Soaring Weather

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Teaching Soaring Weather
Soaring Safety Foundation FIRC Rich Carlson
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Determining When to Land

• What effect does the wind have on landing?

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(No Transcript)
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Effect of 20 Kt wind
Time on Downwind More, Less, no Change? Altitude
loss More, Less, no Change?
20 Kts
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Effect of 20 Kt wind
Time on base More, Less, no Change? Altitude
loss More, Less, no Change?
20 Kts
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Effect of 20 Kt wind
Time on Final More, Less, no Change? Altitude
loss More, Less, no Change?
20 Kts
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Effect of 20 Kt wind
Which path is your student likely to fly? Which
path do you want them to fly?
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20 Kts
3
1
2
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Final Approach(No wind)
60 kts _at_ 500 ft/m decent rate 121 glide slope 24
seconds
200
2400
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Final Approach(20 Kt Head Wind)
60 kts _at_ 500 ft/m decent rate 81 glide slope 24
seconds
200
800
2400
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Final Approach(20 kt wind shear)
60 kts _at_ 500 ft/m decent rate Maintain constant
speed during approach How much time remains?
200
20 kts
0 kts
X
Y
800
2400
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Decision Time

• With a 20 kt shear, are you likely to
• overshoot (into area Y)
• undershoot (into area X)
• Said another way, what actions do you need to
  take to reach your intended touchdown point
• close the spoilers to extend (undershooting)
• open the spoilers to sink faster (overshooting)
• Another variation, what will the aim spot do?
• move up on the canopy (undershooting)
• move down on the canopy (overshooting)

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How much Altitude does it take to regain original
airspeed?
?
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Preliminary Analytical Results

• No Wind
• Distance is X
• Steady 20 Kt head wind
• Distance is X 0.67 (33 shorter)
• Wind Gradient Case
• Distance is X 0.47 (53 shorter)

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Shear Encounters

• When can this happen?
• Landing in gusty conditions
• Landing area shielded by obstructions
• During good thermal conditions

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Recommendations

• Plan for this loss of energy
• Pick an approach speed that will allow for some
  loss
• Move base leg closer to runway edge
• Be higher turning Final
• Be prepared to close the spoilers
• Be prepared to pitch forward to maintain/recover
  airspeed

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Conclusions

• Shear line causes loss of Total Energy
• Large Pitch change required to rapidly recover
  lost energy
• Large amount of Time lost while total energy
  changes
• Immediate action is required to reach original
  touchdown point!