EXAMPLE.
Alert provided by an AFSS/FSS:
(aircraft identification) EXTREME precipitation two zero
miles west of Atlanta V.O.R, two five miles wide, moving
east at two zero knots, tops flight level three niner zero.
28. Thunderstorm Flying
28.1 Above all, remember this: never regard any thunderstorm lightly, even when radar observers report the echoes are of light intensity. Avoiding thunderstorms is the best policy. Following are some Do’s and Don’ts of thunderstorm avoidance:
28.1.1 Don’t land or takeoff in the face of an approaching thunderstorm. A sudden gust front of low.level turbulence could cause loss of control.
28.1.2 Don’t attempt to fly under a thunderstorm even if you can see through to the other side. Turbulence and wind shear under the storm could be disastrous.
28.1.3 Don’t fly without airborne radar into a cloud mass containing scattered embedded thunderstorms. Scattered thunderstorms not embedded usually can be visually circumnavigated.
28.1.4 Don’t trust the visual appearance to be a reliable indicator of the turbulence inside a thunderstorm.
28.1.5 Do avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus.
28.1.6 Do clear the top of a known or suspected severe thunderstorm by at least 1,000 feet altitude for each 10 knots of wind speed at the cloud top. However, the altitude capability of most aircraft make it unlikely that the aircraft will be able to clear the storm top.
28.1.7 Do circumnavigate the entire area if the area has 6/10 thunderstorm coverage.
28.1.8 Do remember that vivid and frequent lightning indicates the probability of a severe thunderstorm.
28.1.9 Do regard as extremely hazardous any thunderstorm that tops 35,000 feet or higher whether the top is visually sighted or determined by radar.
28.2 If you cannot avoid penetrating a thunderstorm, before entering the storm, you should do the following:
28.2.1 Tighten your safety belt, put on your shoulder harness if you have one, and secure all loose objects.
28.2.2 Plan and hold your course to take you through the storm in a minimum time.
28.2.3 To avoid the most critical icing, establish a penetration altitude below the freezing level or above the level of .15 C.
28.2.4 Verify that pitot heat is on and turn on carburetor heat or jet engine anti.ice. Icing can be rapid at any altitude and cause almost instantaneous power failure and/or loss of airspeed indication.
28.2.5 Establish power settings for turbulence penetration airspeed recommended in your aircraft manual.
28.2.6 Turn up cockpit lights to highest intensity to lessen danger of temporary blindness from lightning.
28.2.7 If using automatic pilot, disengage altitude hold mode and speed hold mode. The automatic altitude and speed controls will increase maneuvers of the aircraft thus increasing structural stresses.
28.2.8 If using airborne radar, tilt the antenna up and down occasionally. This will permit you to detect other thunderstorm activity at altitudes other than the one being flown.
28.3 Following are some Do’s and Don’ts during the thunderstorm penetration:
28.3.1 Do keep your eyes on your instruments. Looking outside the cockpit can increase danger of temporary blindness from lightning.
28.3.2 Don’t change power settings; maintain settings for the recommended turbulence penetration airspeed.
28.3.3 Don’t attempt to maintain constant altitude; let the aircraft “ride the waves.”
28.3.4
Don’t turn back once you are in the thunderstorm. A straight course through the storm most likely will get you out of the hazards more quickly. In addition, turning maneuvers increase stress on the aircraft.
29.
Wake Turbulence
29.1 General
29.1.1 Every aircraft generates a wake while in flight. Initially, when pilots encountered this wake in flight, the disturbance was attributed to “prop wash.” It is known, however, that this disturbance is caused by a pair of counterrotating vortices trailing from the wing tips. The vortices from larger aircraft pose problems to encountering aircraft. For instance, the wake of these aircraft can impose rolling moments exceeding the roll control authority of the encounter-ing aircraft. Further, turbulence generated within the vortices can damage aircraft components and equipment if encountered at close range. The pilot must learn to envision the location of the vortex wake generated by larger (transport category) aircraft and adjust the flight path accordingly.
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