Flight outside of conservative weather conditions

Flight outside of conservative weather conditions

In early May an advanced rated pilot was flying a C rated glider for the first time in strong wind conditions at the North Side POM.  The pilot reported using the speed bar frequently during the flight presumably to keep the glider from being blown over the back of the upper ridge.  After more than an hour of flying, in which the pilot said he felt comfortable with the conditions, the pilot found himself descending in the compression zone behind the upper ridge unable to penetrate to the front of the ridge.  Use of bar at that point just increased the rate of decent.  Fearing descent into the mechanical rotor behind the ridge the pilot turned south, flew to the south behind and away from the ridge and landed in strong surface winds on a small hill near a housing development.

In this case the pilot seems to have turned directly downwind from the point he determined he could not penetrated the headwind head on.  Another strategy is to first crab to the west.  Crabbing is flying crosswind so you are not trying to penetrate the full strength of the wind.  Moving west in this fashion can also increase your ground clearance because the ground’s elevation is dropping away.  If you still cannot penetrate forward of the ridge you will have more clearance fly over the back nearer or over the South Side.  Don’t try to land at the south side, rather land as far south as you possibly can.  Mechanical turbulence can propagate as far as 10 times as far behind the ridge as the ridge is high.   

From the Book of Risk:

As you fly continually assess the wind strength and cloud development.

Know how to get down quickly.  If you see a weather risk you do not wish to accept fly out away from terrain.  Find the greenest most obstruction free landing area you can and land as far away from even the smallest obstacles as possible. 

From the UHGPGA website safety briefings for the North Side:

1. While benching up at the north side fly to the front occasionally to check penetration.
2. If you are above the back ridge and cannot penetrate forward get as high as possible and fly to the west end.  Fly over the south side and land in the fields well south of the south side.

 

Flying in strong winds always increases pilot risk.  The stronger the wind the higher the risk.  There are strategies to mitigate those risks.  At the North Side, those would include staying well out in front of the back ridge.  All of the wind piling up from the bottom of the ridge to the top must combine to make it over the top.  As a result the winds will always be considerably stronger over the top of the ridge.  The depth of this compression zone changes with wind conditions.  

With stronger wind comes stronger turbulence everywhere those stronger winds exist.  

Always weigh your risks against your rewards.  Is moving slowly, or sitting parked in high winds at the edge of being blown back over the back ridge worth the added risk?