 was hijacked, is turned back on just before the plane crashes, thereby revealing the plane’s altitude to air traffic controllers at the FAA’s Cleveland Center. [Federal Bureau of Investigation, 9/11/2001; MSNBC, 9/11/2002] A transponder is a device that sends a plane’s identifying information, speed, and altitude to controllers’ radar screens. [Washington Post, 9/16/2001] Flight 93’s transponder was switched off at around 9:40 a.m. (see (9:40 a.m.) September 11, 2001), although Cleveland Center controllers have still been able to follow Flight 93 on “primary radar,” which shows less information about a flight (see (9:41 a.m.-10:06 a.m.) September 11, 2001). [Federal Bureau of Investigation, 1/8/2002; 9/11 Commission, 7/24/2004, pp. 29; Cleveland Plain Dealer, 7/3/2011]
Plane Shown to Be Flying at 8,200 Feet – Flight 93’s transponder is reactivated at 10:02 a.m. and 50 seconds, and then stays on for “approximately 20 seconds,” according to “information from the flight data” provided to the FBI later today by Rick Kettell, the manager of the Cleveland Center. After the transponder is turned back on, Flight 93’s radar track is observed by Cleveland Center controllers Linda Justice and Stacey Taylor. The information from the transponder shows them that Flight 93 is at an altitude of 8,200 feet. [Federal Bureau of Investigation, 9/11/2001; Federal Aviation Administration, 9/16/2001 ; 9/11 Commission, 10/2/2003 ]
Plane Soon Disappears from Radar Screens – Flight 93 will crash into the ground at 10:03 a.m. and 11 seconds, according to the 9/11 Commission Report, less than 30 seconds after the transponder is reactivated (see (10:03 a.m.-10:10 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 30] Cleveland Center controllers will see the plane completely disappear from their radar screens around that time. [MSNBC, 9/11/2002] A Cleveland Center controller will then report, apparently over an FAA teleconference, that Flight 93’s transponder “came on briefly and then it went back off with the primary, and now we’ve lost him completely.” [Federal Aviation Administration, 9/11/2001] “I had two radar hits on [Flight 93],” Taylor will recall, adding that she then “lost the primary target on [Flight 93] and we suspected it had gone down.” [Federal Aviation Administration, 9/16/2001 ] The reason Flight 93’s transponder is switched back on just before the plane crashes is unclear. Taylor will comment, a year after 9/11: “That’s something we’ve always wanted to know. Why did the transponder come back on?” She will say Cleveland Center controllers wondered this because they believed that “the hijackers had shut it off so that they couldn’t be tracked.” [MSNBC, 9/11/2002]
Before 10:06 a.m. September 11, 2001: Fighters Trailing Flight 93 When It Crashes, According to Some Accounts; Other Accounts Contradict This
Shortly after 9/11, the North American Aerospace Defense Command (NORAD) will say the nearest fighter jets to Flight 93 at the time it crashes are the F-16s from Langley Air Force Base that are flying a combat air patrol over Washington, DC (see (Between 9:49 a.m. and 11:00 a.m.) September 11, 2001). [North American Aerospace Defense Command, 9/18/2001; 9/11 Commission, 8/26/2004, pp. 34] Other accounts will conflict over whether or not there are any fighter jets near Flight 93 when it goes down: 
Two days after the attacks, it will be reported that an unnamed New England air traffic controller has ignored a ban on controllers speaking to the media, and this controller claims “that an F-16 fighter closely pursued Flight 93.… [T]he F-16 made 360-degree turns to remain close to the commercial jet.” The controller adds that the fighter pilot “must’ve seen the whole thing.” He reportedly learned this from speaking to controllers who were closer to the crash. [Telegraph (Nashua), 9/12/2001; Associated Press, 9/13/2001] Five days after the attacks, on September 16, CBS News will report that two F-16s are tailing Flight 93 and are within 60 miles of it when it goes down. [CBS News, 9/16/2001; Independent, 8/13/2002] But, also on September 16, Major General Paul Weaver, the director of the Air National Guard, will say that no military planes were sent after Flight 93. [Seattle Times, 9/16/2001] In April 2002, Anthony Kuczynski will tell the University of St. Thomas’s weekly newspaper that he had flown toward Pittsburgh alongside two F-16s on 9/11. He says he was piloting an E-3 Sentry AWACS plane, which has advanced radar and surveillance equipment that can be used to direct fighter jets to their targets. He was just about to intercept Flight 93 when it crashed. He says, “I was given direct orders to shoot down an airliner.” (E-3s are unarmed, so, if this account is accurate, the order presumably applied to the fighters Kuczynski was accompanying.) [St. Thomas Aquin, 4/12/2002; US Air Force, 9/22/2015] A year after the attacks, ABC News will report that the “closest fighters” to Flight 93 when it crashes “are two F-16 pilots on a training mission from Selfridge Air National Guard Base” near Detroit, Michigan. These are ordered after Flight 93, according to some accounts, even though they are unarmed. [ABC News, 8/30/2002; ABC News, 9/11/2002] However, other accounts will state that these jets are in fact ordered to intercept another aircraft, Delta 1989, or are simply told to return to their base (see (9:55 a.m.) September 11, 2001 and (9:56 a.m.