Several foreign airports have US Customs and Border Protection (CBP) Preclearance facilities, where you clear immigration prior to boarding your US-bound flight. I recently flew Aer Lingus from Dublin (DUB) to Boston (BOS), and Ireland is the only country in Europe to have such a facility.

I’ve been through these facilities several times before, but there were a couple of things I found strange, and I’m curious if anyone has any insights.

At US Preclearance facilities, it’s common to have to clear security through a dedicated checkpoint before you pass through US immigration. These security checkpoints are typically separate from the standard security checkpoints at the airport, and I’ve been through these many times before, at airports like Abu Dhabi (AUH), Nassau (NAS), Toronto (YYZ), etc.

However, the security screening in Dublin was different than what I’ve seen before. After entering the Preclearance facility, most passengers have to go through a security screening process (in addition to whichever one they previously went through, whether it was in Dublin or at another airport).

But here’s what I can’t make sense of — all bags had to be placed onto an x-ray machine and be screened, while there was no metal detector or body scanning machine. So while all bags were thoroughly screened (including needing to remove laptops), passengers weren’t checked in any way.

That… ummm… doesn’t make a whole lot of sense to me, so what am I missing? If you’re carrying anything prohibited, you’d simply keep it on your person, rather than in your bag. Is this actually an approved screening method, are they running a rogue operation, or what’s going on?

Perhaps the US thinks that a European Union airport is up to the standard screening requirements for the US, so perhaps as thorough of a screening isn’t needed. But what’s the point of doing any screening if it’s literally only of bags and not of a person? And for what it’s worth, this wasn’t some sort of agricultural screening (as you might find in Hawaii), based on the things that had to be removed from bags.

Some people get to skip the security checkpoint altogether?

Here’s the second element to this security screening that surprised me. As you enter the US Preclearance facility in Dublin, your boarding pass is checked.

A vast majority of the passengers seemed to be directed to the standard security line, while a small percentage of passengers were directed straight into the immigration queue, bypassing the security check.

Pardon my curiosity, but does anyone know what’s going on here? For what it’s worth, it’s not like I had “SSSS” on my boarding pass, or anything, so it’s not that the security line was for those who needed secondary screening.

I tried to ask one of the people working there what the situation was, but I didn’t get a good answer. It doesn’t matter in any way, but this one stumped me — I thought I fully understood how US Preclearance facilities work, but this one was unlike the others that I’ve experienced.

Bottom line

While I’ve traveled through US Preclearance facilities many times before, the Dublin experience was different than I remember, particularly with the security check.

It’s standard to have to go through a dedicated security checkpoint for US-bound flights, but here only bags were scanned, and not people, which just seems odd. Furthermore, some people were able to skip that completely.

Since Ireland has the only Preclearance facilities in the European Union, my theory is that maybe screening doesn’t have to be as stringent as it does at other airports. That being said, I’d still love to understand if this is actually how the system is intended to work, or what was going on here.

Can anyone make sense of the quirks of the Dublin Preclearance facility?