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Operation Pearl
by Professor A. K. Dewdney
August 2003

Editor's note:  Some people have said that this account of the events of September 11th 2001 (a detailed extension of the Valentine-Plissken Hypothesis) is "too convoluted to understand".  Actually it's quite simple.  Here's a synopsis for those who have a slight comprehension problem or don't have time to read it all:

  1. Four commercial passenger jets (American Airlines Flights 11 and 77 and United Airlines Flights 93 and 175) take off and shortly after the pilots are ordered to land at a designated airport with a military presence.
  2. Two previously-prepared planes (one a Boeing 767, painted up to look like a United Airlines jet and loaded with extra jet fuel) take off and are flown by remote control to intercept the flight paths of AA 11 and UA 175 so as to deceive the air traffic controllers.
  3. These (substituted) jets then fly toward Manhattan; the first crashes into the North Tower and (eighteen minutes later) the second crashes into the South Tower.
  4. A fighter jet (under remote control), or a cruise missile, crashes into the Pentagon.
  5. Back at the airport the (innocent) passengers from three of the Boeings are transferred to the fourth (UA 93).
  6. This plane takes off, flies toward Washington, and is shot down by a U.S. Air Force jet over Pennsylvania, eliminating the innocent witnesses to the diversion of the passenger planes.
  7. Under cover of darkness later that evening the other three Boeings are flown by remote control out over the Atlantic, are scuttled and end up in pieces at the bottom of the ocean.

1 Summary

It is possible to produce the appearance of a terrorist attack on the United States by means that do not employ terrorists, as such, but by the simple substitution of one aircraft for another, particularly when the transponders of the aircraft involved are turned off. The only people who need to be deceived by such an operation are the radar operators at air traffic control (ATC) centers.

The scenario explored here, called Operation Pearl (after Pearl Harbor), has been described in sufficient operational detail that sound judgments can be made about a) feasibility and b) consistency with evidence on the ground. At the time of this writing it is probably the best available description of what probably took place on September 11, 2001.

Under the Operation Pearl scenario, the passengers of all four flights died in an aerial explosion over Shanksville, PA and the remaining three airliners are at the bottom of the Atlantic Ocean.

2 Introduction

Since March of 2002, persons probing the web for further information about the 9/11 attacks could not fail to encounter, sooner or later, a scenario advanced by Carol Valentine. Called the "Flight of the Bumble Planes" (Valentine 2002), it allegedly came from an informant who would only identify himself as "Snake Plissken," the name of the hero of the movie, Escape from New York (footnote 1).

The informant outlined the basic hijacking method in an email message to Carol Valentine, comparing it to a flight of bumble bees. Watching bees as they buzz around among flowers, it is very difficult to follow individual bees, since they are always passing close to one another.

This metaphor translates into the flight of two aircraft in a confined locale of airspace. If the separation between them is small enough, radar operators will see not two aircraft, but one. On the morning of September 11, 2001, according to this scenario, all four "hijacked" aircraft landed at a single airport or air base, transferring their passengers to a single aircraft, the one that crashed in Pennsylvania. Meanwhile, remotely controlled aircraft of various types carried out the actual attacks. The scenario, as presented by Valentine, consists of little more than I have presented here.

Of course, there is a vast difference between an outline and a detailed operational plan. It may turn out, for example, that any attempt to imagine how a specific scheme is implemented runs into snags, as in the attempt by Spencer (2003) to get all four aircraft to one air base long enough for the combined list of over 200 passengers to board a single aircraft, take off and crash near Shanksville, Pennsylvania. Spencer, however, assumed that the takedown of aircraft coincided with the turning off of transponders. In the present paper the scenario is modified to allow takedown prior to the turning off of transponders, assuming that takedown occurred at the first deviation of each aircraft from its flight plan. The refurbished scenario has now been completed to a level of detail that makes it possible to evaluate its feasibility, as well as its consistency with the evidence, as presently acquired and developed.

A scenario named Ghost Riders in the Sky was previously constructed by the author (Dewdney 2002). The purpose of that scenario was simply to demonstrate that alternate scenarios that fitted all the facts (as then understood by the author) could be constructed. The scenario involved killing all the passengers and flight crew with a fast-acting nerve agent, then triggering a software patch in the aircraft flight control systems to direct the aircraft to their various destinations. However, when it became evident that no Boeing 757 had actually struck the Pentagon (see The Pentagon Evidence, also on this website), the scenario was rendered invalid. The Ghost Riders scenario, like the Bush-Cheney scenario, required that the aircraft that struck their respective targets were as advertised, two 767s and two 757s.

The fact that the Ghost Riders scenario must now be rejected illustrates the nature of this inquiry. As in science, hypotheses must be formulated, then tested against the available evidence. If found wanting in the light of that evidence, they must be rejected. It is normal in any scientific inquiry to formulate and analyze more than one hypothesis before one is found that actually works. The same remark also applies to criminal investigations.

3 The Evidence Filter

Any scenario constructed to account for the events of September 11 2001 must pass a graduated test, as embodied in the following items. These fall into three classes:

Suspicious circumstances

  1. Four of the named hijackers were not in the United States.
  2. The WTC towers collapsed without adequate heat stress.
  3. Smaller aircraft accompanied Flights 77 and 93.
  4. Most of the alleged hijackers were rather poor pilots.
  5. Evidence of the alleged hijackers developed too quickly.
  6. Westward excursion of Flights UA93 and AA77 are inexplicable as terrorists hurrying to targets."


  1. The US Air Force failed to intercept any of the flights.
  2. The hijackers' names did not show up on passenger lists.
  3. The hijackers' faces did not appear on boarding gate videos.
  4. Black boxes were missing from all but one flight.


