After reading many of the great questions that have come in to "Talk to TSA" I think the best one to start off with is a commonly asked one: are liquids still a threat? The short answer is yes. I can appreciate how someone might wonder why their bottle of water is considered a threat. Having worked at the FBI back in 2006 when the UK liquids plot was disrupted, I understand why TSA’s procedures are in place. To answer your question, I’m going to tell you as much as I can about why the 3-1-1 liquids rule is necessary without getting into classified information.
On August, 10 2006, I was serving as the Deputy Director at the FBI. The FBI worked closely with other US Intelligence Community agencies and our close partners in the UK to disrupt the plot to blow up several airliners flying from the UK to the US. I know of the real and present threat those terrorists posed using chemicals disguised as everyday consumer items such as sodas and water. If undetected, I believe there is a high likelihood the terrorists would have killed hundreds of people that day. That's why we limit the amount of liquids you can bring on a plane.
The challenge with liquids and the vulnerability that terrorists tried to exploit in August 2006 is that liquid explosives don't look any different than regular liquids on the X-ray monitor. There is no way to tell one from the other without removing every liquid from every passenger's bag and testing it. I'm sure you could imagine the gridlock that would ensue if our officers had to test every liquid that came through the checkpoint. This led to an immediate ban on all liquids on August 10, 2006 because of the threat that was uncovered. Extensive testing started immediately to determine if there was a way liquids could be brought on board without posing a risk, because the total ban wasn't sustainable in the long term. These tests were conducted by multiple government agencies, national laboratories and other nations, and the end result was the 3-1-1 formulation: 3.4 ounce (100ml) containers, inside a 1-quart clear, plastic zip-top bag, 1 bag per passenger.
The sealed baggie limits the total volume of liquid per passenger and keeps all the liquids in one place so officers can get a good look at them.
Some have speculated on the possibility that several passengers each carrying a baggie full of 3.4 oz. bottles full of liquid explosives could all go through the checkpoint and combine their liquids in a larger bottle. That's a reasonable question. It's easy to dismiss 3-1-1 if you don't understand why this scenario is highly unlikely. Liquid explosives are extremely volatile and it was the general consensus of top explosives experts that it would be nearly impossible to create a successful explosive combining a small amount of liquids in a larger container on an airplane.
We understand that 3-1-1 is an inconvenience. But it's also an inconvenience to terrorists and significantly drops their chances of getting a liquid explosive on an airplane. The liquids rule continues to be a necessary step because current intelligence shows that liquids are still a threat, and until TSA has the technology to screen liquids at checkpoints, the only other alternative is to ban all liquids. We're not going to do that. TSA is getting closer to finalizing upgraded software for X-rays that will allow liquids to be screened. Until this happens, we will continue with 3-1-1 to keep you safe when you fly.
In the meantime, please continue using the 3-1-1 liquids rule, or put your liquids in your checked baggage.
I hope this has answered your questions on whether or not liquids are a threat and why we require the baggie.
John S. Pistole