Mission Aircrew Course Weather (APR 2010)

1. Mission Aircrew CourseWeather(APR 2010)

2. Aircrew Tasks • P-2008 DISCUSS THE DANGERS OF ICING (O) • P-2009 DISCUSS THE DANGERS OF REDUCED VISIBILITY CONDITIONS (O) • P-2010 DISCUSS THE DANGERS OF WIND AND THUNDERSTORMS (O) • P-2023 DISCUSS HOW REDUCED VISIBILITY AND TURBULENCE EFFECT SEARCH OPERATIONS (S)

3. Objectives • Discuss how convection currents affect aircraft glide path. • Discuss wind patterns around high- and low-pressure areas. • Define “freezing level” and “lapse rate” • Discuss airframe icing and its affect on aircraft performance. • Discuss carburetor icing and its affect on aircraft performance.

4. Objectives (con’t) • Discuss the characteristics of cold, unstable air masses and warm, stable air masses. • Concerning reduced visibility conditions, state the minimums for: • VFR visibility • Cloud bases when they cover one-half the sky • How far aircraft must remain below cloud cover • Discuss the dangers of windshear. • Describe the ‘stages’ of a typical thunderstorm and discuss the dangers of flying too close.

5. Weather • The most important aspect of weather is its impact on flight conditions • Safety is paramount • Navigation — Visual verses Instruments • Effects on Search • Prevailing visibility • Search visibility • Search patterns and altitudes • Information — National Weather Service, Flight Service Stations, Flight Watch, PIREP’s

6. Flight precautions • Each member of the aircrew must be vigilant during all phases of flight • Assign each an area to watch • Characterize visibility in the search area to establish the proper scanning range • May be different than assumed • Visibility conditions or turbulence may increase fatigue

7. Weather — Circulation

8. Weather — Circulation • The earth rotates • Air moving north is pulled toward the east • This builds a high pressure belt about 30 degrees latitude • The northerly air flow cools and starts southward • These large circulations are responsible for mixing the air and most weather

9. Upward Convection Currents • Terrain which heats up creates updrafts • Updrafts tend to keep you from descending • Normally where there are updrafts there are also downdrafts EFFECT OF CONVECTION CURRENTS NORMAL GLIDE PATH ROCKY TERRAIN PLOUGHED GROUND PAVED ROAD

10. GLIDE PATH DUE TO CONVECTION CURRENTS NORMAL GLIDE PATH RIVER GROWING FIELDS LANDING FIELD Downward Convection Currents • Terrain which remains cool creates downdrafts • Downdrafts cause you to descend

11. Turbulence • Planning flight around high terrain requires special care • Wind currents on the downwind side can be very strong • Ridges and peaks should be cleared by at least 2000 feet Flight Path 2000 ft. Wind

12. H Circulation Around a High Air Sinks Moves Clockwise

13. Circulation Around a Low L Air Rises Moves Counter Clockwise

15. LAPSE RATE • As altitude increases the temperature decreases at a fairly uniform rate of 3.6 degrees F per 1000 (2.0 degrees C per 1000) feet; this is known as lapse rate • Use this on hot days to determine how high you should climb to get to a comfortable temperature • At some altitude the air temperature reaches the freezing temperature of water; the freezing level

16. Rime ice is rougher Glaze ice is clearer Icing • Frost • Snow • Icing • Airframe (lift & weight) • Carburetor Drag Lift Increases Decreases W eight Thrust Increases Decreases

18. The wing of a NASA Twin Otter after landing. This looks to be clear icing or perhaps mixed. Notice the runback well past the leading edge and on the underside of the wing.

19. The rectangular device on the windshield is the "hot plate", a plate of electrically heated glass which is mounted just ahead of the plastic windshield. When ice formation is especially bad, the only view forward is through the upper two- thirds of the plate, and the area around it becomes crusted with frozen runoff from the heated area.

21. Carburetor Icing • Moisture in the air can condense, then freeze, blocking further flow of air and fuel to the engine. • Airplanes most vulnerable when operated in high humidity OR visible moisture with temperatures between 45F and 85F. • Most likely to form at low power settings such as in descents and approaches to landings. • Fuel injected engines are not vulnerable to carburetor icing.

