Home' RTCA Documents for Review : DO-230H FRAC Contents 102
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The PACS has distinctive power requirements at each level of the system, and distinct components may
require a separate approach to ensure system-wide operation in case of a power interruption. Some PACS
controllers have their own UPS while others may require connection to an external UPS. When one element
of PACS does not operate properly, security of the airport is at risk.
Servers are of course the key component and usually get the most attention to power requirements. A server
has to have a minimum level of watts to work as expected. An airport should have a study made of the total
power being supplied to the server(s) compared to the supply requirements. Just because a server starts up
does not mean it will operate efficiently if the power is sub-standard. As stated previously the server should
always be configured with redundant power supplies. Periodical testing of the power supplies will ensure
they are functioning.
Network appliances are not usually thought of as part of a PACS, but without them, there is no PACS.
There has to be coordination between the installers of PACS and network technicians for data continuity.
Field controllers will need power, but in general do not draw much. Most controllers are manufactured with
a built-in battery for power outage, but if they do not, some type of UPS will be needed. Portal locking
hardware is triggered and monitored by the field controller. The physical open/close function of the
hardware does require low voltage. Without power, the actuator is not going to function.
Locking hardware are available in two main categories: Fail-Safe and Fail-Secure. A Fail Safe device is
powered to lock and unlocks when power is removed. A common example is a magnetic lock.
A ‘fail secure’ device is unlocked when power is applied. For this reason, UPS calculations take into
consideration the type of locking device, specified current requirement of each lock, the number of openings
per hour and the number of hours the UPS is expected to keep the system operational.
Emergency power can be very costly depending on what part of PACS it is supporting. The most frequently
used option is a universal power supply (UPS) and also often very not adequately sized for the job. Each
UPS manufacturer can provide the formula for what size is needed; the calculation is based on the total
watts of continuous consumption. The costly factor will be how long the UPS is to supply power to the
server. No matter how long the UPS lasts it must be able to communicate with the server for an orderly
shut-down. Another option, or even addition, is a backup generator who also has the same restraints as an
UPS. The portal locking hardware is often overlooked with respect to a power outage but without power,
the field controller cannot actuate the lock.
Authentication Mechanisms; Multiple Authentication and Security Factors
One of the objectives of a PACS is to filter physical access to areas only to individuals who are authorized
to enter through an access control point. A second objective is to log access activity at an access control
point as well as of individuals. As described elsewhere, an airport operator has a wide variety of
authentication methods to choose from when deciding what is most suitable for the specific site and access
control points. Access credentials are created, issued and provisioned for appropriate access as determined
per local policy.
Generally, a PACS grants access to an individual presenting a valid, authorized credential to an access
control reader. This authentication mechanism is based on possession of a token (such as a card) that stores
a unique identifier, most often a numeric value, in the credential. The identifier is registered and provisioned
in the PACS. Alice’s credential contains an identifier that will cause the system to grant access to Alice at
the access control portals where she is authorized.
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