  1. The Pentagon was not struck by a large passenger aircraft.
  2. Cellphone calls alleged to have been made by passengers were essentially impossible.

A successful scenario must at least explain the contradictions and account for a majority of the anomalies. It is of course desirable that it also account for the suspicious circumstances, but no scenario need stand or fall in this regard.

It must be remarked that the only scenario ever supplied to the public via the official media was the Bush-Cheney scenario, that Arab hijackers seized control of the four aircraft and proceeded to pilot them into national landmarks, killing both themselves and their passengers. Clearly, the Bush-Cheney scenario, considered in detail, explains none of the suspicious circumstances, none of the anomalies and is directly contradicted by the facts adduced in the third category. As scenarios go, it is a distinct failure.

4 Technical Elements

The two major technical aspects of the Operation Pearl scenario involve radar and remote control. Radar technology has been with us since World War Two, some 60 years ago. Remote control technology has been around in various forms for at least twenty years. With a basic understanding of both radar and remote control in relation to 9/11, it becomes possible for the average citizen to think for himself or herself.

4.1 Radar Substitution

A radar screen is essentially a circular CRT (cathode ray tube — like a television screen) that displays aircraft within the circular airspace represented on the screen. Radar operators are the only people who can be aware of what planes are in the sky and where they are going. The vast majority of people are completely unaware of what is going on in any large volume of airspace and, when an aircraft passes overhead, can usually not tell one type from another, let alone what airline or aviation company may own it. This observation, while something of a commonplace, has important implications. If an organization wishes to substitute one aircraft for another without anyone knowing it, the only people it has to deceive are the radar operators.

The resolution of a radar screen is the size of the smallest point that can appear there, approximately two millimeters in diameter — a "blip." A typical radar screen, less than a meter in diameter, could therefore be described as less than 500 "blips" wide. If the airspace represented on the screen were 500 kilometers in diameter (approximately 300 miles, a not atypical size), each blip would represent a piece of airspace that is more than 500/500 = 1 kilometer wide.

In other words, as soon as two aircraft get within a kilometer of one another, there would be a tendency for their respective blips to merge. With half a kilometer separation or less, the two aircraft could easily appear as one.

Of course, two aircraft that are that close together run a distinct risk of collision — unless they are at different altitudes. Radar screens are two-dimensional in that they represent airspace in the same way as a map, with the vertical dimension of altitude suppressed. Thus, without additional information in the form of a displayed altitude number, it is impossible for a radar operator to tell whether two merged blips represent a potential collision or not. Altitude information is displayed if an aircraft's transponder is turned on, otherwise, the radar operator has no idea of the altitude at which an aircraft happens to be flying.

If one aircraft happens to be within a half kilometer of another, whether above that aircraft or below it, the radar operator will see only one aircraft, as long as the two maintain a horizontal separation that is no greater than half a kilometer (about 500 yards).

Imagine now two aircraft, both headed for the same approximate point on the radar screen, both with their transponders turned off. One is well above the other but, as the blips merge, both planes swerve, each taking the other's former direction. The operator would simply see the aircraft cross and would have no way to realize that a swap had taken place.

There are many other swapping patterns available. For example, one plane could apparently catch up and "pass" another when, in fact, it slowed after the blips merged, even as the other speeded up.

Another method involves the replacement aircraft climbing out of a valley where it would be invisible to distant radars, even as the other aircraft descended into the valley. Again, a radar operator would see a more or less seamless flight without realizing that he or she had been momentarily seeing not one, but two aircraft on the radar screen.

Of course, if the transponders are turned on, as explained in the next section, such confusion is less likely to occur. Even in this case, however, the deception can be complete if the aircraft switch transponder codes.

4.2 Aircraft transponders

Every commercial passenger jet carries a transponder, a device that emits a special radio message whenever it senses an incoming radar wave. The signal carries the transponder code, a multi-digit number that serves to identify the particular aircraft to radar operators at air traffic control centers. The purpose of the code is to make it clear to ATC operators which plane is which. Other information sent by the transponder includes the altitude at which the aircraft is flying. Transponders were implemented many years ago precisely for the reason that radar blips are otherwise easily confused. Transponders make the radar operator's job much easier.

The pilot of an airliner can turn the transponder on or off in the cockpit. He or she can also change the code by keying in a new number.

Transponder codes for all aircraft departing from a given air traffic control region are assigned by the ATC authority more or less arbitrarily. The only important criterion for the numbers so assigned is that they all be different. It sometimes happens that an aircraft entering the control area carries the same transponder code as another aircraft that is already in the area. In such a case, one of the pilots is requested to change his or her code to avoid confusion.

4.3 Remote Control

A remote control system of the type used in this scenario uses a signal interface that does two things: It reads signals from a ground station and sends signals back to it. Both sets of signals must pass through the aircraft's antenna system. In the Boeing 757 and 767 the antenna system is located in the forward belly of the aircraft.

The outgoing signal from the aircraft would include a video signal from a camera located in the nose or other forward portion of the aircraft. Flight data such as control positions, airspeed and other instrument readings are also included in the outgoing signal. The incoming signal from the ground station would include the position of a virtual control yoke (governing direction of aircraft), thrust, trim, and other essential flight parameters.

The virtual pilot would sit in front of a reduced instrument panel and a video monitor. A simplified control yoke or "joystick" control would also be part of the operator's equipment. The remote pilot would watch the instruments, as well as the video image, making continuing adjustments in the aircraft's flight path, just as if he or she sat in the cockpit of the actual aircraft.

