|MadSci Network: Astronomy|
The term Best On Best (BOB) refers to the Best results under the Best possible conditions, e.g., a perfect landing under perfect weather conditions. It is the opposite of the Worst On Worst (WOW) case, e.g., crashing during a crosswind condition with random gusts. These terms represent two extremes used by engineers to assign a range of possible or probable results over the conditions that will be experienced.
In terms of the flight simulator, think of it as the range of scores that can be attained over the range of conditions in the missions that you will experience. It does not include conditions or results that are set to be out of bounds, e.g., landing the shuttle during a hurricane.
Try the links in the MadSci Library for more information on Astronomy.