My Dictonary says scavenger hunt or paper chase

Recently came to that idea when playing morrowind.

Imagine some sort of mission like "the hunt for the holy grail"
(just for example didn´t find any better )

You start by getting directed to a specific airport or some
other place where you find information for the next flight
Like "find the first part of the ancient map at the second
airport hangar at XY airport somewhere"
than you have to fly there to get the next information
that will guide you to your next location and so on.

I could imagine a wide range of riddles like objects that
are only visible at night or at a specific date..
or that you have to search a specified region for some
hotspot . Different flight ranges where you sometimes have to use big machines and sometimes small ones.
Places you need to reach in a specific time or the information gets lost.. and so on.

I know for many users this would be to much game style
But I think it would be great fun...

It's payware, but the new FS Flight Ventures from Abacus has a couple of missions that are exactly the scavenger hunt like you describe, plus several other missions to test your abilities.  I got it for Christmas, and have found it to be a wonderful add-on.