Many claims of the attacking aircraft being under "remote control" have appeared on the web since 9/11, but typically with little or no supporting documentation. The claim of a pre-installed anti-hijacking system (Vialls 2001) has proved impossible to verify. Similarly, claims that Global Hawk technology (USAF 98) was used are rampant, but do not quite fit the specific version of Operation Pearl presented here. For one thing, the Global Hawk system does not use remote visual guidance, but onboard navigation electronics that bypass the need for direct, minute-by-minute human control.

The system invoked for the attacks in Operation Pearl is based on the Predator unmanned surveillance vehicle (USAF undated), a modularized aircraft that can be broken into components for ease of shipping and rapid deployment. One of the components includes a remote guidance module which could be refitted to another aircraft (with appropriate modifications) without the need to strip a predator vehicle. The predator operates under remote human guidance from a ground station that, once deployed, would require as few as two human operators during a "secure" operation.

A second possibility involves a system known as a "flight termination system," manufactured by the System Planning Corporation. (SPC 2000) This system permits hands-on control of a nearly endless variety of aircraft, the control interface being to a large degree customizable. For the purposes of the Operation Pearl scenario, either of these systems might well be adaptable to the remote operations of nonmilitary jet aircraft.

Without question, however, the basic technology for the remote guidance of aircraft has been on hand for many years. For a large intelligence organization it would be a straightforward technical operation to install a remote control system in virtually any type of aircraft, whether a large commercial airliner or anything smaller. The aircraft carrying the installation would be available and prepared in advance, then substituted for the passenger aircraft it was meant to replace.

4.4 Electronic towing

An interesting but different form of remote control is invoked by the Operation Pearl scenario in the "cleanup" phase, namely the disposal of the three aircraft that did not crash in Pennsylvania or anywhere else. I call this facility "electronic towing," It consists of two "black boxes" that pick up signals from an aircraft's data bus, a shared electronic pathway travelled by all electronic signals that control the aircraft. (Spitzer 2000) Each black box can read the bus through the data bus monitor, as well as insert information into the bus. Because the connections are already available, installation of the boxes could be completed in a matter of hours on any aircraft. In this relatively simple form of remote control, one aircraft would be called the "slave," the other the "master." In addition, two 2-way radios allow the black boxes to communicate, specifically for the master box to send its signals to the slave box. Under identical conditions, the slave aircraft will do precisely what the master aircraft does. Such control signals could also be taped and replayed later to invoke in the slave aircraft exactly the same behavior as the master.

To initiate towing, the master aircraft takes off first, while the slave aircraft remains on the runway, completely unoccupied. As soon (or as late) as the pilot of the master aircraft wishes to, a recording of the master signals is played over the radio to the slave aircraft, which then takes off precisely as the master aircraft did. The slave will then follow the master wherever the pilot of the master wishes to go. With a short time delay in the control loop, the slave aircraft would appear literally to be towed by the master, always maintaining the same distance and position behind it. If the pilot of the master aircraft wished to "unhitch" the slave, he could simply cut the control signal. Over the ocean, the unhitched aircraft might fly until it runs out of fuel or it might be blown up by implanted explosives.

5 Operation Pearl

In the detailed scenario to follow, Harrisburg International Airport was selected as the base of operations. However, any airport, airbase or landing strip of suitable length within, say, 50 km of Harrisburg might work just as well. The following table displays the takeoff times of the respective aircraft from Boston's logan Airport, Newark International, and Washington's Dulles Airport on the morning of September 11, 2001. Assuming a takedown at the first deviation, the flying times to Harrisburg International Airport are calculated and the arrival times of the respective aircraft at Harrisburg are displayed. All flying times are based on the assumption of an average airspeed of 805 km/h (500 mph). In each case, 5 minutes is added at either end of the flight to allow for takeoffs and landings.

Flight Take-down Distance to Harrisburg Flying Time Arrival
AA11 8:16 am 420 km 32 + 5 min. 8:53 am
UA175 8:42 am 200 km 15 + 5 min. 9:02 am
UA93 8:42 am 260 km 20 + 5 min. 9:07 am
AA77 8:46 am 240 km 18 + 5 min. 9:09 am

As a convenience, the takedown of Flight UA93 has been made simultaneous with the aircraft's takeoff. Since the flight path was directed toward Harrisburg, the takedown time is not relevant to the calculation as it could have taken place anywhere along the route, yielding the same result for arrival in Harrisburg.

As a feasibility check, we may now calculate whether there was adequate time on the ground in Harrisburg to deplane three of the aircraft, loading their passengers onto Flight UA93. Working backwards, the flight of UA93 from Harrisburg to Shanksville involved a distance of 144 km for a flight time of 18 minutes. Thus, to "crash" at 10:06 am, it had to leave Harrisburg no later than 9:45 am. This would give the agents of Operation Pearl (see Appendix C) some 36 minutes to board the passengers from the other flights onto Flight UA93.

A master timetable for the entire operation has been provided at the end of this article. Readers may wish to consult this table, along with the accompanying map, in order to obtain a birdseye view of all four flights.

We will now examine key elements of the scenario in the form of mini-dramatizations that place the reader in the scene, as it were. The following sketches supply enough detail to provide a secondary check on feasibility. I have used a compact notation to refer to the four replacement flights, simply appending an "X" to the flight number. Thus "UA175X" refers to the replacement aircraft for flight UA175.

5.1 The takedown

The morning of September 11 dawned bright and clear over Boston's Logan Airport as crews arrived for the first flights of the day. The departure lounge for American Airlines Flight 11 was already filling with passengers when John Ogonowski, the pilot, and Thomas McGuinness, the second officer, arrived to board their Boeing 767 and begin the preflight check.

