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Airport & Aviation Security

07/09/2012 | by Sinai, Joshua  

First published in the The Journal of Counterterrorism & Homeland Security International (Fall 2012)

Since the advent of modern terrorism, the transportation sector has been among the most frequent targets of terrorist attacks. For those determined to kill indiscriminately and in massive quantities to inflict mass casualties, economic disruption, world headlines, and psychological anxiety and fear among wider publics, aviation transportation in the form of airplanes and airports are ideal targets. Also making them ideal as potential targets is that they cannot easily be protected without interrupting the flow of passengers and goods which the general public takes for granted.

The aviation sector is especially vulnerable because large numbers of people pass through airports on a daily basis. During holiday seasons, the volume of passengers increases exponentially, resulting in the issuance of heightened threat levels. On a tactical level, aviation transportation provides alluring targets for terrorism because of the high volumes of people located in a particular location at airports, such as ticket counters, the high concentration of people on large airliners and the potential for high death rates caused by blowing up such aircraft, and the utility of using a hijacked airplane as a lethal weapon to inflict additional catastrophic damages by flying them into physical structures on the ground.

As terrorists continuously attempt to exploit new vulnerabilities in aviation transportation, in one of the latest targeting trends on July 17, 2012 a suicide attacker bombed a bus with a group of newly arriving Israeli passengers on board, as it was still parked in the terminal of Sarafovo Airport, in Burgas, Bulgaria.

Also of concern is the security of aviation cargo. While a high percentage of air freight is carried in passenger planes, which are subject to inspection by x-ray, the rest is transported on specialist cargo planes, with only a small amount of air cargo checked in the same way.

Terrorist Threats Against Aviation 

The greatest catastrophic attack against the aviation sector was al Qaida's coordinated, simultaneous hijacking of four airliners on September 11, 2001, intentionally crashing two of the planes into the World Trade Towers in New York City, with the third plane crashing into the Pentagon, in Arlington, VA. The fourth plane crashed into a field near Shanksville, PA, after passengers attempted to take control before it could reach the hijackers' intended target of Congress or the White House in Washington, D.C. Nearly 3,000 people died in those attacks, including the hijackers and passengers on board the planes. Those coordinated attacks demonstrated glaring vulnerabilities in U.S. aviation security at the time, which the U.S. government and its allies around the world have since attempted to substantially upgrade.

In response, a spectrum of security techniques and methods have been implemented to protect the aviation sector from future terrorist attacks. It is part of a sort of endless "cat and mouse" game being played by government agencies to continuously innovate technologies and methods to upgrade their aviation security while terrorist groups, such as al Qaida and its affiliates, seek to identify new vulnerability gaps to exploit as they have been doing since 9/11, and use new techniques to target this sector to inflict maximum casualties and physical, economic and psychological damages against their nation-state adversaries.

Terrorist Incidents

The aviation sector has long been targeted by terrorist groups. In the 1970s and 1980s hijacking airlines was a widespread terrorist tactic, with the hijackers using the airliners as a negotiating tactic, either to free prisoners, concede to political demands, or extort ransom payments. One of the first hijackings by a Middle Eastern terrorist group, which was also the first time an Israeli airliner was hijacked, occurred on July 22, 1968, when an El Al plane departing from Rome and headed for Tel Aviv, Israel, was hijacked by the Popular Front for the Liberation of Palestine (PFLP), and diverted to Algiers. Its crew and passengers were held hostage for five weeks and were released following 40 days of negotiations. Following the hijacking, El Al became extremely security-conscious and instituted the first baggage check program.

This was followed on September 6, 1970 when PFLP operatives hijacked four airliners departing from European airports, diverting two to a disused airfield in the Jordanian desert, with a third airliner diverted to Beirut and then Cairo. Another hijacking attempt was thwarted by El Al security its flight from Amsterdam. On September 9, a PFLP sympathizer seized a BOAC flight in Bahrain and brought it to the same Jordanian airstrip as the first two.

On May 30, 1972, after departing their aircraft, three members of the Japanese Red Army carried out an attack at Lod Airport (now known as Ben Gurion International Airport), in Tel Aviv, killing 24 people and injuring 78 others.

On 27 June 1976, Air France Flight 139, originating in Tel Aviv, took off from Athens, Greece, heading for Paris, was hijacked by two operatives belonging to a PFLP offshoot, who were joined by two German terrorists. The airplane eventually arrived at Entebbe Airport in Uganda.

Finding it difficult to hijack aircraft due to intensified security measures, so in December 1985, Palestinian Abu Nidal Organization (ANO) operatives attacked the Israeli national El Al airline's ticket counters at the Rome and Vienna airports, killing 20 people. A similar incident occurred on July 5, 2002, when an Egyptian-American gunman opened fire at El Al's ticket counter at Los Angeles International Airport, killing two people and injuring four.

