So far every time I flew to the US, I remember having to go through extra security checks before boarding the flight - or had to go through pre-clearance in the case of flights from Canada. Do these checks exist in every single international airport or is airport security considered good enough in some airports that US-bound flights don't get a special treatment?

Practical reason for this question: I often have a very wide choice of transfer locations when flying to the US. If some of them don't have the annoying extra checks for US-bound flights, I'd be more inclined to choose them for my next trip.

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    My experience: there is not rule. From same airport (South America) I got once a check before boarding (to US), and all other times no checks. OTOH I had also second check in Europe (to Europe), so maybe it is just random second check. Jun 21 at 5:58
  • Relevant but not quite a duplicate: travel.stackexchange.com/questions/131041/… Jun 21 at 6:54
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    United has been particularly aggressive about this in the last two years or so. I don't recall anything with Icelandair and only minor questioning with Lufthansa.
    – Hilmar
    Jun 21 at 12:39

4 Answers 4


The airlines are held responsible for the passengers they bring into the US, and they are reluctant to believe that the local airport security checks are up to the TSA required checks in every detail; they do not however have supervisory input or any control on them, so they need to make their own.

My tip is to not fly from Munich; they are by far the worst and most annoying.

  • These are not at all the same checks as TSA is doing. In fact, in the US these checks are considered illegal.
    – littleadv
    Jun 21 at 3:45
  • @littleadv: but airlines are doing them because US rules. I'm not sure they are always for security (but more about border protection: vegetables, etc.). From some airports, crew must spray insecticide on plane (strictly regulated when, how, etc.) Jun 21 at 6:02
  • @GiacomoCatenazzi What US rules?
    – littleadv
    Jun 21 at 6:15
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    In 2017 the TSA introduced a load of new tests for flights to the USA: link. Although authorities are often reluctant to discuss precise security measures because it helps terrorists and criminals to know what's checked and what isn't.
    – Stuart F
    Jun 21 at 15:44
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    @Aganju i agree that it's farfetched but since much of the extra security I've encountered in the last couple of decades was indeed extra security rather than extra document checks I couldn't think what else you might have meant to say.
    – phoog
    Jun 21 at 17:39

I remember being at Warsaw Chopin in 2010 and witnessing a queue of Poles flying to Chicago.

Since we were in the regular transfer area (EU-non EU) I suspect they did not have to pass any additional screenings.

They still had to produce some kind of aďditional paperwork at the gate, or so it seemed.


Certain world airports have "Pre-clearance". This means there is a section of the airport that is cordoned off and inside the USA as far as immigration and customs are concerned. To get to the gate, you must clear US immigration and customs. But hey - no second Customs when you arrive.

Airlines that do not fly out of Pre-clearance gates will operate their own company immigration document check at boarding. This is required by law and the airline is fined very heavily if they bring someone to the country whose papers were not in order. You can't escape this, except at Pre-clearance airports.

Some non-pre-clearance international areas of airports destined for the USA will have additional security checks.

Some airports do not have airside passageways between all their many terminals, so arrivals needing to change terminals may need to exit and re-clear security. Often, so do international arrivals. This tends to happen to very successful old, but built-up airports like Detroit and LAX, you can't easily bulldoze the existing terminals and there isn't room on the property for a new "everything terminal".

Very small airports that fly the rubber-band airplanes (like Goose Bay, Scapa Flow or Lukla) will not be up to full "sterile area" standards, and their passengers will need to go through security again.

This all varies from route to route, so you have to check for each case.

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    I didn't downvote this, but it doesn't address the "extra checks" at non-preclearance airports, where in some cases US-bound flights are in a separate section of the international departures area requiring an additional security screening, and in other cases there is just an additional immigration document check done at the gate.
    – phoog
    Jun 21 at 8:31

My understanding is that you're asking about the additional security checks within the airside, when you get to the boarding gate.

I believe this is up to the airline and depends on location.

The only two airports where I have not encountered these checks were:

  • TLV - everyone goes through them, so no need to single out US-bound flights
  • PEK - Given the absolute surveillance state that is PRC, interviewing passengers at the gate is probably redundant.

Other than that, I've encountered varying degrees of extra security for US-bound flights in any other airport I've been to.

I've been flying internationally with United in the last several years and they had them everywhere (mostly in Europe). I flew with British Airways from LHR once, and they just had a documents check and a quick in-person assessment (I didn't see anyone being taken aside for further interview). Swiss in ZRH also had a full blown security check for US-bound flights at the gate when I flew with them a couple of years ago (I believe they shared infrastructure with United for these checks).

Just to clarify, these are not "TSA-equivalent" checks. In fact, TSA checks are pretty ineffective, when it comes to human factor, since there's no interviewing or profiling involved (or even allowed). There were some changes suggested by GAO in 2019, but given the political climate in the US they can only go so far.

Personal opinion below (although I've seen no evidence otherwise and quite a lot of evidence to support this opinion):

While these checks are annoying, they're extremely effective. During the mid-20th century there's been a lot of incidents of plane hijackings and bombs on board (e.g.: the PanAm incident), and these checks were designed to prevent the recurrence of such (e.g.: The El Al incident).

The fact that planes' hijackings are rare nowadays goes to show that these checks work, both in prevention and deteral. If 9/11 has taught us anything is that given the opportunity someone will take it.

For those readers who hadn't lived during the 70s and 80s of the last century, a more recent reminder of why these checks are important would be the "underwear bomber". The perpetrator boarded a US-bound flight in Amsterdam, passing all the post-9/11 security measures, and successfully bringing an explosive device on-board. This happened in 2009, and it is due to this incident that the US-bound flights now receive a bit extra security.

US flights are not the only ones, similar checks are routine for decades for all the flights to Israel (and from Israel), and for the same reason.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Willeke
    Jun 21 at 8:08

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