Cloudee, I'm not entirely sure, but I think that Flight Aware merely takes the distance between the 2 points and divides it by the filed flight speed, doesn't quite work for a Skydiving Aircraft which only moves a short distance over the ground between 2 points whilst climbing.
Ie, I might only be planning to fly between 2 points which are 17 minutes apart at normal cruise speed but if I'm going to climb from SL to 10,000ft then descend back down again that will obviously take longer than 17minutes in a typical SE Cessna.