Possible Fly-in

I responded to him that Switzerland joined Schengen in 2008 and I didn't need any customs.

My last response was that my flight plan was in the system for more than 4 hours before arriving in Koblenz, so the authorities were aware* I was flying that day from Switzerland to Germany.

Sorry to say it, but both arguments are completely irrelevant in that context...

Re the forum fly-in, Colmar seems to tick a lot of boxes. Also, any destination in the western parts of Germany is just fine for me.

Sorry I should have added that this wasn't the first flight in and out of Switzerland for me. This was the first time someone told me I needed customs.

Can someone point me to the document telling me I need customs flying (to) from Switzerland?

I frankly don't understand what you mean. Switzerland is not part of the EU, so customs are always required when going to / from there.

Isn't the issue that Schengen allows for free travel of people, but not of goods and vehicles?

Greece operates it like that, so unless you walk or swim across the border to/from Greece, you have to use a Port of Entry. Only one Greek airport is an exception and I suspect it is a mistake... need to look up its AIP one day, now that Greece's is online.

It does make Switzerland's Schengen membership pretty worthless of course.

I agree with you Peter, but Switzerland is not EU. Officer you were very lucky, as landing on a non customs airport can be very expensive, because you have to tax the plane and pay a fine. It doesn't matter if it is PH registered or D or G reg. I have checked this with the German customs authority and they confirmed that. If you want I can forward you the email. German and Austrian customs are very strict.

I believe you all, that's not the point, but this is what I can find:

But the obligation to pass (your vehicle) through customs is not an aviation rule, so why seek it in the AIP? I reckon you'd rather find it in fiscal law. Like mdoerr I think you have been very very lucky up till now.

Re the forum fly-in, Colmar seems to tick a lot of boxes

A lot, but alas, not all: microlights are not accepted as visitors.

I checked my logbook and this year I had 4 flights to/from Switzerland. None of those included customs (not even at the Swiss side) and the first time I heard about it was in Koblenz.

Wow, you are taking a high risk here. Infringing customs regulations is a serious offence and there are hefty fines. One day they are going to get you and then they can dig out your past infringements and easily construct a criminal case (repeated offenses).

I am looking in the German and Swiss AIP, but I can't find the frase telling me I need customs.

The AIP is not a law text, it is just a compilation of useful information in an ICAO standard format. Also not knowing about a law/regulation will not help you against prosecution.

I could dig out the relevant German (= like the rest of the EU+Schengen) and Swiss laws but you will find a lot of information by just searching the web. Remember the news that the German island of Sylt lost its customs status and no longer accepts non EU/Schengen flights?

3 out of 4 flights were all from/to international airports with customs. But I didn't receive customs on any of them. This in contrary with my experience with travelling to the UK for example.

Is there any Swiss pilot here that can enlighten me? Why is customs necessary and do you alway pass them when flying from Switzerland to other parts of Europe?