(CNN) — If you've ever played with the in-flight route maps on board a plane or browsed the destinations on an airline's website, it all looks pretty simple.
To get from A to B, you simply rise to 30,000 feet and take the most direct path through clear, empty air, right?
The reality, of course, is a little more complicated.
Route planning is dictated by a range of factors including weather, geopolitics, how much a country charges for aircraft to fly over its territory, and even runway length.
Even those back-of-seat maps don't give you the full story: They'd need to be updated in real time just to keep up with variable wind speeds and political bickering.
An in-seat screen on an Air India flight.
Nicolas Economou/NurPhotoGetty Images
100 years of route maps
Official airline route maps first appeared in the 1920s, in the early days of commercial aviation. The focus was on their use as a marketing tool, rather than geographic accuracy.
Flying was significantly more expensive during the first decades of passenger service. In the early 1950s, the average domestic US round trip cost at least 5% of the average annual income (make that close to $2,000 in today's world).
It was only with the passage of the Airline Deregulation Act of 1978 that US airfares stopped being set by the federal government, which paved the way for greater competition and much lower prices.
Thus, in order to appeal to upper income brackets, early route maps would be fancifully decorated, with the emphasis on cultivating wanderlust by introducing new and exotic locales.
Although transcontinental railroads and mass transit system maps had been in use since the late 1800s, they were more functional than vivid, whereas airlines like Pan Am and KLM used multiple colors and themes to show off their ever-expanding presence.
Without showing scales or legends, they would merely connect airports, with exaggerated straight lines being drawn between the airline's home airports, better known as hubs, and its route network.
The point of the maps -- nicknamed aerial road maps by American Airlines in the 1930s -- was to make the graphics easy to understand, captivate the audience, serve as fun souvenirs, and even help passengers keep track of the newest destinations.
"Pan American" physical map with red lines tracing the airline's international routes, cartography by John Brown for Pan Am, 1968.
Potter and Potter Auctions/Gado/Archive Photos/Getty Images
The jet age
Though the world's first jet plane, the Heinkel He 178, took flight in 1939, it was years before the first commercial jet flew paying passengers on a scheduled service.
On May 2, 1952, the British Overseas Aircraft Corporation (BOAC), using the 44-seat De Havilland Comet 1A, took flight between London and Johannesburg, inspiring aircraft manufacturers in Europe, North America, and the former Soviet Union to develop their own prototypes.
As newer aircraft were able to fly longer distances at higher altitudes and with less of a need to refuel at intermediate stops, so too did airlines continue to grow their reach around the world, expanding throughout newly independent countries in Africa and Asia, in addition to growing tourism and business hotspots in the traditional aviation markets of Europe and North America.
The Heinkel He 179 was the world's first jet plane and was used by the Luftwaffe during World War II.
Apic/Hulton Archive/Getty Images
However,there's more to connecting two points than simply having the appropriate aircraft. And sometimes it's politically expedient for airlines to steer clear of explaining why their route maps might look a certain way.
Two particular examples, El Al of Israel, and China Airlines of Taiwan, have had to avoid the airspace of certain neighbors for decades.
In 1948, the same year that Israel was founded, the national air carrier El Al was formed as a source of pride and hope for the fledgling state.
Though the initial commercial routes, to Rome and Paris, were comparatively simple to navigate, once Israel established diplomatic relations with South Africa, Thailand, and India, it would be an understatement to say that setting up routes to Johannesburg, Bangkok, and Beijing was merely a matter of selling tickets.
When the British administration in Sudan began giving way to local Arab government in the mid-1950s, according to Maurice Wickstead of theaviationhistorian.com, "This necessitated a major diversion avoiding hostile nations bordering the Red Sea."
Rerouting via Turkey, Iran, Oman, Somalia and Kenya "added around 2,400 miles to the straight-line distance and five hours flying time," says Wickstead. "This situation was not rectified until Israel gained control over the Sinai Peninsula" and direct flights over Ethiopia could be made.
Things also improved in September 2020 when Saudi Arabia started allowing Israeli aircraft to fly over its territory, not only for its new routes to the United Arab Emirates, but also occasionally for flights from East Asia.
As Ian Petchenik of FlightRadar24 notes, "the most geopolitically consequential routing changes in the Middle East in 2020 also carry the most practical consequences for airlines, saving time and fuel."
May 2, 1952: Passengers bound for Johannesburg board a British Overseas Airways Corporation (BOAC) De Havilland Comet jet airliner at London Airport on the inaugural flight of the first regular jet service in the world.
Monty Fresco/Picture Post/Getty Images
Meanwhile, Taiwanese airlines have their own unique issues when plotting their daily flight routes. As China's economy has exponentially grown since the late 1970s, Beijing feels more empowered to show off its increasingly high-tech military capabilities, particularly in Fujian province, directly across the Strait of Taiwan.
Moreover, Taiwan -- also known as the Republic of China -- was expelled from the United Nations in 1971, at the same time the China -- or, the People's Republic of China - took its place.
According to the Asian Maritime Transparency Initiative, "Taiwan's exclusion from the international body means it has no formal avenue for registering complaints against China's aviation actions."
Naturally, China has separately been more open to discussions with Taiwan increasing flights between the two when Taiwanese leadership is pro-Beijing.
Still, in spite of regional aggression, airlines have been flying between Taiwan and China on a charter basis since 2005, with scheduled flights happening since 2008. (Previously, in order to get between mainland China and Taiwan, one would have to transit another airport, likely Hong Kong or Macao).
However, where things get a bit trickier is when China Airlines and Eva Air, both based in Taiwan, depart for Europe.
Although official documentation is difficult to come by, as a rule, Taiwanese airlines are unable to use Chinese airspace.
A possible reason is that the Chinese military controls most of mainland airspace, not to mention Chinese airlines have had massive domestic growth in the past twenty years, further crowding up the skies.
Yet, Taiwanese flights returning from Europe have recently been allowed to overfly southern Chinese airspace; in fact, the three European carriers to fly to Taipei: Turkish Airlines, KLM, and Air France, are also only able to use southern Chinese airspace, regardless of whether they are flying to/from Europe.
In conclusion, it's easy enough to visit an airline's website, scope out the route map, and dream up your next vacation.
Yet until now, you may never have thought about the process through which daily flights around the world must carefully tread: to name just a few, national borders, storms, war zones, pandemics, and temporary airspace restrictions, such as for visits by world leaders, and major sporting championships.