Code 7500

Die Pilotenseite

Das Aeronautical Information Manual (AIM), Richtlinie der FAA für Piloten, hier auf dem Stand von Juli 2001, definiert im sechsten Kapitel, wie sich ein Pilot im Fall einer Entführung zu verhalten habe.

6-3-4. Special Emergency (Air Piracy)

a. A special emergency is a condition of air piracy, or other hostile act by a person(s) aboard an aircraft, which threatens the safety of the aircraft or its passengers.
b. The pilot of an aircraft reporting a special emergency condition should:
1. If circumstances permit, apply distress or urgency radio-telephony procedures. Include the details of the special emergency.
2. If circumstances do not permit the use of prescribed distress or urgency procedures, transmit:
(a) On the air/ground frequency in use at the time.
(b) As many as possible of the following elements spoken distinctly and in the following order:
(1) Name of the station addressed (time and circumstances permitting).
(2) The identification of the aircraft and present position.
(3) The nature of the special emergency condition and pilot intentions (circumstances permitting).
(4) If unable to provide this information, use code words and/or transponder as follows: state “TRANSPONDER SEVEN FIVE ZERO ZERO.” Meaning: “I am being hijacked/forced to a new destination;” and/or use Transponder Setting MODE 3/A, Code 7500.
NOTE-
Code 7500 will never be assigned by ATC without prior notification from the pilot that the aircraft is being subjected to unlawful interference. The pilot should refuse the assignment of Code 7500 in any other situation and inform the controller accordingly. Code 7500 will trigger the special emergency indicator in all radar ATC facilities.
c. Air traffic controllers will acknowledge and confirm receipt of transponder Code 7500 by asking the pilot to verify it. If the aircraft is not being subjected to unlawful interference, the pilot should respond to the query by broadcasting in the clear that the aircraft is not being subjected to unlawful interference. Upon receipt of this information, the controller will request the pilot to verify the code selection depicted in the code selector windows in the transponder control panel and change the code to the appropriate setting. If the pilot replies in the affirmative or does not reply, the controller will not ask further questions but will flight follow, respond to pilot requests and notify appropriate authorities.
d. If it is possible to do so without jeopardizing the safety of the flight, the pilot of a hijacked passenger aircraft, after departing from the cleared routing over which the aircraft was operating, will attempt to do one or more of the following things, insofar as circumstances may permit:
1. Maintain a true airspeed of no more than 400 knots, and preferably an altitude of between 10,000 and 25,000 feet.
2. Fly a course toward the destination which the hijacker has announced.
e. If these procedures result in either radio contact or air intercept, the pilot will attempt to comply with any instructions received which may direct the aircraft to an appropriate landing field.

Der Pilot soll demnach nach Möglichkeit die Prozeduren für einen Notfall befolgen; sollte dies nicht möglich sein, soll er zumindest einige Basisdaten zur Notlage an die Flugüberwachung durchgeben; sollte dies nicht möglich sein, soll er den Transpondercode 7500 senden. Die Anweisungen setzen voraus, dass zumindest kurz Zeit für Entscheidungen bliebe und der Pilot selbst das entführte Flugzeug fliegt („Maintain a true airspeed of no more than 400 knots …“). Bis zum 11. September 2001 hatte es noch nie einen Fall gegeben, in dem das anders war.
Das AIM hat damit eine implizite Prämisse: Dass nicht den Piloten des Flugzeugs mit Entführungsbeginn augenblicklich Gewalt angetan wird. Diese Prämisse spricht auch aus den 9/11 eher schwachen Vorkehrungen gegen ein unbefugtes Eindringen ins Cockpit: Schlüssel für die Flugbegleiter und bewusst schwache Cockpittüren, die mit physischem Einsatz einfach zu öffnen waren, um dem Piloten ein leichtes Entkommen im Notfall zu ermöglichen (Details).

