You may have noticed that passengers board planes mostly from the left side, well the tradition is as old as the aviation industry.
But then why do we usually enter the plane from the left side?
Number one explanation is the fact that pilot sits on the left, and needs to be able to accurately align the plane door with the terminal for people to exit.
Another explanation is that the ground crew fuels the plane on the right side, so keeping passengers to the left gives them freedom to work.
Well designers planned pioneering airports so that planes could taxi in front of the terminal and disembark travelers. It was helpful for the captain to make judgments about wing clearance from the terminal building and to put the plane door in front of the terminal doors. Some early systems had right-side doors into the cabin. However, the pilot did not have the same unobstructed view.
According a Boeing 787 captain, he said the service doors on the right-hand side are smaller to keep more rigidity in the plane’s structure. The larger the door, the more reinforcement is needed around its composition. Therefore, since passengers were passing through the left-hand side, it made sense for the captain to also sit on the left-hand side to maneuver the aircraft to a standstill.
The Civil Aviation Authority summarizes this practice as being a necessity when it comes to safety. Altogether, it makes sense to separate passengers from the professional activity that usually occurs on the other side of the plane.(simpleflying)
Passenger movement is also better to be away from other activities such as unloading baggage and cargo. At times, these jobs require plenty of space and workers. So, having passenger activity on the left-hand side allows more room for movement.
The process of boarding on the left can be traced back to naval practices. Ships have a port, which is on the left side and a starboard, which is on the right side. Passengers would embark and disembark on the port side. Subsequently, since planes are an evolution of passenger travel, there was a natural continuation of these practices.
Nonetheless, there are exceptions to the rule. For instance, fliers board several smaller planes, such as the Mooney M-20, from the right-hand side. This process allows the pilot to enter before the passenger sitting adjacent. Additionally, in times of emergencies or inconvenience, there may be situations where it would make sense to use a larger aircraft’s right door for customers.
Altogether, regardless of the origin of this practice, it makes logistical sense to board on the left-hand side. If opposite patterns start to emerge, it could be costly to adjust to the new systems.
Culled from simpleflying.com