22. Causes of Frontal Activity COLD POLAR AIR DRY AIR TROPICAL MOIST AIR

23. WARM AIR Cirrus Cirrostratus Altostratus COLD AIR Nimbostratus St Louis Indianapolis Columbus Pittsburgh Warm Front dust/polutants

24. WARM AIR Cumulonimbus COLD AIR St Louis Indianapolis Columbus Pittsburgh Cold Front

25. Cirrus Cumulonimbus WARM AIR Cirrostratus Altostratus Nimbostratus COLD AIR COLD AIR St Louis Indianapolis Columbus Pittsburgh Occluded Front

26. Clouds Altocumulus

27. Lenticular

28. Lenticular

29. Towering Cumulus

30. Mushroom Cloud

31. Reduced Visibility • Under almost all circumstances, VFR daytime flight requires: • At least three miles visibility • When clouds cover more than one-half the sky, cloud bases must be no lower than 1,000 ft. AGL • Search aircraft must usually remain at least 500 ft. below the cloud deck

32. Reduced Visibility • Fog • Haze • Snow • White out • Blowing dust • Affected by sun angle and direction • Aircrew must increase vigilance during these conditions

33. Wind Shear • Thunderstorms • Fronts - wind shear may advance as far as 15 nm • Air flow around obstacles Windward

34. Wind Shear • Two potentially hazardous situations, dangerous mainly during landing: • Tailwind turns calm or to a headwind • Headwind turns calm or to a tailwind • Critical conditions for potential low-level wind shear: • Cold Front: • After front passes • If moving 30kts or more, may exist below 5000 ft for up to 3 hours • Warm front: • Before front passes • May exist below 5000 ft. for up to 6 hours • Danger passes once front passes airport • Pilot must adjust quickly

35. Weather — Thunderstorms Cumulus Stage Mature Stage Dissipating Stage

36. Lightning In Cloud (IC)

37. Cloud to Cloud (CC)

38. Flight Planning WX SourcesTelephone National Weather Service 1-800 –WX Brief (1-800-992-7433) Standard Briefing • METARS (updated as significant change has occurred) • Terminal Area Forecast (i.e. IND) • Good for 12 hours • 3 x per day • Area Forecast (entire state or area you designate) • Every 12 hours • Route of Flight

39. Winds Aloft • All altitudes • Notams • Current Airmets • Convective Sigmets • Cloud Tops (reported) • Pilot Reports (PIREPS) • High/Low Pressure Areas • Fronts

40. Flight Planning WX Sources Computer • AOPA.org • Weather • Satellite Images • Radar Imagery • Surface Wx Imagery • Upper Air Imagery • Textural Wx.

41. Flight Planning WX Sources Computer • Weatherunderground.com • Temperature • Heat Index • Wind Chill • Radar • Dewpoint • Visibility

42. Flight Planning WX Sources Computer • Intellicast.com • Radar • Severe Weather • Satellite • Surface Analysis • Hurricane Watch • More Spam

43. Flight Planning WX Sources Computer • NOAA’s National Weather Center (adds.aviationweather.noaa.gov) • Turbulence • Convection • Winds/Temps • Prog Charts • Metars • Tafs • Pireps

45. Plain Language Interpretation of METAR

46. JOT Time 1240Z C-172 at Fl Level 2500. Reported sky cover was overcast from 8000-10000 ft. Occasional light chop. Scattered Virga Observed.

47. JOT reported at the same time 1245Z showed surface weather winds from 190 at 4knots, visibility was 10sm and CLEAR! Temperature was 23C and dewpoint 19C.

48. Radio Services • Flight Service Station (FSS) • Flight Watch (122.0) • Automatic Terminal Information Service(ATIS) • Transcribed weather broadcasts (TWEB) • Scheduled weather broadcasts • Fifteen minutes after the hour • Alerts, hourly weather, Advisory, Pilot Reports, Radar • Pilot Weather Reports (PIREP)

50. Questions?