Prior to 9/11, the deadliest airline catastrophe occurred on June 22, 1985 when Air India Flight 182, operating on the Montréal–London–Delhi route, was downed by a bomb on board that had been placed by Sikh terrorists, killing its 329 crew and passengers.

In an example of state-directed terrorism, in November 1987, two North Korean operatives planted a bomb on a Korean Airline Boeing 707 en route from Baghdad to Seoul, causing it to explode in midair over the Andaman Sea off the coast of Burma, killing its 20 crew members and 95 passengers aboard.

In another major airline bombing, on December 21, 1988, Pan Am Flight 103, a Boeing 747, en route from London Heathrow to New York's JFK International Airport, was destroyed by a bomb on board as it was flying over Scotland, killing its 243 passengers and 16 crew members. The aircraft's explosion also resulted in the deaths of 11 people in Lockerbie, in southern Scotland, as large sections of the plane fell, destroying several houses. The Libyan government was charged for the bombing.

In examples of terrorist groups such as al Qaida and its affiliates continuously attempting to exploit gaps in aviation security they were largely thwarted in their attempts, despite the innovative tactics and weaponry used in each operation. The most notable forerunner of catastrophic airliner bombings was the December 11, 1994 bombing of Philippine Airlines Flight 434. Although the explosion was small, killing one person, with the plane making an emergency landing, it turned out to be a test run for a planned terrorist attack by Ramzi Yousef, called Operation Bojinka, to blow up 12 airliners and their approximately 4,000 passengers as they flew from Asia to the United States. Yousef's uncle, Khaled Sheikh Mohammad, later used this blueprint of using multiple airliners in a single operation to plan 9/11, with the terrorists' goal not merely to hijack aircraft but to use them as suicide bombs to cause mass destruction.

The Bojinka plot was later duplicated by an al Qaida conspiracy in August 2006, which was foiled by British authorities by arresting the operatives during the pre-incident phase, to bypass bomb detectors at airports by detonating liquid explosive bombs on board multiple airliners destined for Canada and the United States. The plot led to tighter restrictions on carrying liquids and gels in hand luggage in the European Union, Canada, and the United States.

Another innovative al Qaida operation was the attempt by Richard Reid, a British national, to detonate his special shoes packed with plastic explosives in their hollowed-out bottoms on board American Airlines Flight 63 from Paris to Miami on December 22, 2001. In a similarly innovative plot, on December 25, 2009, Umar Farouk Abdulmutallab, a radicalized Nigerian who had been studying in London, attempted to detonate plastic explosives hidden in his underwear while on board Northwest Airlines Flight 253, en route from Amsterdam to Detroit, Michigan.

Further innovating their tactics against aviation, on November 28, 2002, shortly after Arkia Israel Airlines Flight 582, in a Boeing 757-300 aircraft, took off from Moi International Airport, in Mombassa, Kenya, al Qaida operatives fired two SA-7 surface-to-air missiles, which narrowly missed the plane, which was en route to Israel, although they caused two trails behind the left wings, causing the aircraft to rock slightly.

In a different type of innovative tactic against the aviation sector, in late October 2010, al Qaida in the Arabian Peninsula (AQAP) placed several sophisticated parcel-bombs containing 300-400 grams of the explosive PETN on passenger and cargo planes. Although the bombs did not go off, they severely disrupted freight and parcel traffic in the region.

Even when faced with increased security, terrorists are not abandoning airports as venues for their attacks, as demonstrated on January 24, 2011 by a suicide bombing attack by North Caucasus Islamist militant in Moscow's Domodedovo Airport's international arrivals hall, killing 35 and wounding 152. And, as mentioned earlier, on July 17, 2012 a suicide attacker bombed a bus with a group of newly arriving Israeli passengers on board, as it was still parked in the terminal of Sarafovo Airport, in Burgas, Bulgaria. Seven people were killed (including the attacker) with some 30 others injured.

Airports and Airlines Most Vulnerable Worldwide

Since the terrorist attacks of September 11, 2001, with concerns raised about the effectiveness of security, as the 19 hijackers managed to pass through checkpoints to board the aircraft with their box knives and, with few exceptions, without being placed on 'No Fly' lists, as which was followed by the gaps in security that enabled Abdulmutallab to board the flight to Detroit in December 2009, security at many airports worldwide has been substantially upgraded to lower the probability of comparable attacks occurring again.
Certain airports around the world are of concern because of lax security or being located in volatile regions plagued by widespread terrorism-related extremism. Under this categorization, airports of the first tier of concern would include those in countries considered as "state sponsors of terrorism," such as Cuba, Iran, North Korean, [North] Sudan and Syria. Second tier airports of concern are those in regions of weak or failed states and terrorist "hotspots," such as Lebanon, Libya, Pakistan, Somalia, and Yemen. Third tier airports of concern are located in countries undergoing turbulence, such as Egypt, Nigeria, Tunisia, and others, which might affect the degree of security at their airports.

