Fifty years ago, the Popular Front for the Liberation of Palestine (PFLP), executed a terrorist attack against civil aviation, unprecedented at the time in terms of skill, coordination and media attention. The simultaneous hijacking of four airliners and the ensuing hostage crisis kept the world on edge. Dr. Jonathan Zimmerli examines archival sources of the early 1970s in order to assess why airports and airlines were unprepared for these terrorist attacks and questions whether we ever actually learned the lessons of the infamous ‘Skyjack Sunday’.
In the late 1960s, skyjackings, as they were called in the United States, were almost as common as bank robberies. With an average of one hijacking per week, television and news agencies broadcasted live sensational stories of love sick, disenchanted or bankrupt hijackers demanding money or simply a flight to Cuba. Airlines tried to cope with this avalanche of hijackings by downplaying them as minor incidents, instructing their pilots to comply with all demands while equipping the crews with landing charts for Havana International Airport.
In 1969, the Nixon Administration was fed up with the state of affairs and demanded a response. While the Federal Aviation Administration (FAA) seemed paralysed, various senators proposed that airports should start to utilise X-ray machines and metal detectors, techniques already applied at maximum-security prisons, for screening passengers’ baggage. In fact, throughout the 1960s passengers were not screened due to the airline industry’s fear of losing customers in the competitive domestic market; newly hired and highly paid lobbyists were able to ensure that legislators eventually dropped the implementation of a nationwide screening requirement for passengers.
“…the PFLP hijacked another plane, a BOAC Super VC-10 en route from Mumbai to London via Bahrain, to land on Zarqa’s desert airstrip…”
Shortly after the US Congress had been debating the implementation of potential security controls, the threat against civil aviation intensified in Europe. The first attack occurred in Rome, where three members of the PFLP, a terrorist group founded by George Habash after the Six-Day War, hijacked El Al Flight 426. They wounded the co-pilot and made a televised landing in Algiers. Additional ground attacks against two El Al flights in Athens and Zurich resulted in El Al raising its security measures to unprecedented levels, forcing the PFLP to shift its attention towards western airlines. Two subsequent hijackings targeted US air carriers, while, in February 1970, an improvised explosive device detonated in the aft compartment of Swissair Flight 330 en route to Tel Aviv, crashing only two thousand metres away from a nuclear plant, killing all passengers aboard.
In the late summer of 1970, the threat of Palestinian terrorist attacks was pervasive, especially on flights departing from European airports. El Al had reacted swiftly, implementing comprehensive security measures. It was therefore not unusual when, on Sunday 7 September 1970, the security officer responsible for El Al Flight 219 departing from Amsterdam to New York singled out four suspicious passengers for additional security controls: a couple on their honeymoon and two men traveling on Senegalese diplomatic passports. The honeymooners, after a pat down, were allowed to board the El Al flight. Unbeknownst to the security officer, the woman was twenty-four-year-old Leila Khaled, a poster girl for the PFLP who was well known to Israeli officials for the highly publicised hijacking of a TWA aircraft one year earlier. Her partner was Patrick Argüello, a US citizen known to the FBI for his activities in South America.
The two other men had both purchased their tickets that same morning and had paid in cash. Their passports also had sequential numbers, providing enough indicators for the officer to deny them boarding the El Al flight; they were rebooked on a Pan Am flight to New York. Unfazed by the setback, the two decided to hijack the Pan Am 747 instead. While Khaled and her companion boarded the El Al flight in Amsterdam as planned, two other groups of terrorists boarded Swissair Flight 100 in Zurich and TWA Flight 741 in Frankfurt. The hijackers were well prepared. Armed with hand grenades and guns, they also carried with them flight path information, up-to-date Jeppesen air navigation maps including information concerning fuel calculations. When, during the hijacking of the TWA aircraft, Captain Carroll Woods attempted tricking them into believing there was not enough fuel for the trip, the hijackers assured him that they could see that there was!
Twenty minutes after take-off, Swissair Flight 100 was well on its way when Captain Fritz Schreiber heard a noise in the first-class galley. Seconds later, a man stood in the cockpit door holding a gun to a flight attendant’s head, yelling nervously in broken English. The situation was so strange, Captain Schreiber had to laugh aloud. Only when he saw the hand grenade with the safety pin removed did he realise the precariousness of the situation. Almost simultaneously, the same attack sequence played out on the TWA, El Al and Pan Am flights.
The terrorists executed the takeover of the four planes with speed and surprise. Using flight attendants as hostages, they gained access to the cockpits. The sole exception was El Al Flight 219. There, one crewmember pushed a recently installed hijacking alert switch, warning the cockpit of the impending takeover. When the two terrorists stormed their way towards the front, the captain put the Boeing 707 in a steep downward spiral, which sent the attackers tumbling through the cabin. Knocked off their feet, Leila Khaled was overwhelmed by passengers and an armed guard shot Patrick Argüello who later succumbed to his injuries.
