1. Teaching Soaring Weather
Soaring Safety Foundation
FIRC
Rich Carlson

2. Basic Principles Obtain the basic weather data
Know how the atmosphere works
Use some simple calculations to see if soaring is possible
Graphs and pictures improve student understanding
Weather analysis continues throughout the flight

3. Obtaining Weather Data
Look Outside
Local sounding
Flight Service Station (1-800-WXBrief)
National Weather Service
Duat
3rd party service provider
Internet ( and Web)

4. Atmospheric Assumptions
Pressure lapse rate 1” hg/1000 ft
Dry adiabatic lapse rate 5.4o (3c)/1000 ft
Wet adiabatic lapse rate less than dry
Dew point decreases 1o / 1000 ft

5. Soaring Calculations Thermal Index (TI) Cloud base
measured - adiabatic (minus is better)
Cloud base
(max surface - dewpoint)/4 (in 1000’s of ft)

6. Obtaining a Weather Briefing
FSS call (WXBrief)
Identify yourself as a glider pilot
Give Aircraft ‘N’ number
Say type of flight and location
Ask for standard briefing
Ask for surface reports
Ask for winds aloft forecast
Ask for Soaring forecast
Ask for other pertinent data (Notams, TFR’s)

7. Pseudo-Adiabatic plot
Src: Soaring Flight Manual

8. Typical FSS Soaring Forecast
T.I. at 5000 ft -5
T.I. at 10,000 ft +2
Height of
Top of Lift
Max Expected Temp 89
Morning Low* 50

9. Step 1, draw the adiabatic line

10. Step 2, add the T.I. dots

11. Step 3 Draw the sounding

12. Internet Sources Kevin Ford - http://www.soarforecast.com
NOAA-FSL, Forecast Systems Laboratory -
Aviation Digital Data Service -
Dr Jack BLIPMAP -

13. Kevin Ford Plots
=== Interpolations (temps in deg. F, altitudes in feet MSL) ===
MSL *TI* trig VirT 1.2 degrees/division ("`": Dry Adiabatic)
| -9.8 ` :
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| `:
| :`
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| : `

14. NOAA Forecast Plot

15. ADDS METAR/TAF Data

16. Dr Jack BLIPMAP

17. Local factors
Terrain features
Ridges
Mountains
Rivers
Lakes
Towns

18. Local factors Ridge conditions Calculations Predictions Ridges
90O +/- 30O to ridge line
kts
Ridges
Lift extends 2 – 3 times the ridge height
Ridge length should be several miles

19. Ridge Lift Zones

20. Local factors Wave conditions Calculations Predictions Wind at peak
15 – 20 kts
Wind 2000 m above peak
Same direction
20 – 25 kts higher

21. Mountain Wave System

22. Transition pilot wave sketch
4/14/2018

23. Some rotor research in progress
4/14/2018

24. Some rotor research in progress
4/14/2018

28. Thermal Predictors/Indicators
Negative Thermal Index values at alt.
Forecast plots
Clouds
Birds/Gliders circling
Dirt, crops, houses, animals rising before your eyes

29. Go/No-Go Decision Making
Use realistic scenarios
Storms forecast for later in the day/evening
Effect of strong x-wind
Local vs X-C flight
Pilot experience level

30. Continuing Weather Analysis
Obtaining enroute weather data
Flight Watch (122.0 Mhz)
Airport automated weather services
Obtaining end-of-flight weather data
Wind direction for landing
Current Altimeter setting

31. En Route Flight Advisory Service (Flight Watch)
AIM section 7-1-5
Real-time weather advisories
National coverage above 5000 ft on 122.0
Available 6:00 am to 10:00 pm
State ARTCC facility, N number, & nearest VOR name

32. Types of Fronts Cold Warm Occluded Good soaring conditions
squall lines miles ahead
Warm
temperature inversion
broad cloud system precedes front
Occluded
both warm & cold cloud patterns

