Following the paper work for flying routes and networks, there are few places not accessible to passengers plane. This particular areas have strict airspace restrictions that prohibit the entry of commercial aircraft, either due to factors such as political, religious, historical and environmental reasons.
Areas of religious significance
One of the restricted areas is Religious places, like the Islamic holy city of Mecca in Saudi Arabia . The Religious customs prohibits airplanes from entering Mecca and, particularly, flying over the Holy Kaaba. Passenger aircraft are not allowed to travel over Mecca as a mark of respect to this holy site.
Non-Muslims are not permitted to travel to Mecca, as it is a sacred place for the Islamic faith, and the center of the Hajj pilgrimage. This rule of keeping Mecca for the Muslim population is so strictly upheld that non-Muslims in Mecca can face a fine and deportation. This would include non-Muslims who fly over Mecca, hence commercial aircraft are prohibited.
Areas of environmental significance
Aviation has caused quite a stir in Peru in recent years. The building of Chinchero Airport, which remains under construction, is highly opposed by activists and historians. Due to the area’s fragile ecology and the significance of the Inca ruins at Machu Picchu, an airport is the last thing that this region needs.
As it is, aircraft are not allowed to fly over Machu Picchu, which is a site of extreme cultural significance. The area also has a delicate balance of nature, which is best left untouched. The danger with flying commercial aircraft over the region is that, should any aircraft crash or have an emergency landing in the area, it would undoubtedly damage the precious ecosystem. Furthermore, the side-effects of increased pollution in this region could prove destructive for natural habitats.
Areas of historical significance
Much like flying over Machu Picchu, the reason that passenger aircraft steer clear of the Parthenon in Athens is to protect this historical wonder. This impressive structure on the Athenian Acropolis was a temple dedicated to the Ancient Greek goddess Athena.
While aircraft are permitted to fly over this monument, they must give it a wide berth. Specifically, no aircraft are allowed to fly below 5,000 feet when above the Parthenon.
Areas of political significance
London‘s Downing Street is one of the most significant streets in the UK. Home to the serving British Prime Minister, access to this gated location requires special permissions.
As a measure of protecting the country’s political elite, aircraft are not allowed to fly directly over this street. In the same vein, a similar restriction also applies above the Houses of Parliament. The Queen’s residences at Buckingham Palace and Windsor Castle also feature no-fly zones directly over these luxurious structures.
Protecting customer safety
There are also numerous places around the world where restrictions have been issued to increase visitor safety. After 9/11, certain US tourist hotspots felt a need to increase their security. As such, commercial aircraft are not allowed to fly over some of them even today.
In 2003, a temporary ban on flying over Disney parks was made permanent. It dictates that no aircraft can fly below 3,000 feet over Walt Disney World in Florida, or Disneyland in California. In any case, this restriction is not such a concern for commercial aircraft, as there would little reason to fly so low in these areas anyway.
Similar bans to protect people from future aircraft-based terrorist attacks have also been implemented for other visitor hotspots. These include the airspace above stadiums in the US which seat more than 30,000 spectators. Wikipedia lists 182 examples of stadiums with such capacities, which host such sports as football, baseball, and American football (at both college and professional level).