Diese Prämisse wurde den Piloten der entführten Flugzeuge 9/11 zum Verhängnis. Sobald die Entführer sich in Sekundenschnelle mit Gewalt oder per Schlüssel Zugang zum Cockpit verschafft hatten, kämpften die Piloten um ihren Platz und um ihr Leben.
Einem der Piloten von UA 93 gelang es, während des Eindringens der Attentäter („Get out of here“) gemäß dem „distress“-Protokoll in kurzem Abstand zweimal in hörbarer Not einen „Mayday“-Ruf abzusetzen, der im Funkverkehr des Tages aufgenommen wurde – ein verstörendes Zeitzeugnis der im Cockpit ausgeübten Gewalt.

Das Auseinanderfallen von der sich in diesen Richtlinien spiegelnden Erwartungshaltung – traditionelle Entführung – und Realität – die Ermordung der Piloten, mindestens ihre gewaltsame Entfernung aus dem Cockpit – erklärt, warum die Entführungsanzeichen von den Piloten selbst so spärlich sind. In der unerwarteten Gewaltsituation tippte keiner der Piloten den Transpondercode 7500 ein, wie aus den Radardaten, FDR-Daten und Interviews mit Beteiligten hervorgeht.

Die ATC-Seite

Das für Air Traffic Controller zum Zeitpunkt der 9/11-Anschläge gültige Protokoll sah für eine Flugzeugentführung den Code 7500 als primäres Erkennungsmerkmal vor:

10-2-6. HIJACKED AIRCRAFT
When you observe a Mode 3/A Code 7500, do the following: […]

Die zugrunde liegende Annahme ist auch hier, dass der Pilot einer entführten Maschine, wenn er schon (bedrängt vom Entführer) keinen Kontakt zur ATC aufnehmen dürfe, immerhin in der Lage wäre, die Entführung über den Transponder (oder einen verbalen Code) mitzuteilen. Hierfür wird vorausgesetzt, dass im Falle einer Entführung der Pilot selbst das Flugzeug fliegt.

Angestellte der beteiligten ARTCCs ZBW und ZNY bestätigen, dass Entführungserkennung im ATC-Bereich bis 9/11 auf den 7500-Code oder eine verbale Bestätigung angelegt war:

Specifically, Air Traffic Controllers are taught that a hijack would include a covert sign from the cockpit, either use of the transponder code 7500, which flashes “HIJACK” on the data block for the flight on the TMU (traffic monitoring unit), or the pilot would have used covert language (the word “trip” to describe the airplane’s course) to signal the ATC. In simulated hijack exercises the pilot would be in contact with the ATC, and they would be able to verbally confirm “7500″ for a hijack, “7600″ for a malfunctioning transponder, and “7700″ for an emergency.

Terry Biggio, Operations Manager Areas A and D im ZBW

Regarding hijack procedures pre-9/11 Dean noted that the ATC is trained to respond to signals from the cockpit – either direct verbal confirmation, the confirmation of squawking the 7500 transponder code, or the use of code words – by relaying the information to the supervisor.

William Dean, Traffic Management Unit Specialist im ZBW

Alfaro commented that his hijack procedure prior to the events of 9/11 was to verify the hijack with the pilot via the hijack code, “7500″, and to notify his supervisor that a hijack was in progress. The standard procedure was not to make inquiries with the pilot in the cockpit to avoid escalating events.

Charles Alfaro, Operational Supervisor for Area C im ZNY

Training on Dynamic Simulations involves airplanes that squawk hijack code 7500, inferring that the airliner pilot is in control of the aircraft. Bottiglia continued his point by noting that controllers were never presented with a scenario or practice exercise that was more challenging than this. The procedure that he had learned was 1) to see the “hijack” warning flash on the scope; 2) to verify with the pilot that he is squawking 7500″; and 3) then to tell the supervisor for the area.

David Bottiglia, ATC im ZNY

Prior to 9-11, air traffic controllers usually detected hijacked aircraft because the pilot would squawk code 7500 (the “hijack code”) on his transponder. Controllers and supervisors were trained to verify the hijack code with the pilot. Today, the information regarding hijack codes is not well protected.

