The objective of this panel is to assess technologies deployed to improve aviation security, both to protect passenger aircraft from explosives and to protect aircraft from damage from an onboard explosion. Explosives can be placed aboard an aircraft via several vectors, including baggage. In this chapter the typical processes for handling carry-on and checked baggage in a secure environment are described, including the use of unit-loading devices (ULDs) as a basis for the discussion of the operational issues for using HULDs (hardened unit-loading devices) as part of an overall aviation security plan (e.g., TAAS).
The six typical vectors for introducing explosives are: passengers (on person); passenger carry-on baggage; passenger checked baggage; cargo originating from known, unknown, or consolidated shippers; courier bags; and mail. More subversive vectors include: crew members (e.g., pilots or flight attendants); an intentional or accidental security bypass; food catering service or meal cart; duty-free items; cleaning crew; and service crew (e.g., mechanics, fuelers, baggage handlers). To prevent the introduction of an explosive, all of these vectors must be secure. However, the focus of this panel is on passenger carry-on and checked baggage. The security devices used to prevent the introduction of explosives via the typical vectors are shown in Figure 4-1.
Movement of Baggage and Cargo
Approximately 50 percent of all passenger baggage is carried onto airplanes as carry-on baggage; the other 50 percent is checked at the curb, at the ticket counter, or at the gate. The actual distribution of baggage varies by type of aircraft (see Box 4-1). All carry-on baggage is screened at a security checkpoint by an x-ray scanner prior to being brought aboard an aircraft; in some cases, bags are further investigated with a trace explosives-detection device or searched physically (Figure 4-2). Once aboard an aircraft, carry-on baggage is stowed by the passenger in an overhead bin or under a seat.
Checked baggage is sent to a bag room where it is sorted in a variety of ways, depending on the airline and airport.
The panel observed the sorting and loading of baggage and cargo by more than 10 airlines at Los Angeles International Airport, San Francisco International Airport, and John F. Kennedy International Airport for various types of aircraft and for domestic and international destinations. The purpose of these observations was to assess the synergy of the baggage-handling system with planned screening procedures and the feasibility of using HULDs.
Most of the time, checked baggage is sorted either manually or by automated card readers and routed to the bag "make-up" area for the appropriate flight. In the make-up area, the bags for a particular flight are gathered, sorted by class of service and transshipment, and either loaded into a ULD that is then loaded onto the aircraft (containerized method) or loaded manually onto the aircraft one piece at a time using a baggage cart and conveyer-belt system (bulk method). The bulk method is mainly used for narrow-body aircraft and the containerized method for wide-body aircraft. However, both methods are sometimes used for both types of aircraft. For example, ULDs are used for a few narrow-body aircraft, such as some Airbus A320 and Boeing DC-8 aircraft.
Passenger with a Checked Bag on a Domestic Flight
A passenger for a domestic flight can check bags at the curb, the ticket counter, or the gate. If the bag is checked at the ticket counter,1 the passenger is asked three questions pertaining to the contents and control of the bag (Figure 4-3). The passenger is also subjected to CAPS (computer-assisted passenger screening). If the passenger is determined by CAPS to be a selectee, he or she is also subject to PPBM (positive passenger-bag matching). The bag will then be loaded directly onto the plane if it is a narrow-body plane or placed in a ULD and loaded onto the plane if it is a wide-body plane. If the bag is checked at the gate, PPBM and CAPS are not used. However, bags checked at the gate will have been screened by x-ray radiography and, possibly, trace explosives-detection equipment (Figure 4-4).
Passenger with a Checked Bag on an International Flight
A passenger for an international flight usually checks bags at the ticket counter. The passenger is asked questions pertaining to the contents and control of the bags and is subjected to CAPS and PPBM (Figure 4-5). Checked bags are then subject to examination by an explosives-detection device or a certified EDS or are physically searched.2 The bags
1 Passengers who check in at the curb or gate are also asked security questions. If a passenger trying to check bags at the curb is determined to be a selectee, he or she is asked to check the bags at the ticket counter.
2 Typically this is only applicable to the departure city (the city from which the plane departs for a foreign country) and not for baggage that originates on a domestic flight and is transferred to an international flight.
are then loaded directly onto the plane if it is a narrow-body plane or placed in a ULD and then onto the plane if it is a wide-body plane.
The containerized luggage system is used mainly on wide-body aircraft to facilitate the rapid movement and organization of large quantities of baggage and cargo, minimize on-loading and off-loading times, and facilitate transshipments. The basic components of the containerized luggage system are ULDs, also referred to as containers or cans (see Figure 4-6). ULDs are used to hold, separate, load, and unload passenger baggage and cargo. They come in a variety of sizes and materials, depending on the application (e.g., type of load [baggage or cargo], type of aircraft, deck location, and transshipment needs). ULD sizes are distinguished mainly by the type of aircraft and are designated by the ''LD" nomenclature. The construction material of these containers varies from aluminum to polycarbonate to heavy-duty cardboard. In all, there are an estimated 200 or more combinations of ULD sizes, materials, and manufacturers. The containerized luggage system also includes specialized container carts and aircraft loading devices.
Use of Hardened Unit-Loading Devices
During the panel's airport visits, several procedures and practices were observed that could affect the combined use of security screening devices and HULDs within a defined TAAS. The method of loading ULDs varies from airline to airline, and even from airport to airport by the same airline. Some airlines stand the bags up on the floor of the ULD (Figure 4-6); others lay them flat. All airlines observed by the panel tried to maximize the bag count in each container (i.e., load all the way to the top). However, the bag count can vary from 30 to 50 bags per container, depending on the destination of the flight and the average size of the bags (bag size appears to be a function of the local passenger culture and destination). Most airlines separate bags by transfer destination, as well as by class (first class, business class, and coach class). The first-class and business-class ULDs are loaded last and unloaded first. One airline, however, used a separate ULD for the bags of CAPS selectees, which was loaded last.
All ULDs look and function in similar ways. The location of the ULD doors and accessibility for loading are also similar. If the airline route (e.g., Los Angeles to Sydney, Australia) is extremely weight sensitive, only lightweight (e.g., cardboard) ULDs are used. Airlines are very sensitive
to the weight issue. For example, contractual requirements with the U.S. Postal Service dictate that any weight overload will usually result in the removal of passengers rather than the removal of mail.
Seventy-five percent of the commercial airline fleet is narrow-body aircraft, which means that 80 percent of baggage travels in bulk cargo holds or in the passenger cabin and only 20 percent in ULD containers. Therefore, if HULDs were used for 100 percent of the wide-body fleet, they would still only account for approximately 20 percent of all passenger luggage. The development and use of HULDs are discussed in Chapter 5.