Not all, but the majority of airplanes have the main passenger entrance on the left side. There are 3 theories explaining this fact.
- Theory #1. The right side is for the luggage (cargo hatches are also on the right), so it’s not safe for passengers.
- Theory #2. Some people say that it’s a tradition from the past: ship ramps were always on the left.
- Theory #3. The capitan of an aircraft used to sit on the left. The location of the passenger door allowed them to better park the plane at the passenger area.