As passengers slowly filed past the check-in counter and onto the boarding ramp, the flight officers proceeded through the cockpit checklist. The weather would be perfect for flying. Only one little detail soured Ogonowski's day. He had been informed that an FBI antiterrorism agent would be aboard the aircraft. Among the incoming passengers, a nondescript gentleman in a business suit settled into a seat in first class. Just as the giant turbofan engines began their warmup, a stewardess reminded the gentleman, now scribbling on a piece of paper, to fasten his lap belt.

"Certainly. Er, would you mind giving this note to the captain?"

She took the note forward, handing it to Ogonowski, who read it with more than passing interest.

"Hmmm. I guess it's real. Take a look at this, Tom."

McGuinness read the note.

My name is Bill Proctor, FBI anti-hijacking team. We have information that hijackers may be aboard the aircraft today. I repeat, may. My partner and I are on this flight to prevent such a happening. We wish our presence on board to be kept confidential. I am in seat 7A. Thank you for your cooperation.

"I'd better take a look at this guy," said Ogonowski. Take her out while I go back for some coffee."

The engines roared to life and the aircraft began to taxi out to the runway. Ogonowski spotted the gentleman and pulled the note from his breast pocket. The gentleman nodded and smiled back.

"I'm sorry. I still have to ask to see your ID."

"Certainly." The man handed Ogonowski a small wallet, flipped open to reveal the famous logo.

On his way to the galley, Ogonowski scrutinized the passengers from the corner of his eyes. Instinctively, he looked for swarthy, middle eastern types, somewhat reassured to see none.

The takeoff was smooth and the 767 climbed into clear blue skies, with several wisps of cirrus off to the west. About 15 minutes into the flight, just as the flight officers were relaxing and thinking a hijacking rather unlikely, another note arrived via the stewardess.

We have spotted two terrorists on board. I must come forward to discuss the situation with you. Bill

"What the hell! Is this guy serious?"

"Jeez. I guess so."

Inside the cockpit, the gentleman wore a serious frown.

"We'll have to land at Harrisburg, where we have facilities to deal with this problem. Use the 80.7 kHz frequency and do not engage in any other radio activity at this time, please. Identify yourself as American Flight 380 and tell them you have a faulty fuel pump in Number Two engine."

"Where are the terrorists?"

"Don't worry, they're here. By the way, you must also turn off your transponder. Now."

Ogonowski turned on the PA system.

"Ladies and gentlemen, we have experienced a slight difficulty with one of our fuel pumps and must land to have it checked. American is sorry for the delay. We'll have alternate transportation ready for you as soon as possible."

The gentleman smiled, nodding approvingly. A murmur of groans and complaints filtered into the cabin.

"One more thing. As soon as we touch down, proceed immediately to the military hangars at the north end of the airport. We have a team of agents there who will board the aircraft as soon as you can get the doors open."

Although Ogonowski sent no messages to New York ATC, he could hear the chatter and knew something was up. About seven minutes before they would land at Harrisburg, he heard that one of the World Trade Center towers was on fire, having been hit by a "commuter aircraft," as the rumor had it. Ahead of him the layout of Harrisburg Airport, faintly discernible in the distance, grew slowly in size. The aircraft banked and made its final approach. Unknown to Ogonowski, another Boeing 767 shadowed flight AA11, below and slightly behind them. It climbed, even as flight AA11 descended. More radio chatter revealed that aircraft had been ordered down all over the United States. Ogonowski would be the first of many emergency landings at Harrisburg International that day.

The 767 glided smoothly to touchdown, its air brakes howling. The aircraft slowly rolled to a crawl, then turned onto a taxiway that led to an Air National Guard hangar, where a man with orange batons waved them in. As soon as the flight crew got the doors open, one of the group of waiting officials rolled a large gangway to the open door and three agents dashed up the stairs. One of them had a bullhorn.

"Ladies and gentlemen. We must ask that you leave the aircraft immediately. Leave all personal belongings and carryon bags aboard the aircraft. This includes cellphones. Do not attempt any cellphone calls, as they could trigger any explosives on board. We'll begin evacuation from the front of the aircraft."

Dutifully, the passengers streamed from the aircraft in orderly fashion, making their way down the steep gangplank and joining a crowd that had formed around another official.

"Ladies and gentlemen. It is now safe to tell you that you have just escaped being hijacked by Arab terrorists. We will apprehend the suspects and search the aircraft for bombs and other dangers to public safety. Unfortunately, this procedure may take some time and we have no facilities for you here. We'll have to put you on another flight, as soon as it arrives. I realize that this is very inconvenient and we apologize. However, you can think of yourselves as among the luckiest people in America today."

As he spoke, two officials led a disheveled man in handcuffs down the gangplank. He had olive-colored skin and a dark beard. A murmur went up from the crowd.

"Where the hell did he come from?" muttered McGuinness. He had a feeling of unreality in the pit of his stomach. He felt nauseous.

By then, another aircraft, flight UA175, had landed and was now taxiing toward the same hangar. The officials herded the passengers into the hanger, where they were told to wait. Then they went to greet the second aircraft, where they repeated the procedure.

Tower personnel were of course aware of the two flights parked at the Air National Guard hangar. They were aware that the aircraft were being inspected by some kind of security team but, beyond that, they paid little heed to the operation. They were too busy coordinating some very busy airspace.

5.2 Swapping aircraft

At the New York air traffic control center rows of radar operators "pushing tin," as they call it, monitored flights into and out of New York airspace, talking to the pilots occasionally on their throat mikes. Each operator had several flights to monitor, a job that guaranteed one of the highest stress levels of any occupation in the travel industry.

The time was 8:37 in the morning. Operators were about to become aware that something was amiss in their airspace. We pick up the conversation between one of them (bold face) and the aircraft under his responsibility. (NYT 2001) My commentary within the transcript has been placed in square brackets.