33. Src: Aviation Weather AC 00-6A
Cold Front
Src: Aviation Weather AC 00-6A

34. Src: Aviation Weather AC 00-6A
Warm Front
Src: Aviation Weather AC 00-6A

35. Src: Aviation Weather AC 00-6A
Cold-Occlusion Front
Src: Aviation Weather AC 00-6A

36. Src: Aviation Weather AC 00-6A
Warm-Occlusion Front
Src: Aviation Weather AC 00-6A

37. Seasonal Weather Operations
Density Altitude
Thunderstorms
Frost, Snow Ice
Temperature extremes
Wind shear
Microbursts

38. Determining When to Land
What effect does the wind have on landing?

40. Effect of 20 Kt wind Time on Downwind: More, Less, no Change?
Altitude loss: More, Less, no Change? 27 9
20 Kts

41. Effect of 20 Kt wind Time on base: More, Less, no Change?
Altitude loss: More, Less, no Change? 27 9
20 Kts

42. Effect of 20 Kt wind Time on Final: More, Less, no Change?
Altitude loss: More, Less, no Change? 27 9
20 Kts

43. Effect of 20 Kt wind Which path is your student likely to fly?
Which path do you want them to fly? 27 9 4
20 Kts 3 1 2

44. Final Approach (No wind)
ft/m decent rate
12:1 glide slope
24 seconds
200
2400

45. Final Approach (20 Kt Head Wind)
ft/m decent rate
8:1 glide slope
24 seconds
200
1600
2400

46. Final Approach (20 kt wind shear)
ft/m decent rate
Maintain constant speed during approach
How much time remains?
200
20 kts
With 20 kt shear, are you likely to overshoot your intended aim point (into area Y) or undershoot (into area X)
Said another way, what actions do you need to take to reach your intended touchdown point
1) close the spoilers to extend (undershooting)
2) open the spoilers to sink faster (overshooting)
Another variation, what will the aim spot do?
1) move up on the canopy (undershooting)
2) move down on the canopy (overshooting)
0 kts X Y
1600
2400

47. 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)

48. Glide Distance
L/D
Height
distance 8
100
800 12 67 20 40 27 30

50. How much Altitude does it take to regain original airspeed?

51. Transition through Wind Shear Line
Speed
(kts)
Time
(s)
Alt Remaining
(ft)
Distance 60
100
800 50 1 89
867 40 2 70
934
Is this a reasonable amount of time for the student/pilot to wait before responding? What would your reaction time be?

52. Final Approach (20 Kt Wind Shear)
2 seconds for the glider to stabilize at the new sink rate
AOA increases from 0.5o to 5.0o
200
20 kts
0 kts
934
1600
2400

53. Distance & Altitude during recovery phase
Speed
(kts)
Time
(s)
Alt Remaining
(ft)
Distance 40 70
934 47 1 56
1012 53 2 31
1110 60 3 -5
1230
Gravity is the only motive force, so nose is lowered 20 deg below the horizon to accelerate the glider 20 kts in 3 seconds.
In 5 seconds (2 sec 60 -> 40 and 3 sec 40 -> 60) and we are 5 ft below the runway surface. What happened to the other 7 seconds?
100 ft 500 fpm is 12 seconds from landing. 12 – 5 = 7 We not only lost altitude, we lost time.

55. Final Approach (20 Kt Wind Shear)
3 seconds to accelerate back to 60 Kts
Glider nose is 20o below the horizon
200
20 kts
0 kts
1230
1600
2400

56. Final Approach (Likely outcome in 3 cases?)
No Wind
Constant headwind
20 Kt Wind Shear
200
1230
1600
2400

57. 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)

58. Shear Encounters When can this happen? Landing in gusty conditions
Landing area shielded by obstructions
During good thermal conditions
You do not need strong winds for this to occur. Suppose a thermal breaks loose ¼ mile in front of you? Wind will flow into the thermal, causing a shear as the headwind turns into a tailwind on short final.

59. 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

60. 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!

61. Effects on Landing Steady wind requires more energy
800 feet closer or 100 ft higher for 20 kt wind
Changing wind requires more energy
Sink requires more energy
Ask yourself “Are you more likely to wind up getting low or high on final?”