I found this most unusual. Is this a HEL thing, or a Schengen thing?
It depends on the airport and how the traffic flow is set up. There are some airports where you go through connections security sometimes, but not others.
First time I went through DOH, I didn't get screened for the connection, 2nd time I did.
Some departures from DXB and DOH got screened once, others twice.
Connections through most US airports can be made without having to go through TSA again. It's only International flights arriving into the US where you have to go through TSA for the connection as everyone has to go landside regardless of type of connection.
at ORD, I>I connection means both CBP and TSA regardless of I departure terminal (all International arrivals at ORD at T5, then some flights get towed over to the other terminals for departure). D>I can be either no TSA or TSA again, depending on if you need to use the train to get to T5 or can use the bus.
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JFK can't seem to understand what "can't hold arms up" means. When someone can't hold their arms up for the body scanner, they are meant to be sent through the metal detector and then have an hand ETD swab. That has happened this trip at PDX, LAX (twice), DEN and DTW. It also happened at SYD on my prior trip.
No body scanner at YVR transborder, HND , DOH or VIE. Avoided scanners at MEL, LHR , and 2nd SYD.
Yet, JFK just treated "can't hold arms up" as "opt out" and did the normal over reaction pat down rather then what they are meant to do (despite telling 2 of them that I wasn't opting out, I couldn't hold my arms up).
I got told off at LHR. One time I get told that I didn't need my tablet out. Next time I got told I do.