"USA583 checking in at FL350."

"USA583 Roger."

"42-39 see the 823 FL350 reference that guy on left."

"I gave the FDX turns. Do what you want, reference the FDX."

" R49 310."

"FDX226 contact New York Center on 133.47. Good day."

"33.4 FDX3226 heavy."

"New York UAL 457."

"Sector 10 point out west of LRP 712 at FL410."

"Point out approved."

"UAL175 at FL310."

[The time was 8:40 am. United Airlines Flight 175 came on the air with some information to report.]

"UAL 175 New York center. Roger."

"New York do a favor. Were you asked to look for an aircraft, an American flight about about 8 or 9 o'clock 10 miles south bound last altitude 290? No one is sure where he is."

"Yeah, we talked about him on the last frequency. We spotted him when he was at our 3 o'clock position. He did appear to us to be at 29,000 feet. We're not picking him up on TCAS. I'll look again and see if we can spot him at 24."

"No, it looks like they shut off their transponder. That's why the question about it."

"New York UAL175 heavy."

"UAL 175 go ahead."

"We figured we'd wait to go to your center. We heard a suspicious transmission on our departure from BOS. Sounds like someone keyed the mike and said, 'Everyone stay in your seats.'"

O.K. I'll pass that along.

"It cut out." (UAL 175)

"IGN 93 line."

"Go ahead."

"UAL 175 just came on my frequency and he said he heard a suspicious transmission when they were leaving BOS: 'Everybody stay in your seats.' That's what he heard as the suspicious transmission, just to let you know."

[Then US Air Flight 583 called in.]

"Center, where do you place him in relation to 583 now?"

"He's off about 9 o'clock and about 20 miles. Looks like he's heading southbound but there's no transponder, no nothing, and no one's talking to him."

"Hello New York good morning DAL2315 passing 239 for 280."

"DAL2315 New York Center. Roger."

"New York center DAL2433 310."

"DAL2433 New York Center. Roger."

[Four minutes later the time was 8:46 and the mystery had not been solved. Flight 11 was flying an angular route south, then east. Other flights continued to converse with New York ATC.]

"Direct PTW DAL 1489 heavy."


"DAL2315 contact the New York Center on 134.6. Have a nice day."

"134.6 DAL2315."

"34.6 3-4-point 6."

"USA429 leveling off at 350."

I'm sorry, who was that?

"USA429 leveling at 350."

"USA429, New York Center roger."

[As we will shortly see, the radar operator lost track of Flight AA11, as evidenced by his queries of pilots in the area, as well as his failure to make any connection between the World Trade Center fire (about to be reported) and Flight AA11. It appears that the flight had simply been lost in the swarm of blips that crowded every screen at the New York ATC.]

"Anybody know what that smoke is in lower Manhattan?"

"I'm sorry, say again."

"A lot of smoke in lower manhattan."

"A lot of smoke in lower Manhattan?"

"Coming out of the top of the World Trade Center building, a major fire."

"And which was the one that just saw the major fire?"

"This is DAL1489 we see lower Manhattan. Looks like the World Trade Center on fire, but its hard to tell from here."

"DAL1489. Roger."

"Let us know if you hear any news down there."


"DAL 1043 cleared direct PTW."

"Direct PTW DAL 1043."

[At 8:51 am, the operator was still in touch with Flight 175, asking the pilot to change his transponder code.]

"UAL175 recycle transponder squawk code 1470."

"UAL175. New York."

[But at 8:52 am, things went wrong with Flight UAL175, as well.]

"UAL175 do you read New York?"

"DAL1489 do you read New York?"

"DAL1489. Go ahead."

"O.K. Just wanted to make sure you were reading New York. United, United 175. Do you read New York?"

"IGN on the 93 line. Kennedy."

"IGN on the 93 line East Texas."


"Do me a favor. See if UAL175 went back to your frequency."

"UAL 175?"


"He's not here. East Texas."

"10 — Do you see that UAL175 anywhere? And do me a favor. You see that target there on 3321 code at 335 climbing? Don't know who he is, but you got that USA 583. If you need to descent him down you can. Nobody. We may have a hijack. We have some problems over here right now."

"Oh you do?" [another operator]

"Yes, that may be real traffic. Nobody knows. I can't get a hold of UAL175 at all right now and I don't know where he went to."

[The transcript reveals a new aircraft with transponder code 3321. The aircraft has already climbed to 33,500 feet. This may have been the replacement aircraft.]

"UAL 175 New York."

"New York 583."

"USA583 go ahead."

"Yes. Getting reports over the radio of a commuter hitting the World Trade Center. Is that nordo [no radio] 76 [Boeing 767] still in the air?"

It is interesting that the initial report of the first WTC attack involved not a 757, but a smaller commuter aircraft. From that point on however, things got increasingly hectic at the New York ATC center. Operators glanced at the screen space centered on Manhattan and eastern New Jersey, trying to guess which aircraft was Flight 175.

On all screens there were often several aircraft without transponder codes. Some of these were local flights, mostly smaller aircraft. The presence of such blips would probably have made the radar operator's job much harder. Taking one's eye off a suspicious aircraft to check other aircraft in the area might make it impossible to be certain which aircraft it was when the operator glanced back. This, in any case, was apparently what happened.

5.3 The World Trade Center

It would have been an eerie experience to ride the 757 that we have called Flight 175-X. Walking the aisles, we would have seen the seats all stripped from the aircraft, the walls lined with fuel drums, like so many token passengers. Cables ran up the aisle to the cockpit, where a large black box sat on the floor, just in front of the control console. The pilots' seats were missing. Some of the cables fed into several openings in the console, others passed through openings in the floor into the aircraft's belly, where the antenna system communicated with a ground station.

