Screening of Passengers, Cabin Baggage and Hold Baggage
The screening process
Screening is a systematic process, not a single machine. It combines document and boarding pass verification, passenger interview or behaviour observation where permitted, walk-through metal detection, body search or body scanning, X-ray of cabin baggage, and explosive detection for hold baggage, supported by trace detection and random selection.
Candidates must understand the technology in principle. X-ray produces a two-dimensional image in which materials are colour-coded by density and atomic number; operators look for shape, density and anomalies rather than memorised images. Metal detectors respond to ferrous and conductive materials. Explosive detection systems analyse density and other properties, while trace detection looks for residues.
Prohibited articles and the concept of sterile area
Prohibited articles are defined nationally and internationally. The point of screening is to prevent them entering the sterile area and the aircraft. Once a person has been screened, they must not come into contact with unscreened persons or items; if they do, re-screening is required.
Traps
- Confusing screening (a filter applied to everyone) with search (a targeted physical examination).
- Forgetting that cabin and hold baggage have different threat profiles and therefore different technologies.
- Ignoring the human element: alarm resolution, image interpretation and vigilance are where most failures occur.
Worked example
An X-ray operator sees an organic-density mass with a wire and a power source. The correct response is not to guess the item but to apply alarm resolution: stop the bag, isolate it, and resolve by search or further examination. The rule of thumb is: when in doubt, resolve it out; never clear an unresolved alarm on assumption.