Aerial Firefighting Limitations

There are a number of factors that may potentially limit their ability to operate and/or their effectiveness during aerial firefighting operations.

Warm atmospheric conditions

Aircraft operate more efficiently in "denser air".  As temperature increases, air density decreases, having a dramatic effect on aircraft performance.  The result being that on very hot days, aircraft may need to significantly reduce their load capacities in order to safely operate.   High air temperatures and low relative humidity will also reduce the longevity and overall effectiveness of firebombing operations on the ground as the water content will be rapidly evaporated. 

Strong winds

High wind speeds can reduce the effectiveness of firebombing operations through reduced accuracy of drops due to wind drift; increased fire intensity and rate of spread requiring faster aircraft turnaround times and the production of severe turbulence which may make aircraft operations unsafe.  If wind conditions are severe enough, aerial firefighting operations will be "suspended" until conditions abate.

Low visibility

All aerial firefighting operations are conducted according to Civil Aviation Regulations of Visual Flight Rules (VFR).  This in essence means the pilot of an aircraft must be able to see and avoid terrain and other aircraft, as well as navigate by visual references.  Therefore, aircraft operations may be suspended until conditions improve and pilots are able to operate under VFR regulations. 

Low visibility may also reduce the effectiveness of firebombing operations as targets and hazards in the fire area may become obscured or undetectable, making conditions unsafe for aircraft to operate within.   Reduced visibility from fog, dust, smoke or cloud may also restrict aircraft from taking off and landing at an airbase.   

Flights at night

Civil Aviation Regulations preclude firebombing operations at night, as all VFR operations must commence and conclude between "first light" and "last light".  First light should be interpreted as the beginning of civil twilight, and last light as the end of civil twilight.  For additional safety, CFS Standard Operating Procedures require all aircraft to be "on the ground" 30 minutes prior to last light, ensuring adequate time to safely return to an appropriate airbase. 

Availability of ground support resources

Firebombing operations are only effective if followed up with intense suppression activities by ground firefighting resources.  The main objectives of firebombing are to knockdown a fire edge, slow or halt its rate of spread, long enough for ground resources to access the fire line and mop up or supplement the knockdown process.  If ground resources cannot access the fire edge due to terrain or access, then the fire over time will rekindle.

Obstructions

Vertical obstructions such as power lines, weather masts, radio and television transmission towers, tall trees and wind turbines close to a fire area may limit aerial firefighting operations.  Where obstructions do exist, a dynamic risk assessment is undertaken by the pilot in command prior to aircraft being committed.  In some circumstances aircraft will not be utilised because risks caused by vertical obstructions exceed safe operating conditions.