I have a flight from Alicante (ALC) Spain to London Heathrow, with a layover in Madrid Spain, will I need to go through security again in Madrid? Or because it's in same country there will be no additional checks when connecting without leaving the airport?
Both flights are with Iberia, arrival is in Terminal 4, and departure is Terminal 4S, which is basically same terminal.
My question is why I would need to pass security, and throwing away liquids, which I just got from Alicante. Don't they trust security in other airport from same country?
I decided to update in question what happened in the end, (I'm not adding this as answer because this question should be in general not specific for this route and airport).
I arrived in Madrid airport terminal 4, and there are signposts to terminal 4s, which is international departures, you go to a train transit, and there is passport control only without any security checks, so in my case the answer is:
There are no security checks when transiting in Madrid from terminal 4 to terminal 4s.