What is the root cause?

I was on a job trip, where the return journey did not go according to plan.

The result was a missed air plane, and Hertz received a damaged car in return.

What really happened and what was the root cause?

Can 5 Why and Fishbone help us understand the root causes?

We visited customers at Meløy, (3 hours drive from the closest airport Bodø). Normally you can drive, but due to a rockslide the road was blocked, and a ferry was the only alternative.

We planned enough time to catch the ferry, but did not predict how many people who planned on travelling with the same ferry as us. Waiting for the Ferry, the truck in front of us backed and hit our car. Luckily it did not cause serious damage to the car or us. 

The ferry could not fit all cars. In fact, we were the only car they could not fit at the extra ferry arriving shortly after the first ferry left. Due to this we had to wait one hour for the next ferry, resulting in minimum margin to catch the air plane.

Arriving at the ferry destination, the crew gave us signal to leave the ferry. It ended with another crash…

The ferry exit was not connected to the inlet ramp. It was 30-40 cm above. The car got stuck and we had to get some strong men to help us release the car and get off the ferry.

Our time schedule is really tight and we end up missing the air plane. 

What was the root cause?

How about doing a "5 WHY" analysis and use a Fishbone diagram to structure the root causes? 

An incident may have serveral causes or a combination of causes.  A Fishbone diagram (also called Cause and Effect diagram), can be used to identify possible causes due to People, Methods, Machines, Materials, Measurements and Environment. The Fishbone diagram below is a suggestion. You might find other causes!