All passengers flying, for example, to the United States from such countries face increased random screening, with some patted down and subjected to careful searching of their carry-on bags. In practice, this would result for a traveler with a Yemeni passport or a passenger transiting through Yemen to be subjected to an extra body inspection or scan when transferring from a European airport to the U.S.

Based on terrorists' targeting history, Israeli airliners would be considered their top targets, with U.S. airliners in second place. In a further breakdown of terrorists' targeting, the downing of large aircraft would be favored over smaller planes.

Measures to Secure Airlines and Airports

Effective security is intended to make attacks more difficult for terrorists, increase their likelihood of being detected, minimize casualties and disruption, reduce resulting panic and anxiety, and reassure passengers that the aviation sector is safe and secure. It is also recognized, however, that no single defensive measure or technology is sufficient in being 100 percent effective in thwarting inventive and determined terrorist operatives. To be effective, a security regime must be multi-layered, employing measures and technologies to secure airports and aircraft, beginning at the operational level with what are called "watchlisting" databases containing information about individuals that might have a nexus to terrorism to prevent them from flying, to the tactical level where armed guards are deployed to maintain security at airport terminals and screeners who manage body scanners and explosive trace detection systems, as well as profile passenger behaviors to detect possible suspicious intent. Finally, since no security system can ever be 100 percent airtight, a widely accepted security notion is for airport security managers to adopt risk management principles in the allocation of resources that invest in robust watchlisting operation centers, allow for greater flexibility by security officers at airports’ checkpoint screening posts, deploy randomized security procedures to keep potential terrorists off-guard, continuously reassess the evolving terrorist threat, and conduct appropriate behavioral profiling of potentially suspicious passengers.

Watchlisting Databases

One of the best lines of defenses in aviation security is the "No-Fly" list. Virtually all governments around the world maintain such databases with information about individuals deemed suspicious. As this system, as soon as people purchase an airline ticket, their airlines are required to submit lists of their passengers, including their names and dates of birth, to the their appropriate government transportation security administrations, which then compare the names to their own watchlist databases to determine their suitability to fly. In the U.S., the FBI's Terrorist Screening Center (TSC) maintains the database of individuals from around the world who are not permitted to board a commercial aircraft for travel in or out of the United States. As of summer 2010, according to the TSC the list contained about 8,500 names. Additional lists tag would-be passengers for extra inspection. These lists differ from the Terrorist Watch List, which is larger list of individuals suspected of some involvement with terrorism. As of summer 2011, the Terrorist Watch List contained around 400,000 names, according to the TSC. Various means are available to individuals whose names might have been inadvertently added to such lists to enable them to appeal to be removed from them.

In a new trend related to watchlisting, airports have introduced a program for frequent flyer passengers to pay a charge to undergo a background check to enable them to by-pass the ordinary security lines by using a special fast track security facility.

Security on Aircraft

One of the first requirements of aviation security is installing bulletproof and locked and strengthened cockpit doors to protect the aircraft's pilots from unauthorized access. An additional measure is equip some aircraft with CCTV cameras, to enable pilots to monitor potentially suspicious activities inside the cabin. Pilots are given the option of carrying a gun, once they are trained to use it. Finally, federal air marshals are deployed in many flights to ensure an added layer of security. As they blend in with other passengers on board the aircraft, to protect the flying public they employ their investigative techniques, criminal terrorist behavior recognition, aircraft specific firearms techniques and close quarters self-defense measures.

Airport Screening

In the first line of defense are airport security guards who patrol, observe, report on any suspicious activities they might encounter, or protect by deterring any violent activity on the premise they are working. Security guards can be armed or unarmed, requiring either a patrol or static position.

In the second line of defense, screeners are deployed to check the millions of passengers who fly around the world daily. They are the human component of the technological system of metal detectors, X-ray machines, and explosive sniffers. At many airports, the screeners are complemented by contingents of armed guards who patrol the facilities. In the U.S. prior to 9/11 airport screening was provided by private security companies which were contracted with an airline or airport, but this changed in November 2001 with the Transportation Security Administration (TSA) deploying its own personnel to handle screening at all US airports.

In a tightening of checkpoint screening, those passengers who set off a walk-through metal detection alarm, however innocently, are then patted-down and thoroughly checked with a hand-held metal detector. Those detectors can scan and detect within seconds the spectrum of chemical, biological, radiation, nuclear and explosive materials.