By early Sunday afternoon, the PFLP had almost five hundred passengers and crewmembers under its control. While the El Al Boeing made an emergency landing at Heathrow, the three other flights continued their journey towards an abandoned British airfield, named Dawson’s Field, in the Jordanian desert near the town of Zarqa. The pilots had to make the landing in almost complete darkness with the runway illuminated by torches and car lights. Using thrust reverse on all four engines, the Swissair DC-8 came to a standstill only seventy-five feet behind the TWA Boeing 707, narrowly avoiding a catastrophic collision in the dark night. The Pan Am 747 was unable to land in Zarqa due to its size and so diverted to Cairo, where the two terrorists blew the brand new plane to pieces only minutes after the last hostage had disembarked.
Three days later, the PFLP hijacked another plane, a BOAC Super VC-10 en route from Mumbai to London via Bahrain, to land on Zarqa’s desert airstrip. Negotiations concerning the hostages held by the PFLP involved Germany, Israel, Switzerland, the UK, as well as the United States. On 12 September 1970, the PFLP summoned a western cameraman and a photographer to the desert airfield and, in a spectacular explosion, destroyed all three planes, creating an iconic image of the burning airliners. A few weeks later, all hostages were finally freed and brought home safely. Both sides claimed victory. Western governments had successfully brought home all their hostages alive, while the PFLP had confronted both Israel and the United States and obtained the release of seven imprisoned terrorists in Germany, Switzerland and the United Kingdom. However, it proved to be a shallow victory for both parties. The animosity towards the PFLP grew with each subsequent terrorist attack while the West faced a continuous threat of terrorist attacks for decades to come.
“…the Swissair DC-8 came to a standstill only seventy-five feet behind the TWA Boeing 707, narrowly avoiding a catastrophic collision…”
Looking back at the events of 1970, the question remains why airports and airlines were so badly prepared for these attacks. As aforementioned, skyjackings were a common occurrence in the US and terrorist attacks were a serious threat in Europe from 1968 onward. An earlier PFLP attack on El Al Flight 432 in Zurich in February 1969 demonstrated just how simple it was to smuggle weapons on a plane. The attackers prepared their operation in Vienna but chose to fly by plane to their target in Switzerland, a destination commonly reached by rail. Their choice was based on the fact that the chance of being caught with AK-47 rifles, hand grenades and explosives was much higher when passing border controls at train stations than through any security measure at airports. The deadly ground attack in Zurich proved to be a wake-up call for the Swiss national aviation authority. Reports, instructions, as well as protocols stored in the state archive of Zurich, illustrate a steep learning curve following the attack. Security controls were tightened on certain flights and instructions for the screening of passengers and guarding of planes on the tarmac were issued. However, looking through these new guidelines, it becomes clear that terrorist activities from Palestinian groups were, at least on an operational level, primarily perceived as a threat aimed at Israel and not so much against civil aviation in general.
But pinpointing the lack of security measures to the narrow focus on flights to Israel falls short. There was not a single cause but several elements ensuring the unpreparedness of European airports against the simultaneous attacks in September 1970. First, air carriers displayed a strong resistance towards extended and upgraded security controls. Second, a general perception prevailed that the threat was specifically against flights to and from Israel and third, there was a severe shortage of manpower at airports during the build-up phase of the new security controls. The aversion by the airline industry towards security controls was not only visible in the US during the skyjacking epidemic in the mid- to late-1960s, but also in Europe.
One year before ‘Skyjack Sunday’ the Swiss airport police tightened its security for Swissair and BOAC flights to Israel, demanding the strict examination of IDs, visas and travel documents. “Primarily Arab looking passengers are suspicious,” declared an internal document advising thorough security checks on such passengers. But in the same document, the orders were extenuated with the remark that, “If the security check proceeds without results, we apologise politely for the inconvenience.” Only days after issuing these new guidelines, the Swiss Aviation Authority had to confirm that these measures were legal and should be upheld. This can be seen as a potential indicator of strong pressure to dispose of the measures as soon as possible. Furthermore, internal memorandums show how airport police in the early 1970s franticly struggled to adopt to new security restrictions, hiring daughters and spouses of airport police officers as part-time security officers.
