I run this on my Android phone and, using Bluestacks, on my Windows 7 Laptop.
https://play.google.com/store/apps/d...aviatool&hl=en
I just had a play and it would be fair to say that it isn't brilliant for South America, but it has some stuff and you can do worse than at-least have a play with it, given that it's free.
Not an app but a website, but you could also take a look at
Great Circle Mapper
G