The Boeing 747 will go down in history as one of the most iconic airliners of all time. It has been in the skies for more than 50 years, with production ending this year. Its most notable feature is its upper deck, which provides an exclusive space for a select few passengers. But why can't passengers board this area directly?

Passengers have to take the stairs

Readers who have been lucky enough to travel on the upper deck of the Boeing 747 will know how the boarding routine pans out. Having entered the aircraft on its lower deck, such passengers have the privilege of climbing the stairs to that forbidden realm atop the main cabin. This is an enthralling experience, but could it be avoided with direct boarding, with a jetbridge that connects to the top floor?

There is a door on the upper deck, so wouldn't it be feasible to board passengers directly, saving them the trip upstairs? In practice, this would not work for multiple reasons. First of all, the deck's capacity is minimal. So, the infrastructure required for another jetbridge wouldn't be worth it for just a few passengers.

Crucially, the door on the upper deck is used primarily as an emergency exit. As users of Airliners.net discussed, the presence of a slide in the door's mechanism means that this safety feature would block the jetbridge. Additionally, the door in question opens upwards, which further complicates matters.

A380 does allow upper deck boarding

However, the Airbus A380 contrasts with the 747 in this regard. A key difference between the A380 and the 747 is the fact that the former has a full upper deck. As such, this means that investing in the infrastructure to have jetbridges serving the upper deck is easier to justify, as far more passengers use this area of the plane. As seen below, the jetbridges offer step-free access to the upper deck.

Of course, contingencies must be in place for the rare occurrence when an upper deck jetbridge might not be available. In this instance, passengers simply climb the stairs, but what about wheelchair users? For this purpose, the A380 features an internal stairlift. We took a closer look at this equipment in an article last year.

Upper deck adventures

While the upper deck of the 747 can't be boarded, there have been several nuances related to it throughout the decades. The spiral staircase was a phenomenon in the jumbo's early years, representing a luxury era in air travel. Moreover, Delta Air Lines promoted the sale of a 'flying penthouse' on the top deck.

KLM was a pioneer with its stretched upper deck on the 747-200. This feature would soon become a standard with the type.

An increasingly rare aircraft type

Since 1968, Boeing has produced 1,574 examples of what must be one of the most recognizable commercial aircraft of all time. While the 747's majesty is revered worldwide, demand for such large quadjets has sunk in recent years, and production has come to an end.

The final 747 to be produced was handed over in January this year. Atlas Air was the airline to take the last-ever delivery of the legend.

According to data from ch-aviation.com, there are presently just over 350 active 747s left across the globe, with this figure comprising all of the type's variants. The -400 is the most active model of them all.

However, with the overall program now complete, and existing examples only getting older, this figure will likely fall. Nonetheless, the new 747-8 series will mean that the jumbo jet will remain the 'Queen of the skies' for a little while longer yet.

What do you make of the Boeing 747? Have you ever flown on the upper deck of one? Let us know your thoughts and experiences in the comment section.

Source: Airliners.net; ch-aviation.com