Is it possible or not?
When me left Germany in Feb 2017, it was not clear if it is possible to fly from USA to Cuba without the right visa. We tried to find informations online, but it was not clear at all.
If you travel from USA to Cuba u need offically a real visa, like the Americans do. For that u have to have a certein reson from a catalogue of 12 resons. You have to apply this visa before u travel.
BUT this is just the official way which seems not longer being enforced.
We bought the touristcard, every tourist has to have, in Germany. It´s very easy to get, you can mail order it, the cheapest way is if you fill it out yourself. At the airport in Miami you have to present it at the desk.
So result: (april 2017)
It is possible to fly with a valid german Touristcard (with a stamp on the back) to Cuba from Miami!
And we also haven´t had to present a return ticket, but can´t guarantee that this is normal.