It's a yearly "get-together" actually. Bluegrass Airlines hosts it. They setup a timing flight, to get a baseline time for each pilot and his airplane. Only 1930's to 1950's aircraft are allowed (no jets or turboprops). We fly 10 different legs and each leg has a "target time" based on our initial test flight. Winners are figured on how closely you stuck to your target times. Weather is different for each flight, no GPS, only dead reckoning, NDB/ADF. The flights aren't extremely long, so if you do any pre-planning at all and even know the general direction of flight you can probably find your airport just based on your average speed, distance to the airport and winds, lol.
It's always just a lot of fun and I get to fly in a part of the world I don't normally fly in.