Flight outside of conservative weather parameters.

Flight outside of conservative weather parameters.

In late winter, a speed wing pilot crash landed on the North Side of the Point of the Mountain.  By his own report the winds were switching at the time of launch and landing.  The pilot forward launched in a Southwest wind running down the road at the top of the back ridge.  The pilot soon encountered significant lift that did not make sense in his mind so he turned to the west to leave the lift.  At this time the lower wind sock was showing wind from the north northeast. Setting up for landing the pilot noticed his ground speed was excessive.  And he planed to skid the fast landing out on his butt.  At 20 feet AGL the pilot felt himself drop suddenly to the ground causing some injury.  

The pilots description of switching light winds combined with thermic winds indicates complicated wind gradients.  When a glider transitions from one air parcel to parcel moving slower or in a significantly different direction the glider’s air speed can be affected.  If the glider’s air speed is lowered it will immediately dive to regain its airspeed.  When this happens close to ground it feels as though you drop to the ground like a rock.   Lesson learned here is that even with light winds, switching conditions close to the ground increases your risk level.

Changing weather conditions increase our risk because it is possible that conditions can switch form safe to unsafe or the transition can be momentarily unsafe.  XC flying by its nature is flying in changing conditions.  When we are high this is less of a problem than when we are low.  Speed flying and ridge soaring cause us to spend a much greater amount of time close to the ground and therefore it is wise to be even more conservative in the weather we choose to fly in.  Just waiting for conditions to stabilize after a change can decrease our risk.

From the Book of Risk:

Begin your day early studying weather forecasts.  Learn to read them and what they mean.  Watch the wind, clouds and birds as you travel to and set up on launch.  As you fly continually assess the wind strength and cloud development.