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A
irport perimeters are typically
protected by fences designed to
delineate land ownership and
dissuade pedestrian access. Chain-link
fences of various types are most
commonly used for long-perimeters
due to their low unit cost, but chain-
link fences present a delay to pedestrian
attack that is measured in seconds, and
no delay to a vehicle attack. This is why
in October 2003 a Ford Mustang was
able to drive through a double
perimeter fence at San Diego
International Airport in California and
cross an active runway.
Vehicles have been used as weapon
systems for decades. One of the earliest
examples was on 16 September 1920,
when the Italian anarchist Mario Buda
drove a horse-drawn cart-bomb to the
corner of Wall Street and Broad Street
in New York and detonated it outside
the offices of J P Morgan, killing 40
people. Today in Iraq and elsewhere in
the world, suicide car bombs will be
used, as they have been almost daily
since the euphoria of Iraq’s liberation
subsided. Together with Mikhail
Kalashnikov’s rifle, the suicide car
bomb now appears to be the weapon of
choice for the anti-democracy terrorist.
Thankfully, since 11 September 2001,
the risk of an aircraft being attacked by
passengers from within the cabin has
been significantly reduced, as too has
the risk of an attack on passengers
within an airport terminal building.
Although the terminal building at
Glasgow Airport was attacked by a
vehicle in June 2007, its mitigation
system was successful at defeating the
vehicle and the only casualty was the
terrorist himself. But little has been
done to mitigate the risk posed by
vehicles attacking an aircraft while on
the ground or during those precarious
moments during the take-off sequence.
The reason for a lack of aircraft
protection may not be the technical
difficulty. Protecting the airport is the
responsibility of the airport owner. Yet
protecting an aircraft and its passengers
is primarily the responsibility of the
aircraft operator. Internationally, Annex
17 of the Convention on International
Civil Aviation gives guidance on
safeguarding civil aviation against acts
In light of the 2007 attack on Glasgow airport, Matthew Walton-Knight
suggests that the next generation of terrorist attacks on
aircraft will be from ground vehicles
UNDER
SIEGE

2. of unlawful interference. It requires
governments to establish security
programmes with their airport owners.
In Europe, the European Civil Aviation
Conference Document 30 Part Two
guides the implementation of Europe-
wide aviation security measures. In
Britain, under both Common Law and
Section Four of the Health and Safety at
Work Act, airport owners have an
obligation to provide – as far as
reasonably practicable – safe premises
for aircraft operations. But the cost of
airport security in Britain is causing
airport owners concern as, unlike road
and rail security, airport security costs
fall completely to airport owners.
Terrorists have and will attack airports
for they are high-value, target-rich
environments – in March 1994 the
Provisional Irish Republican Army (IRA)
attacked London’s Heathrow Airport.
Pragmatically, there are four attack
scenarios in which a vehicle with – or
even without – an explosive device
could easily attack an aircraft on the
ground at an airport. In the first
scenario, a vehicle bomb detonates in
the vicinity of a moving or stationary
aircraft. A line of stationary, fuelled and
fully-laden passenger aircraft queuing to
take-off presents a most attractive target
to a terrorist intent on generating mass
casualties. Thankfully this attack
scenario has not yet been realised, but
the effect of a close proximity
detonation of even a small vehicle bomb
on an aircraft would be catastrophic.
In the second scenario, a vehicle
could strike an aircraft where the
particularly vulnerable components are:
the undercarriage to trip-up the aircraft,
or the engines to initiate a fire. In
October 2000, a Singapore Airlines
Boeing 747 was taking off from Taipei
Airport in Taiwan and struck stationary
construction equipment and vehicles,
killing 83 people on-board. An aircraft
could also potentially swerve off the
runway to avoid an attack vehicle. In
July 2006, a Russian S7 Airbus A-310
skidded off the runway at Irkutsk Airport
in Siberia and struck a building, killing
124 people on-board.
Another hypothetical scenario could
see an aircraft attempting to avoid a
vehicle strike but hit debris – deliberately
placed or not – from an attack vehicle.
In July 2000, an Air France Concorde
taking off from Paris Charles de Gaulle
Airport struck a small item of debris on
the runway that was thrown-up,
punctured a fuel tank and caused a fire.
The aircraft crashed minutes later,
killing all 109 people on aboard.