-10:29 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 28; Mount Clemens-Clinton-Harrison Journal, 9/6/2006; Spencer, 2008, pp. 178] Stacey Taylor, an air traffic controller at the FAA’s Cleveland Center, will claim not to have seen any fighter jets on radar around the area of the crash. [MSNBC, 9/11/2002] Five years after 9/11, Bill Keaton, a Cleveland Center controller who tracked Flight 93 as it flew eastward (see (9:41 a.m.-10:06 a.m.) September 11, 2001), will be asked whether there were fighter jets in the vicinity of the plane when it crashed. He will reply, “[T]hat goes beyond the scope of what I can comment on.” (Air traffic controllers reportedly can lose their security clearances if they discuss the movements of military aircraft.) [Cleveland Free Times, 9/6/2006]
10:07 a.m. September 11, 2001: Business Jet Asked to Help Locate Flight 93 Crash Site
According to some accounts, following a request from the FAA’s Cleveland Center, a Fairchild Falcon 20 business jet reports seeing puffs of smoke in the area of Flight 93’s last known position. [Pittsburgh Post-Gazette, 9/16/2001; Federal Aviation Administration, 9/17/2001 ] The FBI later says the business jet was within 20 miles of Flight 93 when it crashed, at an altitude of 37,000 feet, and on its way to Johnstown. It was asked to descend to 5,000 feet to help locate the crash site for the benefit of the responding emergency crews. [Pittsburgh Channel, 9/15/2001] Stacey Taylor appears to be the Cleveland Center controller who made the request. She later recalls: “I had another airplane [other than Flight 93] that I was working. And I told him, I said, ‘Sir,’ I said, ‘I think we have an aircraft down.’ I said, ‘This is entirely up to you, but if you’d be willing to fly over the last place that we spotted this airplane—and see if you can see anything.‘… So he flew over and at first he didn’t see anything and then he said, ‘We see a great big plume or a cloud of smoke.’” [MSNBC, 9/9/2006] The business jet belongs to VF Corp, a Greensboro, North Carolina clothing firm. [Pittsburgh Post-Gazette, 9/16/2001] According to David Newell, VF Corp’s director of aviation and travel, Cleveland Center contacted the plane’s copilot Yates Gladwell when it was at an altitude “in the neighborhood of 3,000 to 4,000 ft,” rather than 37,000 feet, as claimed by the FBI. He will add: “They got down within 1,500 ft. of the ground when they circled. They saw a hole in the ground with smoke coming out of it. They pinpointed the location and then continued on.” [Popular Mechanics, 3/2005] This incident occurs around 40 minutes after the FAA initiated a nationwide ground stop, which required planes in the air to land as soon as reasonable (see (9:26 a.m.) September 11, 2001). [Time, 9/14/2001; 9/11 Commission, 7/24/2004, pp. 25] The FBI will claim the VF Corp business jet is probably the plane some witnesses on the ground see up above, shortly after the crash of Flight 93 (see (Before and After 10:06 a.m.) September 11, 2001). [Pittsburgh Channel, 9/15/2001] However, at least two witnesses say they saw a plane overhead even before the time of the Flight 93 crash, and one of them describes it as “definitely military,” rather than a business jet. Also, some will describe it as flying much lower than the Falcon 20 was—just “40 feet above my head,” according to one witness. [Bergen Record, 9/14/2001; Mirror, 9/12/2002]
10:08 a.m. September 11, 2001: Military Cargo Plane Pilot Asked to Verify Flight 93 Crash
Cleveland Center air traffic controller Stacey Taylor has asked a nearby C-130 pilot to look at Flight 93’s last position and see if he can find anything. Remarkably, this C-130 pilot, Lt. Col. Steve O’Brien, is the same pilot who was asked by air traffic control to observe Flight 77 as it crashed into the Pentagon earlier on (see 9.36 a.m. September 11, 2001). O’Brien tells Taylor that he saw smoke from the crash shortly after the hijacked plane went down. [Guardian, 10/17/2001; MSNBC, 9/11/2002; 9/11 Commission, 6/17/2004] An article in the London Independent will later suggest that Flight 93 might have been brought down by the US military using “electronic warfare applications” that can disrupt the mechanisms of an airplane (See August 13, 2002); it will refer to this C-130, since “in 1995 the Air Force installed ‘electronic suites’ in at least 28 of its C-130s—capable, among other things, of emitting lethal jamming signals.” [Independent, 8/13/2002]
