Who to complain to about the speed of airport security at Frankfurt?

Let me try to handle your implicit question, which I assume is "what can I do to prevent this next time?".

If you are in a line for security, and think there is a danger of you missing a flight, then the best way to deal with it is to talk to whoever is directing the lines. There is almost always someone, and if they agree that you might miss your flight they will often direct you to the front of the line. In fact if you think you are going to miss a flight, asking airport staff (or airline staff) for help as soon as possible is a good idea. Having passengers miss a flight is a problem for both airline and airport, and they will frequently make great efforts to get you to your gate on time if they know, and airlines are more likely to hold a flight a few minutes if they know you are on your way.

Waiting until you are at the head of the line and then telling the staff that their behaviour is bad is not going to help at all. As well as all the reasons o.m. said, the speed of a security line is usually limited by the number of bags that can be put through the machine. Having more people present, or having them being grim-faced (instead of laughing) or silent (instead of speaking) will not help at all.

While police will be present at the airport, actual checks may be done by contractors.

• The companies who provide security services are under pressure to keep costs low.
• These security contractors are usually not well paid, which does not increase their motivation or the competence of the available workers.
• That being said, they are entitled to rest breaks, etc. You have no idea when they went on shift, when they had scheduled breaks, and when they were supposed to go off shift.

From my experiences with airports and airlines, often the best way is the 'public' image. Emails can be ignored, phone calls diverted (not saying this is always the case), but social media managers seem to have their job description as getting 'angry' or 'bitter' or whatever negative opinions off twitter especially ASAP into private messages.

So for example, in this case I'd send a tweet out and mention Airport_FRA in it, and hashtag #frankfurtairport. That way at least the mention might get passed on.

I don't remember the source but about a year ago I read an article written by airport staff and it included the answer to this question: "What to do if I'm short on time and need to pass through security to get to my connecting flight.". Basically the answer was that you need to go to the security staff (there's usually someone patrolling the queues or similar) and explain your situation. Do not go to the front of line and ask the people at the checkpoint. They're too busy.

As the airlines incurs a lot of loss from people needing to be rebooked due to missed flights, they are constantly pushing on the airport and its security staff to perform as efficiently as possible, and the security staff knows that the less people getting rebooked due to a missed connection, the better for them, so they will be eager to help you.

There's usually a semi-closed position or a VIP-position that they'll employ to service you right away. But you really need to be late yet still have a decent chance at making your connection for this to work so they will check your bording pass before doing anything and they still might refuse to help.

"I had a connection for 1 hour and 10 minutes"

That is too short to make an international connection. I assume your connection was international because you said you were stuck for two days before getting an alternate. Try claiming on your travel insurance, but they will probably not accept it. I suggest you complain to whom ever booked your ticket, you might get lucky.

Transfer guidelines and useful tips for Frankfurt Airport are published here: https://www.frankfurt-airport.com/en/flights---more/transfer.detail.suffix.html/article/flights-and-more/services-a-z/easy-travel/transfer-at-fra.html#fratransfer and it includes ensuring you have reasonable time to clear security which includes allowing for the fact an incoming flight can be late! From your description, Security were doing their job and operating within their published guidelines so it looks like there is no reasonable complaint you can make in this situation but if you do want to follow it up, security would be airport employees, so you can contact the airport authorities themselves in the first instance at feedback@fraport.de

In addition to Mark's answer, a post mentioning the airline may also be helpful. While it's not necessarily the airline's fault, they have more power to put pressure on the airport and/or security contractors to do their jobs efficiently.

Missed connections are expensive and inconvenient not only to the passengers, but also to the airlines. Security causing passengers to unnecessarily miss a flight is something that (good) airline do care about. In addition to the bad PR the airline gets from passengers missing flights, having to re-accommodate passengers on later flights, put them up in hotels, pay for delay expenses or refund tickets, etc. are large costs to the airline. There always going to be a few incidents everywhere, but if it's something that's becoming a common pattern at an airport, an airline (especially a major one that represents a lot of the airport's traffic) can put a lot of pressure on the right people to get things done more efficiently.

If the security contractors aren't concerned enough with helping to keep the airport operations running smoothly, the airline can push to either get the contractor to start caring or replace them with one that does care.