Kevin Delaney, Supervisor of the Quality Assurance Office im ZNY

Dowis commented that based on past ATC experience it was an institutional assumption that hijacked aircraft would land and make demands. Controllers, according to Dowis, are specifically taught to look for the 7500 hijack code, and to inform their CIC or area supervisor.

Evanna Dowis, ATC im ZNY

Prior 9/11 – as ATC would detect a hijack by 7500, by verbal or by the code word.

Peter McCloskey, Traffic Management Coordinator im ZNY

Merced informed Commission staff that prior to 9/11 he would have expected the pilot of a hijacked aircraft to covertly communicate the situation by using a hijack transponder code (7500) or through a verbal code.

Mark Merced, ATC im ZNY

Palmieri explained that pre-9/11 an air traffic controller was trained to identify and respond to hijack scenarios in very specific ways. This training included identifying the hijack Code 7500, or using a covert verbal confirmation of the hijack from pilot. He noted that all these indications are from the flight crew itself; the indications are not from observations made by the controllers based on the path or status of a flight. Palmieri noted that a plane with unusual characteristics does imply to an observant controller that there is a problem with the pilot or the airplane, or that there is an emergency situation with passenger; but not that there is an ongoing hijack.

Anthony Palmieri, ATC im ZNY

Prior to 9/11, if a hijacked flight is on the ground the pilot signals that the flight in an ongoing hijack by putting the aircraft’s flaps down. If the pilot is speaking on frequency the pilot can use the term “trip” to signal the hijack to the controller. If the flight is in the air the pilot may also squawk the hijack notification frequency of “7500″.

Martin Rosenberg, TMU Supervisor im ZNY

Pre 9-11 controllers would receive communication from the pilot about the hijack—code words or a specific transponder code. Neither of those things happened on 9-11.

Paul Thumser, Operations Supervisor im ZNY

Die Entführungsidentifikation war deshalb von analytischer Arbeit der Fluglotsen abhängig, die im Briefing des Boston Center (ZBW) beschrieben wird:

Determining a hijack. No one factor or combination of factors that day, other than the cockpit communications, definitely led Center personnel to a hijacking awareness. There are three such factors.
Loss of Radio Contact.
This phenomenon was common, to the point of being notorious. Pilots and crews were simply lax in maintaining contact. One interviewee made sure we understood the commonly misunderstood acronym “NORDO.” That means “no radio” in the literal sense that the aircraft’s radio(s) are not working. It is in that sense that controller 38R is captured on tape early in the AAll story designating AAll “nordo,” implying that the pilot is in control and unable to communicate. That is different from an aircraft with a working radio, but deliberately not communicating. The term for that, Staffwas told, is “NORAK,” (Ph)
Loss of Transponder. This phenomenon is much rarer, but not in-and-ofitself, alarming. Controllers routinely ask the affected plane to “recycle your transponder.” [That is the protocol used with UA175 by New York Center controllers.] Controllers generally agreed that transponder loss would be reported to the supervisor. The combination of “nordo” and transponder loss is highly unusual and many controllers had never experienced that combination. According to Mr. Biggio that combination is a sign of major equipment malfunction and at that point in the flight of AA 11 would not have triggered any notion of a hijack.
Course Deviation. One controller, a supervisor on duty that day as a radar associate to complete monthly qualification requirements, citied minor course deviation-AAII failure to climb to 35000 feet-as an additional warning sign. There was no consensus on that point, but all controllers agreed that the combination of “nordo,” transponder loss, and significant course deviation-the AA 11 turn to the south-was serious. However, Mr. Biggio on that point said that given a major equipment malfunction what might be happening was a pilot turning to land at a “heavy” capable airport. One controller supported that thesis, describing a “heavy” pilot as one who would try to land at Kennedy, vice elsewhere. A “heavy” aircraft is a term used by FAA controllers to describe a large aircraft such as a 747/757/767. Centerpersonnel who observed the turn south also observed a unusually rapid rate of progress, indicatively of a pilot who wanted to get somewhere in a hurry.
The Intervening Variable, Unusual Cockpit Communications. After AA 11 lost its transponder and just before it made a significant course deviation to the south, unusual communications of unknown source were heard on the AA 11 assigned frequency of controller 46R. It was quite clear to the controller that he had a problem and he immediately and loudly made that fact known. In a rapid sequence of events a quality assurance staff member, Bob Jones, personally went to the basement and reran the tapes and made the call that the voice said “we have some planes.” Mr. Jones’ accident file timeline will provide the exact time he communicated that fact to the watch desk and to Mr. Biggio. The OMIC log shows that Biggio declared a hijack, based on cockpit communications at 0825 EDT. That time appears to staff to be the time of the original communication itself and not the time that Biggio was notified by Jones. The accident file log will be determining factor.

