Exhaust-plume hazards
Exhaust plume (TC AIM AIR 4.15.1): visible or invisible emission from power plants, industrial production facilities, or other industrial systems. Releases large amounts of vertically-directed unstable gas.
Not jet blast or wake turbulence:
| Hazard | Source |
|---|---|
| Exhaust plume | Stack/tower gas emission (this lesson) |
| Jet blast | Engine thrust on ground (jet-blast-prop-wash) |
| Wake turbulence | Wingtip vortices (wake-turbulence) |
Hazards:
- Hot plume can cause turbulence and vertical shear
- Other:
- Reduced visibility
- Oxygen depletion
- Engine particulate contamination
- Exposure to gaseous oxides
- Icing
Encounter may cause airframe damage, aircraft upset, or engine damage/failure.
Worst conditions:
- Low altitude
- Calm, cold air
- Especially near approach and departure corridors or airport traffic areas
Extent and severity:
- Some studies predict significant turbulence up to 1 000 ft above top of stack or cooling tower.
- Worse: hot plume, calm, stable, cold surrounding air. Crosswind helps dissipate it.
- Stack/tower size is not a good indicator of severity. Indicators: heat and size of effluent, ambient air temperature, wind speed.
- Smaller aircraft affected at higher altitude than heavier one.
Mitigation:
- Fly upwind of a known or suspected plume when able.
- Stack with no visible smoke may still be in full operation: treat whole area with caution.
- Check Canada Flight Supplement (CFS) for known plume-emitting structures (cooling towers, power-plant stacks, exhaust fans).
Report hazardous encounter to facility in radio contact: time, location, intensity (light, moderate, severe, or extreme).
Trap: no visible smoke does not mean no plume; treat every known stack as potentially live.
References
- TC AIM AIR 4.15.1