Reflect on all the flights you have experienced. Consider the aerobridges or the mobile staircases that have been brought to the rear exits. What common elements can you identify? Perhaps it was the crowd of people moving forward, passengers adjusting their carry-ons, or an influencer causing delays for a perfect exit photo. There might have been someone speaking too loudly on their phone as well.

However, one constant remains: you boarded the aircraft from its left side. This aspect is as fundamental to aircraft design as wings, flaps, and tray tables.

Historically, the design principles of early passenger planes were heavily influenced by the established practices of maritime travel.

Michael Oakley, managing editor of The Aviation Historian, explained to AFAR, “This is one of many aviation practices that trace back to maritime traditions.

Much of the terminology in aviation has its roots in nautical language (such as rudder, cockpit, cabin, bulkhead, knots, etc.), and similarly, many aeronautical procedures are derived from sailing.

Just as ships have a port side—the side closest to the dock—aircraft follow the same convention. It was logical to continue boarding from the port (or left) side.”

In the initial phase of commercial aviation, boarding was somewhat chaotic, primarily relying on mobile staircases for passenger access.

However, as aircraft grew larger and the industry expanded, airports sought more efficient methods to standardize the boarding and disembarking processes.

With the introduction of aerobridges, it became practical for aircraft doors to be positioned consistently, regardless of the airline or type of aircraft arriving.

The architecture of airport terminals has significantly influenced the establishment of this standard practice, particularly with the rise of star-shaped pier finger terminals.

This design features a central hub where travelers can enjoy a drink in the morning before making their way down the various ‘fingers’ to their respective gates. A quick search for images of airports like Chicago’s O’Hare, Amsterdam’s Schiphol, and London’s Gatwick will clearly illustrate this star configuration.

Additionally, the decision to consistently place doors on the left side of aircraft can be attributed to the seating arrangement of pilots. With the pilot positioned on the left side of the cockpit, it made practical sense for them to be closer to the gate, facilitating better judgment of distances when bringing the plane to a stop.