At the ground station, an operator watched a color television monitor. On it, he could see the Manhattan skyline looming steadily larger. He adjusted the joystick slightly to the right, aiming for the south tower, then pushed the stick forward slightly. The aircraft slowly descended until it was level with the upper third of the still distant building. An ironic smile crossed the operator's face. This was not exactly the intended use of the Predator technology.

About a minute from impact, a steady crosswind that the operator had not taken into account had pushed the aircraft off course to the east, even as the tower loomed faster than he thought it would. He was going to miss! Damn. He pulled the joystick sharply to the left.

Just when the corner of the south tower was about to disappear from the screen , it swung back into view again, the building now appearing sharply tilted to the right. He saw several rows of windows. Close, then very close. In the last frame, he caught a glimpse of some office people staring from one of the windows in horror. Then the screen went blank. To think of how close he came to missing!

5.4 Back at the base

Under the operation Pearl scenario, the takedown of all four flights would be conducted in the same manner, flights UA93 and AA77, being no exceptions. By the time Flight UA93 arrived over Harrisburg, the alarm had been out for a good 20 minutes. Flights were coming down everywhere. Airport tower personnel, as well as those at all air traffic control centers, were simply overwhelmed. In this context, bringing flights UA93 and AA77 into Harrisburg were relatively simple and secure operations involving little more than switching to a new transponder number, landing and proceeding to the same processing area. The same cover story still worked, since it was not known at the time whether aircraft might be targeted, as well as buildings.

The swap of flight UA93-X for flight UA93 would have been far less exposed to radar than the swaps in the NY phase of the operation. As Flight UA93 descended into the radar shadow of the Susquehanna valley close to Harrisburg International, an executive jet rose out of the valley, below and immediately behind the aircraft. The swap would have been seamless, with Flight UA93 turning off its transponder about the same time that the pilot of Flight UA93-X turned his on. Flight UA93-X then turned north to follow an erratic path to the west as far as Cleveland before looping back to head for southern Pennsylvania.

The search for bombs on Flights AA11 and UA 175 may have already been completed by the time that Flight 93 touched down at 9:07 am. The officials in charge of the operation nevertheless had a good 20 minutes to search flight UA93 before hurriedly boarding all the passengers into the one aircraft, an operation that could have been carried out in 20 minutes.

As the passengers boarded Flight UA93, the officials held a special conference with pilot Jason Dahl and First Officer LeRoy Homer.

"Fellows, we've made a thorough check for bombs on board, and we're sure it's clean. Unfortunately, we have some problems with the other aircraft, so we're going to have to keep them grounded for the time being. We don't have proper facilities for all these people here, so we're going to have to ask you to take them all to Dulles where they can be looked after properly. We'll send all personal goods and luggage along on one of the the other aircraft, as soon as we have completed our work. We'll have to board the other passengers now, without delay. You will be picked up by a military escort aircraft as you leave. Please be sure to follow that aircraft and stay in communication with it. Frequency will be 118.7 MHz. all the way. Fly at the same level of 4000 feet. If it should happen to deviate from its flight path, it may be checking something out. Just stay on course for Dulles. Your escort will rejoin you soon enough."

Pilot and first officer nodded, then climbed the stairs, entered the cockpit and began the preflight check for the second time that morning. Meanwhile, passengers filed into the aircraft, urged on by the officials, until the aircraft was full. As it happened, flight 93 had just enough seats to accommodate the passengers of all four flights.

At 9:45 the 757 roared off the runway at Harrisburg and set course for Washington, even as a military-looking all-white aircraft rose from low altitude to fly off their port wing.

"This is your Escort Bravo One. We're not very fast, here." said the military pilot. "Reduce your airspeed to 400 knots and stay directly behind with minimal separation."

"I've seen that kind of aircraft before," said Homer.

"Yup. That's an A-10 Warthog," said Dahl. "And she's armed to the teeth. See the missiles under the wing?"

"Warthog? Funny name."

"Actually, it's called the Thunderbolt, but I guess everyone thinks the thing is too ugly to be called anything but a warthog."

5.5 The Crash at Shanksville

The two aircraft climbed out along the valley of the Susquehanna, then headed southwest along a succession of valleys, emerging at last into a large, relatively flat basin, partly forested and dotted with farms and villages. Ahead of them, the white aircraft, flight UA93-X, suddenly turned off and began circling around to the east, descending as it went.

Shanksville resident Susan Mcelwain watched the white aircraft pass directly over her minivan:

"It came right over me, I reckon just 40 or 50 feet above my van," she recalled. "It was so low I ducked instinctively. It was traveling real fast, but hardly made any sound. (UF93 2001)

"Then it disappeared behind some trees. A few seconds later I heard this great explosion and saw this fireball rise up over the trees, so I figured the jet had crashed. The ground really shook. So I dialed 911 and told them what happened . . . "

"There's no way I imagined this plane — it was so low it was virtually on top of me. It was white with no markings but it was definitely military, it just had that look. It had two rear engines, a big fin on the back like a spoiler on the back of a car and with two upright fins at the side. I haven't found one like it on the internet. It definitely wasn't one of those executive jets. The FBI came and talked to me and said there was no plane around."

The description of the mystery aircraft given by Ms Mcelwain happens to match only one military aircraft currently in use by the US armed forces, namely a (repainted) A-10 Thunderbolt, a heavily armed aircraft used in ground support roles. (McChord 2003) Several other witnesses saw the same aircraft, both before the crash and after it, circling the area. (Flight 93, 2001)

Two area residents, both quite close to the crash scene, heard missiles being fired. One, a Viet Nam veteran, was quite sure about what he had heard.