In response to the August 2006 London plot, a new screening measure was instituted to forbid passengers from carrying liquids, gels and aerosols in quantities greater than 3 ounces, with all permitted bottles placed in a clear plastic bag and sent through screening separately.

Finally, all passengers must show valid government-issued identification documents in order to fly. These are checked to ensure that they match the passenger's information on the printed boarding pass.

Behavioral Profiling

Behavioral profiling is considered an effective component in aviation security, if done correctly, especially when it is not based on racial, religious, or ethnic grounds. The earlier and more precisely that a potential threat can be identified prior to a passenger with suspicious intent boarding an aircraft, the sooner that preemptive measures can be taken, beginning with secondary screening. Behavioral profiling not only checks for persons who might be behaving suspiciously, but those with an unusual travel patterns, such as travel to countries of concern.

With terrorist groups continuously seeking to recruit new operatives who do not "fit" stereotypes associated with their membership, the use of behaviorally-based profiling can, therefore, be efficient and judicious.

A "best practice" in behavioral profiling is the "Behavior Pattern Recognition" (BPR), a tool and training program developed by Rafi Ron, a former director of security at Israel's Ben Gurion Airport and a veteran aviation security expert. It provides airport security staff with the capability to recognize and assess passengers' behaviors ranging from distress or confusion to potential criminal or terrorist intent that may not correspond with what could normally be expected in a particular environment. The BPR, which has been deployed at many airports around the world, was developed to provide security personnel a risk-based decision making process to meet the level of threat facing them, without engaging in religious discrimination or racial profiling .

Ramifications of Upgraded Aviation Security

While continuously improving aviation security, the vast upgrades in such methods and technologies have also incurred a spectrum of economic costs, whether direct in terms of increased costs for government, local authorities and airlines to implement them or in increased inconveniences to passengers who have to arrive at airports several hours prior to their scheduled departures and wait on lengthy and time consuming security lines.

The restrictions accompanying upgraded security have also led to debates over issues such as the need for security versus civil liberties for passengers. Such debates over privacy violations are expected to grow, especially over the expansion of watch lists and as airport security increases the use of invasive whole body imaging (WBI) and biometric screening devices and behavioral recognition technologies to detect potential suspiciously hostile behavioral intent. To overcome such controversies, new screening technologies are being developed, such as what is known as a “millimeter wave technology,” which is still in the experimental stage, and is expected to be less intrusive with the images analyzed by computer, not a human operator.

Additional concerns over upgraded security technologies are medically related, as they might affect people with medical conditions, the elderly and pregnant women who might be negatively impacted by such radiation technologies.

New Trends

With the "cat-and-mouse" chasing games between government agencies and terrorists continuing to escalate, certain potential new trends are discernible. With hardened security at airport terminals and aircraft, terrorists might resort to new warfare tactics such as bombing them in mid-air by firing heat seeking shoulder-launched surface-to-air missiles, such as manpads. Another new trend might not involve attacking civilian aircraft, but using remote-controlled “small drone airplanes” packed with explosives and guided by GPS to attack their intended targets. In an example of the latter tactic, in late September 2011, Rezwan Ferdaus, of Massachussetts, was arrested for plotting to use a remote-controlled F-86 Sabre in his plot to attack the U.S. Capitol and the Pentagon. In another possible new trend, just as the Iranians had succeeded in downing a flying U.S. “stealth’ drone over its territory in December 2011, it may be possible (although with great difficulty if they are properly encrypted) for terrorists to "hack" into an aircraft’s GPS system and “spoof” its GPS receiver with false navigational information. Another trend of concern to civilian aviation is the possibility of passengers who are infected with deadly biological diseases to become agents of global epidemics once they arrive at their various destinations. Finally, with the inside perimeters of airport facilities being increasingly hardened, terrorists are now targeting the newly arriving passengers as they board their buses outside the terminals, as demonstrated by the July 17, 2012 attack at Sarafovo Airport in Burgas, Bulgaria.

In response, government agencies are also coming up with a spectrum of new countermeasures. For example, to circumvent an aircraft's engines from being attacked by a heat seeking surface-to-air missile, a decoy flare has been developed as a countermeasure. As proposed in a report by a homeland security association, another new countermeasure would involve the application of artificial intelligence ranging from deploying sophisticated imaging technologies using advanced algorithms that make sensors and cameras ‘smart’ to predictive analytical software that identify suspicious human behavioral patterns, including terrorists' pre-incident 'dry runs.' In the future, the report adds, machine learning, computer vision and artificial intelligence could be combined in new ways to push out security checkpoints from the terminal to the street curb.


The views expressed in this publication are solely those of the author(s) and do not necessarily reflect the views of the International Institute for Counter-Terrorism (ICT).