In fact, boarding the ship from the left side followed the old habit of shipping industry, just as the width of the railway track in the Roman Empire was determined by the width of the chariot. In the past, ships usually docked from the left. Because the rudder of some ships is usually installed on the right side, the rudder will hinder berthing from the right side. Other ships are affected by the direction of propeller rotation, so it is easier to dock from the left side than from the right side. So this old habit is still used in the aviation industry today. For example, an A380 plane with more than ten doors boarded the plane from the left. On the left is also the design of the airport covered bridge. When the plane is parked in the parking lot, approach the plane slowly from the left. The right door of the plane is usually the service door, and the dining car and luggage are sent to the plane from the right door. For example, the right rear hatch is specially designed for catering vehicles and service vehicles. Our luggage compartments are generally designed at the front and at the bottom right. In addition, most of the aircraft refueling comes from the refueling port below the right wing. In order to standardize, all doors of the aircraft are opened on the left side, which is convenient for the unified design of covered bridges, passenger elevators and oil tankers. Only by unifying standards can we ensure where the plane flies. When the plane is on the ground, the planning of each place is to facilitate the service vehicles to approach the plane, rather than interfere with each other. At the beginning of design, the left front door was reserved for the bridge or passenger elevator car. Each door has its own function or there are other facilities nearby. For example, the lower part of the right front door is reserved for power cars. I didn't expect so many things when designing, and many of them were made casually. Aircraft parts are also counted from left to right, such as wheels, spoilers, slats and fuel tanks. So according to the order from left to right and from front to back, it is no problem to board the plane from the left front door. From the plane, slowly to the fighters of World War II, they gradually began to get used to boarding the plane from the left, knowing that there was no difference between the fighters on the left and the fighters on the right. This is just a habit gradually formed. It is far-fetched to extend the habit of landing on the left side of the ship to the plane. For convenience, board the plane from the left. So, what are the functions of other doors except the boarding gate? Every door on the plane has its own function, except the boarding gate. The right and rear doors are the entrances and exits of aviation food trucks and service trucks. In addition, every hatch on the plane acts as an emergency door. In an emergency, it can be used as an escape route. My personal feeling is that when I landed and ran at N airports, I saw that most runways were designed in the north-south direction. Generally speaking, the airport should not be built in the east-west direction, because it is necessary to avoid glare caused by direct sunlight, which will affect the flight, thus affecting the plane's up and down flight. Besides, getting on a plane is like riding a bike from left to left! habit