Mcelwain and many others heard one or two tremendous explosions rock the sky over Shanksville. Debris rained down for miles around. One engine landed nearly a mile from the alleged crash site. Body parts, luggage, scraps of metal, bits of in-flight magazine plummeted or fluttered to the ground a mile or more away.

The white aircraft turned, took one more pass, then headed back to its base of operations. Mcelwain called 911.

The Shanksville "crash" of Flight 93 presents us with a number of mysterious reports of a midair explosion (or explosions) as well as the presence of a white "mystery jet" seen in the area by many local residents.

The midair explosion was heard by virtually everyone in the area, of course. The debris field resulting from the explosion was apparently much more extensive than what would result from an ordinary crash, with all the debris within a narrow compass laterally to the incoming flight path. New Baltimore resident Melanie Hankinson, who lives some eight miles from the crash site, found paper debris from the aircraft, including remnants of United Airlines in-flight magazine, Hemispheres. Other debris, including body parts, were scattered over a space of miles. One of the engines were found a "considerable distance from the crash site," according to State Police Major Lyle Szupinka.

Shanksville Mayor, Earnest Stuhl, has stated that at least two area residents, both living within a few hundred yards of the debris field, heard missiles being fired. One of the witnesses, a Viet Nam veteran, had heard missiles fired from aircraft many times during his tour of duty and claimed that it could not be anything else.

5.6 The Attack on the Pentagon

About the time that Flight AA11-X struck the north tower of the World Trade Center in New York, Flight AA77-X took over from Flight AA77. Like Flight UA93, Flight AA77 dropped into one of the numerous valleys that run the length of the Alleghenies, possibly the valley of the Shenandoah River. Meanwhile, Flight AA77-X, an executive jet, fled westward across West Virginia before looping back, close to the border of southern Ohio. At this point, the pilot turned off his transponder and headed straight for Washington, DC.

By 9:30 am Flight AA77-X was already over Virginia, closing rapidly on the capital. As it approached the Pentagon from the west, another smaller aircraft, possibly a cruise missile, came into the Pentagon from the southwest. It came very fast. Flight AA77-X banked sharply to pass over the Pentagon from the same direction, then flew off to its base. Although visible on local radar as an overflight, it was confused with the incoming missile, which would have been visible as a second blip. Operators would have been led to assume that the second blip represented the overflight.

The small military aircraft (or missile) slammed into the lower half of the 80-foot high wall of the Pentagon, its fuselage punching a hole in the two-foot thick limestone block wall.

5.7 Disposal

Getting rid of the original aircraft was trickier than one might suppose. One could not simply wash off the paint with an acid scrub and sell the aircraft to a third world country. Nor could one break the aircraft up and sell the parts. Indeed the parts, thousands of them, were all stamped with serial numbers that were registered to their respective aircraft. They could be traced. For this reason, it would have been much cleaner to dump the aircraft in the Atlantic Ocean.

Perhaps it was not until nightfall of September 11 that the disposal operation started. By then each aircraft had been fitted with slave technology. The master aircraft had already flown out over the Atlantic, the signal from the data bus monitor having been transmitted back to shore and recorded. It would then have been a simple matter to replay the tape to each of the three "non-existent" aircraft at half-hour intervals. Each aircraft would have gone through exactly the same motions as the master aircraft, continuing its flight out over the Atlantic Ocean — until the implanted bomb destroyed it. Under the Operation Pearl scenario, the three aircraft ended up in pretty much the same state as the Bush-Cheney scenario alleges. The locations are quite different, however.

Inspiration for the electronic tow technology came from the eyewitness account of two aircraft sighted by a New Jersey resident and his wife (names witheld by request).

"Several days before 911, my wife and I were walking on Long Beach Island. It was late in the afternoon when I looked out over the ocean and saw these two passenger jets flying toward us, due west. They were flying amazingly low and amazingly slow. I was amazed to see these two jets were flying closely behind the other [sic], nose to tail, and what was most amazing was that they were perfectly spaced, about fifty feet apart, with absolutely no fluctuations in their spacing. It looked just like one plane was towing the other. They flew right over our heads, and I watched them as they flew westward."

Under the operation Pearl scenario, the strollers witnessed a final test of the master/slave control system.

6 The Evidence Filter

We are now in a position to review the evidence and its relationship to the Operation Pearl scenario described above. Below each item in the original checklist, I have placed a brief explanation of the relationship.

Suspicious circumstances

  1. Four of the named hijackers were not in the United States. The alleged hijackers were not on the aircraft, in any case. Their names may have been selected from a list of lapsed or stolen passports.
  2. The WTC towers collapsed without adequate heat stress. The lack of passenger corpses, luggage, etc, had to be concealed by burial.
  3. Smaller aircraft accompanied Flights AA77 and UA93. Surrogate aircraft were used as substitutes for the originals.
  4. Most of the alleged hijackers were rather poor pilots. The alleged hijackers were not aboard the aircraft, in any case.
  5. Evidence of alleged hijackers developed too quickly. Evidence was planted in order to have the story develop quickly.
  6. Westward excursion of Flights UA93 and AA77 are inexplicable as terrorists hurrying to targets. The excursions gave time to load all the pasengers onto Flight 93.


  1. The US Air Force failed to intercept any of the flights. No interceptors were deployed since their pilots would have reported the substitute aircraft.
  2. The hijackers' names did not show up on passenger lists. The hijackers were not aboard the aircraft.
  3. The hijackers' faces did not appear on boarding gate videos. The hijackers were not aboard the aircraft.
  4. Black boxes were missing from all but one flight. Black boxes were not present on attacking aircraft


  1. Aircraft striking the Pentagon was not a large passenger aircraft. Flight AA77 did not strike the Pentagon.
  2. Cellphone calls made by passengers were highly unlikely to impossible. Flight UA93 was not in the air when most of the alleged calls were made.