Beteiligte der ARTCCs ZBW und ZNY kommentieren diese Merkmale entsprechend häufig (Ausnahmen: Dowis und Kurz) ohne Entführungsassoziationen:

According to Biggio, prior to 9/11, an airplane that had gone NORDO (no radio communication) was a frequent occurence. An airplane that lost transponder was relatively infrequent, but not unheard of. An airplane that had seriously deviated from ist course was indicative of a serious mechanical problem. Biggio and never experienced such a serious deviation before as was the case with American Air 11. The combination of the three factors-NaRDO, no transponder, course deviation–when applied to AA 11, were enough for Biggio to deem it necessary to contact ROC. But, without the threatening communication from the cockpit, he doubts AA 11 would have been recognized or labeled a hijack.

Terry Biggio, TMU Operations Manager im ZBW

Bueno explained that he understood normal procedure for a NORAC airplane was to check the NAV 80, try to raise the aircraft by various means (check previous transponder frequency, use AIR Inc., notify the aircraft’s company, ask other aircrafts to try and raise the NORDO airplane), but noted that although prior to 9/11 it was usual for pilots to be inattentive to ATCs at times, and that often there were 5 to 20 minute lapses in communication, the combination of circumstance (NORAC, no transponder, serious deviation off course) was infrequent. Despite this it was still unusual to call this to the attention of the “aisle supervisor” (area supervisor).
Bueno stated that prior to 9/11, a hijack would be predicted as a flight to Cuba or a ransom demand, but not as an act of terrorism. He also noted that with AA11, until the threatening cockpit communication was confirmed, predominately the Boston Center staff was concerned the place had experienced serious mechanical or electrical failure. He noted that there was an occurrence of this sort involving a generator malfunction post- 9111, and it was addressed immediately.
According to Bueno, the key that alarmed Boston Center over AA 11 before the threatening communication was the hard southern tum. The southbound course combined with a dropping altitude had already been reason enough for Terry Biggio to call for an immediate “ground stop” in the Sparta/Carmella traffic corridor. Once Bob Jones communicated the tape’s content to the TMU, Biggio informed ROC, WOC and New York Center of the necessity of an immediate ground stop at Logan.

Daniel Bueno, Traffic Management Supervisor im ZBW

At first, with only three factors, NORDO, no transponder and serious course deviation Cooper thought AA11 had experienced serious electrical damage. But after the hard left tum and the confirmation of a hijack through the cockpit communication, there was no doubt in Cooper’s mind.

Joseph Cooper, Traffic Management Unit Coordinator im ZBW

Dean stated that NORDO wasn’t very unusual prior to 9/11, but that no transponder signal was. Shirley Kula informed Dean that the last known altitude for AAl1 was FL 290, but Dean does not recall if the flight was off course yet at this point. He assumed though that since Kingston was informed the flight was of course.
Dean’s stated that lost transponders, though rare, can be mainly associated with older military aircraft. He believes he has seen it happen with commercial airlines five or six times in the course of his career. He has never seen an aircraft with no transponder, NORDO and with a serious deviation from course.
Pre 9111 Dean noted the standard procedure for NORDO was to operate off of common sense by checking the frequency of the plane’s previous sector, then attempting to contact the plane through company or through AirInc. Dean stated that approximately 80% of airspace users subscribe to AirInc.
Regarding transponder loss, Dean noted the ATC will request the crew recycle the transponder. Dean stated that a primary target is difficult to track, and that for a primary target to enter another center’s airspace it must have permission. When AA 11 went into ZNY airspace, ZNY wanted to know who had given it permission. When tagging a primary, Dean explained that the ATC must manually select the primary target, and associate a data block with that target.

