There’s a reason why you always board a plane on the left side, regardless of the airline or your seat class. It all goes back to maritime traditions and the placement of the steering oar on ships. Early airplanes adopted this practice, and as the industry grew and airports became busier, left-hand boarding became the norm for efficiency and safety. This arrangement allows pilots to better judge distances while taxiing to the gate, and it keeps ground crew out of the way of passengers.