End of crown line Basket $_{Figure 6-6.}$  Double crown lines forming a 90° or wider angle offer  the greatest inflation stability provided crew walk them directly  upwind on stand-up. $_{Figure 6-5.}$  Crew can often stabilize a rolling envelope by taking a  single crown line 45° off of downwind and walking directly upwind  on stand-up. When selecting a launch site, factors to consider are obstacles  in direction of flight (powerlines, buildings, towers, etc.),  available landing sites, and the launch site surface.  The crown line varies in length. Some pilots let the line  hang straight down; some pilots connect the end of the line  to the basket or burner frame. Other pilots keep the line only  long enough to assist with a windy inflation, or deflation in  a confined area. Usually, there are no knots in the crown  line, but you might find a type of loop attached to it. Some  pilots put knots in their line, or attach flags or other objects.  These may snag in trees and cause problems. Lines tied to  the basket form a huge loop that may snag a tree limb and  should be secured with a light, breakaway tie. The launch site is selected based on surface winds and  winds aloft, in conjunction with the desires of the balloon  pilot. Consideration is given to what type of flight is being  made and to the overall goal of the flight. Upon arriving at  a particular launch site, most pilots release another pibal to  verify the wind direction, and ensure that the forecasts or  earlier readings have not changed significantly.  Ideally, the launch site should be a large, open grassy area.  Obstacles in the flight path are a consideration. As a general  rule, the balloon should be placed as far as possible upwind  of any obstructions to flight (powerlines, trees, buildings,  etc.), using a minimum of 100 feet of clearance for each knot  of wind.  [Figure 6-7] To improve control, some pilots use a double crown line  during very windy conditions. This technique, as shown in  Figure 6-6,  allows for better control of the envelope when  winds may be gusting, but still within reasonable flight limits,  as may be present in an afternoon launch. Many pilots launch  in afternoon winds, knowing that winds generally decrease  significantly as sunset approaches. One advantage of this  technique is that the balloon can be kept stable in fairly gusty  winds, even if held on the ground for an extended period of  time. This may be helpful for the pilot who may be doing  a static (non-flying) tether, or perhaps during an evening  “balloon glow” when winds may remain gusty until well  after sunset.  6-6 Location and Obstacles Launch Site