Most passenger airplanes now have 8 doors, separated equally on both sides. However, if you regularly fly, you will realize that passengers are forced to get on and off the plane by the left door, whether by pipe or by ladder. The right door is always closed for a reason.


Not only for commercial aircraft but also for most of the transport and combat aircraft, passengers must board from the left door. Because related to conventions in the maritime industry from ancient to present, according to the structure of the ship, the starboard is placed where the rudder is, so passengers have to go up and down on the left side when the ship arrives at the port.


Similarly, the right side of the plane has enough doors like the left but only for emergencies. As usual, this side is where the ground staff arranges checked baggage, so passengers have to get up and down from the front and rear doors on the left side, whether by pipes or by ladder.


Previously, some aircraft allowed passengers to enter and exit at the right door. However, this caused many obstacles for the captain, who was always arranged to sit in the left of the cockpit, when hen he had to observe the outside and adjust the aircraft door to the position that matches the connecting pipe from the airport.


Moreover, this regulation has several issues of aviation safety. The aircraft must refuel on the right, so the separation of ground activities, such as luggage storage, fuel pumping, etc., with the welcome of guests will help minimize risks and also save time. In case you are allowed to board the plane from the right side, it is when you take a family plane, a small helicopter, or a propeller plane with only one door on the right. Meanwhile, passengers wait for the pilot to come first, then go in there later on.