What is a key indicator of potential criminal activity at an airport?

The identification of unusual behavior or a lack of a travel itinerary as a key indicator of potential criminal activity at an airport is grounded in the understanding of security protocols and risk assessment. Airports are high-security areas where certain behaviors can signal a deviation from the norm, which might suggest suspicious activity.

When individuals do not have a clear travel itinerary, it raises questions about their purpose at the airport. Typically, travelers will have specific plans—destination, purpose of travel, and a clear itinerary. A lack of these can indicate that the person may not be a legitimate traveler and could potentially be involved in activities like smuggling, terrorism, or other criminal acts.

Moreover, unusual behavior encompasses a range of activities that might include nervousness, avoidance of security personnel, or interaction that's inconsistent with typical passenger behavior. Security personnel are trained to spot these behaviors, as they can provide leads for further investigation into potential threats.

On the other hand, options like unusual weather patterns, delayed flights, and high passenger volumes do not directly pertain to criminal activity. While they may lead to operational challenges or discomfort for travelers, they are not indicators of threats or malicious intent in the same way unusual behavior is.