Why is liquid prohibited but tax-free purchases at the counter allowed to be taken on board?

All goods in this area have been thoroughly inspected to ensure they do not contain substances that could be used to make bombs.

Why is liquid prohibited but tax-free purchases at the counter allowed to be taken on board?

Liquid is on the list of items banned from being carried onto airplanes by airlines, for the sake of ensuring aviation security. Anyone who frequently travels by plane is aware of this. However, have you ever wondered why you can bring beverages or perfume bought in the duty-free area onto the plane, but the same items (same origin, same brand) brought from outside the security checkpoint are prohibited? This is a common question for many people, but not everyone knows the exact reason.

First, let's understand the reason behind this ban. In 2006, the first widespread ban on carrying liquids onto airplanes was issued worldwide after a plot to bomb using liquids was thwarted by the UK police. The amount of liquid found on a flight from the UK to North America was estimated to be capable of causing a large explosion, resulting in more severe damage than the 9/11 incident not long before. Prior to that, another bus explosion was discovered in 2005. The bomb found contained liquid components.

This incident led all airlines to tighten security measures rigorously, especially for liquids carried onto airplanes. Specifically, these liquid containers must be divided into smaller ones, each containing less than 100 ml, with a total volume not exceeding one liter.

This regulation aims to control and prevent the transportation of potentially explosive liquids such as nitroglycerin, which could be disguised as water bottles or mixed into familiar solutions like shower gel, shampoo, or mouthwash. At that time, the security scanners at checkpoints could only detect liquid but couldn't identify the composition of the solution.

Splitting into 100ml containers has been proven by scientists to reduce the level of danger. In necessary cases, passengers are still allowed to carry liquids but they must be divided. According to experts at the US Transportation Security Administration, if these are disguised by malicious elements as explosives, with such small divided volumes, the harm will be reduced, and homemade bomb explosion potential may even be eliminated.

Many wonder, why aren't beverages or multiple perfumes, cosmetics totaling more than a liter banned after passing security checkpoints? In reality, all goods in this area (such as duty-free shops) have undergone rigorous inspections to ensure they do not contain substances that can be made into bombs or mines. Moreover, this also significantly boosts revenue for these shops.

However, after over 10 years of implementation, this regulation has gradually been relaxed. Specifically, for domestic passengers in Vietnam, since May 2016, travelers can bring liquids freely as long as they comply with the size and weight regulations for carry-on baggage. This regulation has also been flexible in many countries as nowadays, security screening equipment at checkpoints has become more advanced, capable of distinguishing harmless substances from explosives.

By Nguyên Chi/Ngôi sao

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Reference: Travel Handbook by Mytour