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.

  • 3
    You're transferring from a domestic flight to a non-schengen international flight, so I think you will need to go through customs at Madrid airport. It will depend on which terminals your flights arrive and depart, as well as whether you already have a boarding pass or not and/or if your luggage is checked through to your final destination if you can transfer air-side or will be leaving the secure zone and will need to pass security again. - So: no definitive answer is possible with the limited information you provide.
    – diya
    Commented Nov 28, 2022 at 16:52
  • @diya I edited my question with more details
    – Shmiel
    Commented Nov 30, 2022 at 13:51
  • 1
    The question assumes that the security process at all airports is identical. It isn't. The security process depends on the airport, the itinerary, the airline, the nationality of the traveler, the rules of the government entity or business conducts the evaluation, and probably other factors too. Thus, if the UK security authorities think the security process at Alicante is lacking, you could well be required to pass security again as you transit in Madrid. Commented Nov 30, 2022 at 15:41
  • @DavidSupportsMonica There are direct flights between Alicante and UK without any additional security checks, so it must be Madrid doesn't trust security in Alicante, which doesn't make sense to me.
    – Shmiel
    Commented Nov 30, 2022 at 16:20
  • 2
    Not necessarily. Perhaps the UK authorities think the transfer from T4 to T4S in Madrid is somehow insecure. Or sometimes (depending on flight schedules, say) the security at Alicante is lacking: just because some flights go direct from Alicante to LHR doesn't mean all flights departing Alicante can do so. In any event, you seem focused on being able to find a reason that satisfies you. That may be an impossible goal, and it will not affect your travel: to fly this route, you'll have to jump whatever hurdles are placed before you. Commented Nov 30, 2022 at 17:47

2 Answers 2


To allow an interchange without re-clearing security a few things must hold.

  1. The airport you are interchanging at must trust the airport you arrived from. Different countries have different policies on this with some being more trusting than others.
  2. The airline and destination airport must trust the "regular" security of the interchange airport. Some destinations and airlines insist on extra security checks in addition to the "normal" airport security.
  3. The passengers must not have access to their hold luggage while in the secure area (as hold luggage can contain items forbidden in the cabin).
  4. The airport must be willing and able to keep the flow of passengers who do not require security checks separate from those who do require security checks. Each segregated passenger flow an airport adds costs money, so the airport has to balance the cost of extra security checks against the cost of segregating passenger flows.

As you're transferring from an inter-Schengen flight to a flight leaving the Schengen area, you're going to have to go through passport check at the very least.

Customs is USUALLY only applicable to arriving passengers.

Security depends on the airport and even the terminal. Some have it once on entering the airport, others have it on entering the terminal, others still at every gate, and I've been to airports that had all three systems in place, where you went through security screening at least 3 times before boarding your flight.

I'm not familiar with the situation at Madrid Barajas, but I'd be surprised if you can travel from one terminal to another without some form of security check.

So you're likely going to have to go through security, especially if your departing flight is from a different terminal from the arriving one.

  • Thanks for this answer, but see my edit on what happened in the end for this specific route and airport.
    – Shmiel
    Commented Jan 1, 2023 at 14:01

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .