3/21/24
AIM
and/or engine damage/failure. These hazards are most critical during low altitude flight in calm and cold air,
especially in and around approach and departure corridors or airport traffic areas.
Whether plumes are visible or invisible, the total extent of their turbulent affect is difficult to predict. Some
studies do predict that the significant turbulent effects of an exhaust plume can extend to heights of over 1,000
feet above the height of the top of the stack or cooling tower. Any effects will be more pronounced in calm stable
air where the plume is very hot and the surrounding area is still and cold. Fortunately, studies also predict that
any amount of crosswind will help to dissipate the effects. However, the size of the tower or stack is not a good
indicator of the predicted effect the plume may produce. The major effects are related to the heat or size of the
plume effluent, the ambient air temperature, and the wind speed affecting the plume. Smaller aircraft can expect
to feel an effect at a higher altitude than heavier aircraft.
b. When able, a pilot should steer clear of exhaust plumes by flying on the upwind side of smokestacks
or cooling towers.
When a plume is visible via smoke or a condensation cloud, remain clear and realize a plume
may have both visible and invisible characteristics. Exhaust stacks without visible plumes may still be in full
operation, and airspace in the vicinity should be treated with caution. As with mountain wave turbulence or clear
air turbulence, an invisible plume may be encountered unexpectedly. Cooling towers, power plant stacks, exhaust
fans, and other similar structures are depicted in FIG 7
Pilots are encouraged to exercise caution when flying in the vicinity of exhaust plumes. Pilots are also
encouraged to reference the Chart Supplement where amplifying notes may caution pilots and identify the
location of structure(s) emitting exhaust plumes.
The best available information on this phenomenon must come from pilots via the PIREP reporting procedures.
All pilots encountering hazardous plume conditions are urgently requested to report time, location, and intensity
(light, moderate, severe, or extreme) of the element to the FAA facility with which they are maintaining radio
contact. If time and conditions permit, elements should be reported according to the standards for other PIREPs
and position reports (AIM paragraph 7
21, PIREPS Relating to Turbulence).
FIG 7
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6
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2
Plumes
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6
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17. Space Launch and Reentry Area
Locations where commercial space launch and/or reentry operations occur. Hazardous operations occur in space
launch and reentry areas, and for pilot awareness, a rocket
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shaped symbol is used to depict them on sectional
aeronautical charts. These locations may have vertical launches from launch pads, horizontal launches from
runways, and/or reentering vehicles coming back to land. Because of the wide range of hazards associated with
space launch and reentry areas, pilots are expected to check NOTAMs for the specific area prior to flight to
determine the location and lateral boundaries of the associated hazard area, and the active time. NOTAMs may
include terms such as “rocket launch activity,” “space launch,” or “space reentry,” depending upon the type of
Potential Flight Hazards
7
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6
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17