Expanded timeline for Operation Pearl

7:59 am UA11 takes off from Boston's Logan Airport
8:14 am UA175 takes off from Boston's Logan Airport
8:16 am First deviation of AA11 north of Albany, NY
8:20 am AA77 takes off from Washington's Dulles Airport
8:20 am AA11 transponder turned off
8:30 am First swap: Flight AA11-X takes over, transponder off
8:35 am Beginning of NY ATC transcript
8:40 am UA175 transponder is turned off
8:42 am UA93 takes off from Newark, NJ
First deviation of UA175 over northern NJ
8:46 am Second swap: Flight AA77X takes over, same t-code
8:46 am AA11-X strikes north tower of WTC
Nationwide alert begins
8:53 am Third swap: Flight UA175X takes over, transponder off
AA11 lands at Harrisburg
8:54 am End of NY ATC transcript
8:55 am AA77X transponder is turned off
9:02 am UA175X strikes south tower of WTC
UA175 lands at Harrisburg
Fourth swap: Flight UA93X replaces UA93
9:07 am UA93 lands at Harrisburg
9:09 am AA77 lands at Harrisburg
9:37 am AA77X overflies the Pentagon, aircraft or explosion at Wedge 1
9:45 am UA93 takes off from Harrisburg
10:06 am UA93 crashes near Shanksville, PA

[map goes here]

Footnote 1: The plot of the movie, set in a decaying future New York ruled by warlords, involves the rescue of the President of the United States who is being held for ransom. Snake Plissken (played by Kurt Russel) is released from jail by authorities eager to use his talents to rescue the President.


(USA Today 2001) USA Today. 2000. Weapons of destruction. Accessed from on July 5, 2003.

(Dewdney 2002) Ghost riders in the Sky. Feral News. Retrieved from May 15, 2003.

(Flight 93, 2001) How did Flight 93 crash? Retrieved from May 20, 2003. Note: this site uses mostly local and national media sources.

(McChord, 2003) A-10 Thunderbolt. McChord Air Museum. Retrieved from

(NYT 2001) The New York Times. October 16, 2001, Transcript of United Airlines Flight 175. Retrieved from July 4, 2003.

(Ostrovsky & Hoy, 1990) Hoy C, Ostrovsky V. 1990. By Way of Deception. Toronto, Canada: Stoddart.

(Serendipity 2002)

(SPC 2000) FTS Flight termination system. 2000. System Planning Corporation, Langley, VA. Retrieved from May 17 2003. See (flight termination system) and also (command transmitter system)

(Spitzer 2000) Spitzer, C. R. 2000. Digital Avionics Systems: principles and practices. The Blackburn Press (McGraw-Hill), Caldwell, NJ.

(UF93 2001) United Flight 93 Crash Theory Home Page. 2001. How did Flight 93 Crash? Retrieved from June 10, 2003.

(USAF no date) RQ-1 Predator unmanned aerial vehicle. United States Air Force Fact Sheet. Aeronautical Systems Center, USAF, Langley, VA. No date on document. Retrieved from May 18 2003.

(USAF 98) Global Hawk: U. S. Airforce Fact Sheet. Global Hawk. Aeronautical Systems Center. USAF Langley, VA. Retrieved July 4 2003 from


A: The Basic Timeline

(All times are ante meridian or am, EDT)

Flight Departure Deviation Transponder Hit
American 11 7:59 am 8:16 am 8:20 am 8:46 am
United 175 8:14 am 8:42 am 8:40 am 9:02 am
American 77 8:20 am 8:46 am 8:55 am 9:37 am
United 93 8:42 am 9:36 am 9:40 am 10:06 am

B: Table of aircraft

Flight no Equipment Airport On board
Flight 11 Boeing 767 Boston Logan 81 passengers, 11 crew
Flight 175 Boeing 767 Boston Logan 56 passengers, 9 crew
Flight 77 Boeing 757 Wash. Dulles 58 passengers, 6 crew
Flight 93 Boeing 757 Newark Intn'l 30 passengers, 7 crew

C: Estimates of equipment and personnel used in Operation Pearl

The following lists represent the core requirements in equipment and personnel required to execute Operation Pearl. Additional equipment as well as operatives playing minor roles are not included. Also not included are the operatives running "Operation Footprint," the flight training program for approximately ten Arabs from a variety of middle eastern countries.

  • 1 Boeing 767 fitted with remote guidance systems
  • 3 Executive-sized jet aircraft, one fitted with a remote guidance system
  • 1 A-10 Thunderbolt
2 agents on each of four aircraft 8
10 agents at the base of operations 10
4 agents to set up WTC demolition explosives 4
2 agents as flight crew on substitute or escort aircraft 6
4 agents as technicians to install RC controls
  (also to act as remote pilots)

This number is certainly an underestimate, but easily mustered by any large intelligence organization. Under the Operation Pearl scenario, the most likely perpetrator would be Mossad, Israel's spy agency. An arm's-length relationship with the Bush administration, with neocon elements acting as go-betweens, would enable Rumsfeld, Bush and other members of the US administration to disclaim any "specific" knowledge of a forthcoming attack. (See Ostrovsky and Hoy, 1990.)

© 2003 A. K. Dewdney

This article was originally published on Professor Dewdney's website
On 2003-09-08 went down (for reasons unknown) but was back on line on 2003-09-10.

This article (with some links to pages on changed to local links)
was published on Serendipity on 2003-09-09.

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