“…the chance of being caught with AK-47 rifles, hand grenades and explosives was much higher when passing border controls at train stations than through any security measure at airports…”
While the attacks of September 1970 were a shock to the world, the question remains whether the aviation security community learned its lessons from these events. While it took 30 years for another simultaneous terrorist attack to materialise, it seems that law enforcement, airport security, as well as air carriers, stepped into similar traps and mistakes in 2001. The parallels between ‘Skyjack Sunday’ and ‘9/11’ are striking. Both operations relied on simultaneous attacks against four different planes, using hijacking as the modus operandi. In both cases, the attackers’ choice of weapons reflected the weakness of the implemented security controls at the time. In 1970, when security controls were sketchy or even non-existent, hand grenades and guns were chosen, while in 2001 the weapons of choice were boxcutters which were not even listed as prohibited items.
“…just as in 1970, when the focus of security controls was on flights to and from Israel, so enhanced security controls in the 1990s exclusively focused on international flights…”
During both attacks, small teams exploited the airlines’ standard operating procedures. The PFLP integrated into their modus operandi the fact that an airline pilot was supposed to open the cockpit door if the life of one of his crewmembers was threatened. On El Al flight 219 the hijackers were puzzled when the captain refused to open the door, even though one of his flight attendants was in mortal danger. With the three other flights, the gamble paid off. Thirty years later, the successful 9/11 attacks relied on a behaviour the al-Qaeda agents had noticed during several trial runs in the summer of 2001. Cockpit crews on domestic flights, no matter which airline, opened their doors fifteen minutes after take-off, a habit that provided the terrorists with a point of attack.
“…as airlines and airports are more concerned with customer satisfaction than security, authorities struggle to enforce new measures while terrorist organisations themselves capitalise on loopholes identified during trial runs…”
While the airline industry fought proposed security controls throughout the 1960s, the ‘9/11 Commission’ concluded that the air carriers’ approach towards security regulations had not changed at all. Still the industry faced new security measures with a tactic of “decry, deny and delay”. Very few security measures proposed by the Gore Commission in 1997 had been implemented, once again due to strong resistance from the industry. Additionally, the threat landscape in the early 2000s focused on international flights. Domestic flights were not considered to be a target and, therefore, were subject to a minimal amount of oversight. Just as in 1970, when the focus of security controls was on flights to and from Israel, enhanced security controls in the 1990s exclusively focused on international flights.
Looking at the terrorist attacks of 1970 and 2001 from a historical perspective, two things become apparent. First, archival documents indicate a steep learning curve after each terrorist attack. New measures such as the profiling of passengers or the guarding of airliners on the tarmac were adopted. However, as subsequent terrorist attacks show, the implemented security controls were never as effective as intended. While in both cases new security measures were put in place prior to the attacks, the implementation was fragmentary and did not mirror the initial learning curve. For instance, while passengers were questioned in the early 1970s before they boarded their flights to and from Israel, PFLP terrorists still made it onto each targeted flight. Moreover, in 2001, although it was clear that the terrorist threat was increasing, the selectee system, which ensured that suspicious passengers were identified, only covered the thorough search of hold baggage, ignoring the hand luggage of the selectee. Some critics identify the well-known reactiveness of aviation security measures as the main reason for its continuous shortcomings, arguing that security measures are only implemented after a terrorist attack and therefore are always inevitably too late.
However, looking at terrorist attacks from a historical vantage point shows that the problems are much more complex. As ‘Skyjack Sunday’ shows, security measures were already in place. The challenge of countering terrorist attacks is not overcome simply by implementing security measures. While in most cases the learning curve after terrorist attacks is clearly visible, a variety of different factors influence and deter security measures from being fully embraced. As airlines and airports are more concerned with customer satisfaction than security, authorities struggle to enforce new measures while terrorist organisations themselves capitalise on loopholes identified during trial runs. This interdependency of a multitude of factors needs to be taken into consideration in order to confront new terrorist threats in the future; only then will we be able to learn from our past mistakes.
Dr. Jonathan Zimmerli has an MA in Intelligence Studies from Brunel University London and holds a PhD in History from the University of Bern. He works at the Swiss Federal Office of Civil Aviation as an aviation security inspector. Additionally, he is currently engaged in academic research focusing on FAA’s intelligence and threat picture prior to the 9/11 attacks.
Aviva Guttmann, The Origins of International Counterterrorism, Switzerland at the Forefront of Crisis Negotiations, Multilateral Diplomacy, and Intelligence Cooperation, (1969-1977), Leiden, 2018
Brendan I Koerner, The Skies Belong to us, Love and Terror in the Golden Age of Hijacking, New York, 2013
David Raab, Terror in Black September, The First Eyewitness Account of the Infamous 1970 Hijackings, New York, 2007
The 9/11 Commission Report, Final Report of the National Commission on Terrorist Attacks Upon the United States, 2010
Gaetano Joe Ilardi, The 9/11 Attacks – A Study of Al Qaeda’s Use of Intelligence and Counterintelligence, in: Studies in Conflict&Terrorism, 32:3, 2009