William Dean, Traffic Management Unit Specialist im ZBW

Hartling does not remember a single time in his years with the FAA, nor in his time with the military, in which he controlled an aircraft with no radio communications, no transponder and was seriously off course.

John Hartling, ATC im ZBW

Kula instructed Ron Smith to call all vertical airspace under Sector 22 for AA11, and once AA 11 took the hard southern turn Kula input the change in route to inform other ATCs there was an airplane that may cross the paths of their air traffic.
Kula noted that it was at this point at which she became extremely concerned for AA11. She noted that though it was usual to have a NORAC (no radio communication) airplane in that sector, the serious course deviation and unsure altitude were dangerous factors for the other air traffic traveling through Boston Center.
In efforts to determine AA11 ‘s altitude, Kula asked a Delta flight to visually check AA 11′ s altitude. The Delta flight reported approximately FL 290.

Shirley Kula, Operations Supervisor im ZBW

Martens acknowledged that NORDO aircraft were extremely common prior to 9/11, and mostly when a plane is on the wrong transponder frequency the pilot would come back to the correct frequency within a few minutes. Martens noted that most major air carriers make sure their aircraft have two transponders, and so a plane that loses all transponder broadcast without pilot communication is a situation that warrants concern within approximately thirty seconds. Martens believed AA 11 was experiencing serious mechanical and/or electrical failure.

Brazilino Martens, ATC im ZBW

Until the threatening communication was confirmed, Schippani believed AA11 had experienced severe electrical or mechanical difficulty. Once the threatening conversation had been confirmed, and AA 11 took a southbound course, Schippani believed AA 11 was hijacked and headed for a landing at Kennedy or Cuba.

Jon Schippani, Operational Supervisor in Charge im ZBW

Alfaro explained to Commission staff that aircraft routinely are NORDO (no communications with controllers), and that there are various methods to get in touch with the aircraft. Further; Alfaro explained that it was not unusual for an aircraft to be out of communications for five or six minutes before a controller regained contact. However, controllers would inform supervisors immediately about the situation. Alfaro’s estimates and comments were based on 23 years experience.
Alfaro commented that a lost transponder incident averaged in frequency at about once a month. He considered it routine to lose a transponder and noted that it was not something to be alarmed about. The protocol was for a controller to ask the pilot to recycle the transponder. According to Alfaro, when the pilot recycled the transponder, in most circumstance the transponder signal would be restored.
The combination of a NORDO condition and a lost transponder was infrequent; according to Alfaro this occurred more than once a year but was still extremely infrequent. The combination of NORDO, a lost transponder and a serious course deviation was very rare.

Charles Alfaro, Operations Supervisor im ZNY

Pre 9-11 she had never heard of anything like what happened that day. Planes out of communication, NORDO, happened all the time and still happens but a little less. In the past two years the pilots have gotten better.
Loss of transponder would happen relatively often. Sometimes planes switch codes relatively regularly. The procedure is to ask the pilot to recycle. This is a non-urgent procedure if the controller is talking to airplane. Never in her career had both loss of communications and loss of transponder happened at the same time. She had also experienced course deviations, but never all three factors together.

Lorraine Barrett, ATC im ZNY

Bottiglia noted that despite the Coast track and lack of communication he did not think anything was really going wrong with UAL 175. According to him, sometimes pilots “just don’t listen”. The mind set at the time was controllers very rarely considered a lack of a pilot immediately communicating back to them as a problem.
Normally a pilot is probably ‘just doing something more important”. Pre-91l1 the actions of UAL 175 were not unusual; and it was not unusual for transponders to change code during a flight. Bottiglia checked his frequency to see if it was still working – a lost transponder code could also be a technical problem at the controller end.

