For inquisitive types it can be a real voyage of discovery to learn the route planes take to get from one place to another.
You might think the ‘as the crow flies’ theory would apply to flight paths, but this is not always the case. By using a flight radar, you can see how a plane may need to take a more round about route to avoid certain obstacles, both physical and otherwise.
The most obvious reason why an aircraft would need to alter its course in the process of getting from A to B is if the landscape prevents it; for example, a mountain range may prompt a pilot to seek a different route.
At the same time, it may sometimes be more sensible to cross a mountainous area in favour of crossing a section of airspace that is known for harbouring difficult weather. A bit of rough turbulence may be annoying for a passenger, but it can be worrying for a pilot if their aircraft is wobbling around too much.
Another cause for a plane to take an unusual course is if legal restrictions apply to a specific piece of airspace. This can happen for a number of reasons. It may be that one plane is not allowed in another nation’s airspace because of diplomatic problems, or there may be more localised issues – such as a military zone in which no other vehicles are allowed.
Not all limitations are so negative though – often flight paths are selected so as to respect the peace of residents living in neighbourhoods around airports. So you might see a plane approaching an airport from one side and then taking a peculiar final route to get to the facility. Alternatively, the pilot may just be lining himself up for a smoother landing.
Either way, it is the best interests of either passengers or people on the ground that dictate flight paths – however unusual they may seem.