Accepting that aircraft are highly
vulnerable to terrorist attack when on
the ground, there is much that can be
done to mitigate this risk. But in order
to progress, two principles must be
acknowledged. Firstly, once an attack
vehicle is within the secure airside
perimeter of an airport, little can be
done to restrain it. Airports are designed
to give near complete freedom of
movement for vehicles airside in order
to allow aircraft movement and
emergency response. Short of a
significant armed engagement, effectively
nothing can stop an attack vehicle once
it is airside. The vehicle must be stopped
prior to penetrating the airside perimeter.
Secondly, the focus of any perimeter
security system must be on the terrorist
attacker, not on the security system.
Many manufacturers promote
impressive perimeter security systems,
but this can easily move the focus away
from the terrorist attacker to the
security system. Sun Tzu reminds us
that, “If you know yourself and your
enemy, then you need not fear the
result of a hundred battles; if you know
yourself but not the enemy, for every
victory you will suffer a defeat.” In
counter-terrorism, one defeat is one too
many; the focus must remain on the
terrorist attacker, not on the security
system, to ensure “no defeats”. By
focusing on the perimeter security
system and not on the attacker, defences
can easily become out of balance, in
that they give differing levels of residual
risk along the perimeter – the proverbial
robust front gate but undefended
tradesman’s entrance. This either
provides a weakness that can be
exploited by terrorists, or leads to
uneconomic defences through the
overprovision of protection in some areas.
An ideal perimeter protective system
should deliver similar levels of residual
risk throughout its entire length.
Halting an attack vehicle at the
perimeter is difficult. Vehicles are able to
breach many obstacles, especially when
they are driven by determined terrorists
with no intention of escape or indeed of
their own survival. This means that the
spectrum of risk mitigation solutions is
limited, but still includes some fences,
blocks, bollards, walls and ditches. But
the perimeter engineering solution is
only an element, one layer in the
perimeter defences of an airport – all
obstacles can be breached, given
adequate time and resources. Securing a
perimeter is not just a process of placing
fences and barriers, nor of adding
intruder detection systems and cameras
to an existing perimeter fence. It
involves the application of a
methodology that allows the security
team to understand – and ideally to
adopt – the mindset of the terrorist
attacker. Few outside the army or
security services are educated to
conceptualise in this manner and
consequently there is value in using a
military-style methodology for long-
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3. PEER REVIEW
Eric Yap
A qualification should be made on the
airport perimeter security issue. While
it is true that airport perimeters are
generally protected by chain-link
fences that are often complemented by
several other layers of security (both
passive and active systems) that need
not necessarily be conspicuous. This is
particularly true for major aviation
centers which would naturally be high
on value to terror groups. Examples of
such airports in Asia would be Hong
Kong International Airport, Kuala
Lumpur International Airport and
Singapore’s Changi Airport.
My take is that terror groups have
easier options to explore within an
airport context than to penetrate
through highly visible defences.
Passenger terminals offer an extremely
attractive target and like subways, it is
almost impossible to check very
person without bringing the system to
a standstill.
perimeter security.
Airports are inviting high-value
target-rich environments. If attacked
they would give terrorists extensive
media coverage, considerable political
leverage and, depending on the strategy,
potentially massive loss of life. There
would also be significant financial and
business continuity implications.
Unquestionably, an attack on an airport
would achieve the purpose of terrorism
– to terrorise. Mitigation of the risk
posed by a vehicle attack on an aircraft
while on the ground at an airport
should be a priority. It is the logical next
form of terrorist attack our air
transportation networks will face.
Although the primary onus lies with
aircraft operators, airport owners have
an obligation to ensure their airports
are safe and secure. Effective mitigation
strategies will focus on defeating the
terrorist attacker at or before he
penetrates the airside perimeter, rather
than on constructing potentially
nugatory perimeter security systems.
Attack vehicles must be prevented from
penetrating the perimeter, for once
inside their effect would be catastrophic. A
vehicle attack would be highly effective
for a terrorist and, with the perimeter
defences currently found on most
airports, it is easy to achieve.
Regrettably, unless aircraft operators
and airport owners are more proactive
at risk mitigation, a vehicle attack on an
aircraft at an airport is now just a
matter of time.
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UNDER SIEGE
The 2007 Glasgow Airport attack was thwarted by effective perimeter security but the threat remains
©GettyImages
Matthew Walton-Knight CEng PMP
works for MMM Group in
Vancouver, Canada. He previously
served in the British Army’s Corps
of Royal Engineers and worked for
Arup Security Consulting.
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