David Bottiglia, ATC im ZNY

Prior to 9-11, Delaney would have associated an electrical or mechanical failure with an aircraft that had deviated significantly from its intended course, lost its transponder signal and radio communications. In his opinion, a drastic deviation in an aircraft’s course does not necessarily translate in the mind of a controller to the possibility of a hijack because a pilot without a functioning transponder may not know exactly what direction his plane is headed in. Delaney said the thought of a “hijack” would eventually “creep” back into the controller’s thought process. Delaney opined that knowledge of the threatening cockpit communications overheard by the Boston ATC and the UAL 175 pilot would certainly lead one to conclude that AA 11 had been hijacked.
However, Delaney stated the information ZNY received from ZBW was “sketchy” regarding the content of the hijacker’s statements in the cockpit of AA 11.
Kevin Delaney, Supervisor of the ZNY Quality Assurance Office Dowis explained that the radio frequency changes each time an aircraft enters a new sector. She noted that, at .times, pilots get confused when they hear radio frequency changes intended for another plane.
Equipment failure (loss of transponder) is not frequent. According to Dowis, an aircraft’s loss of transponder rarely occurs. Dowis also commented that an aircraft’s deviation from course is unusual and infrequent.
Dowis stated that the loss of both radio communication and transponder in her view would indicate equipment failure and an imminent aircraft crash. Even prior to 9/11, when an aircraft deviates significantly from its course in addition to the loss of radio communication and transponder, Dowis said she would immediately think a hijack had occurred.

Evanna Dowis, ATC im ZNY

According to Kurz, prior to 9-11, he would have concluded that an aircraft with no transponder signal, no radio communications and traveling significantly off course had been hijacked. Therefore, he would have assumed that AA 11 was hijacked without the information he received from Boston Center. Kurz first thought AA 11 was headed over the Atlantic Ocean towards South America. He believed it was a traditional hijacking whereby the pilot would seek ransom or political asylum. Kurz stated he had no reason to think otherwise since, prior to 9-11, he had never heard of a scenario whereby terrorists would use aircraft as weapons of mass destruction.

James Kurz, TMU coordinator im ZNY

It is virtually impossible to detect a hijack without the pilot telling you since so many other things are taking place. Personally, if they are going off course, he is “going to ask ” – “do you realize you are off course?” He has not received any training to be more aware in a formal sense.

Peter McCloskey, Traffic Management Coordinator im ZNY

Merced noted that prior to 9/11 it was often that an aircraft would not be in constant contact with the air traffic controller, and that this was no reason to assume the aircraft was undergoing a hijack. He further noted that a lost transponder signal does happen, but prior to 9/11 an air traffic controller would have approached the problem thinking that there was something electrical wrong with the aircraft. Once the aircraft deviates from course, Merced would have thought that there was an emergency and the pilot was headed for the nearest airport.

Mark Merced, ATC im ZNY

Palmieri explained that pre-9/11 an air traffic controller was trained to identify and respond to hijack scenarios in very specific ways. This training included identifying the hijack Code 7500, or using a covert verbal confirmation of the hijack from pilot. He noted that all these indications are from the flight crew itself; the indications are not from observations made by the controllers based on the path or status of a flight. Palmieri noted that a plane with unusual characteristics does imply to an observant controller that there is a problem with the pilot or the airplane, or that there is an emergency situation with passenger; but not that there is an ongoing hijack.

Anthony Palmieri, ATC im ZNY

Prior to 9/11, if the flight was not communicating (Nordo) and had its transponder off Rosenberg would still not refer to the flight as a hijack. If the flight had a significant deviation from course Rosenberg would consider it an emergency condition. Rosenberg believes ZBW did not know if AA 11 was experiencing a mechanical emergency or a hijack, and Rosenberg passed this information to McCormack.

Martin Rosenberg, TMU supervisor im ZNY

Other ways to detect or suspect a hijack–not talking to ATC and/or extremely off course. Without communications nothing could be confirmed, however.
Pre 9-11 the controller would receive the communication – pilot reports hijack – get the information and report to the area supervisor. The area supervisor would report to the watch desk and the OMIC (Operations Manager in Charge) would follow up. He doesn’t believe anyone below the OMIC would do the follow up.

Paul Thumser, Operations Supervisor im ZNY

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