Glider Flight Planning
When you fly cross country in an airplane, you have to make sure you get to your destination with a sufficient fuel reserve. In a glider, you have to plan to arrive at your destination with enough ALTITUDE reserve. How do we fill our altitude tank? Lift.
A glider flight plan is three dimensional. Because it is relatively difficult to predict how much lift you'll get at each point along the flight, it is important to identify many potential landing spots along the way, as well as minimum safe altitudes at the half-way points between each of the landing spots. If you're not at your minimum safe altitude at the halfway point, you have to return to the previous landing spot. Some landing spots are better than others. For example, a paved private airport would be better than a military airfield. A dry lake-bed would be better than a road with telephone poles. Some potential landing spots might not be used in your flight plan, but you would know that they lie beneath your route in case of an emergency.
I'm just starting my glider flying career, so I'm taking some extra conservative measures. The glider I'm training in, the ASK-21, has a glide ration of 37:1. However, for planning purposes, I'm using only 20:1. Also, I'm building in a 1,500' safety margin at each potential landing spot, so that I have sufficient altitude to maneuver into a normal traffic pattern. See the image for an example flight plan from Crystal Airport to Inyokern.
The neat thing about these plans is that they can pretty much be used on any day in the future. Of course you would always obtain a comprehensive weather briefing to evaluate the weather for soaring conditions and safety of flight considerations, but if you make those minimum safe altitudes, this flight could be made anytime.
I'm just finishing up my glider rating now. I love the school I'm training at. Check out www.soaringacademy.org. Chris, Julie, Ron, George and the rest of the crew are fantastic.