Every airline is different, so when it comes to long-distance travelling most of us have a favourite carrier or company we prefer to fly with. 

Whether it’s the comfier seating, tastier food, better entertainment, more legroom or better service, every airline — and airplane — is different. 

However, when it comes to the design of the plane, there’s one thing that almost all aircraft have in common. 

Read more: Why not to include your middle name when making a booking

If you’re a frequent flier you may have noticed that most airplanes require passengers to board and disembark from the left-hand side. 

Commercial airline pilot Andrew Stagg wrote on website Quora that the reason for this is tied to hundreds of years of nautical history. 

“I believe the reasoning goes back to ships, which have a port (left) and starboard (right) side. The word starboard comes from “steerboard” which referred to a board similar to a rudder on the right of ship,” he said.

 “The placement of this board required that the port side was the one you would embark and disembark from, so most airplane and jetway designers followed the same convention.”

Read more: The simple way to get upgraded to first class

Private plane pilot Graham Harrison added that other practical reasons also come into play.

“Think about all the other things that have to happen during a turnaround. Baggage needs to be unloaded and loaded, fuel needs to be loaded, food and drink needs to be loaded,” he explained.  

 “Having all those things in similar places on the same side of every plane means people know where to go.”

It’s doubtful airlines would ever change the way they design their planes now, with all modern airports accounting for disembarkment the left-hand side.

Were you aware of the reason why passengers always board the plane on the left-hand side? Let us know in the comments section below.