In many areas of the world, and at certain times of the year, wide areas of combustible vegetation can be subject to wildfires. These fires can have a significant impact on aviation operations, both in the areas directly affected by the fire(s), and in the surrounding region. This article discusses factors that should be considered by pilots, during both pre-flight preparation and in-flight operation, when conducting flights within, or near, an area with active wild fires.
A wildfire, often also referred to as a forest fire, bush fire, brush fire, grass fire, coal or peat fire, is an uncontrolled fire caused by lightning, volcanic eruption or ignition related to human activity e.g. equipment generating sparks, unattended campfires, or arson. Areas with a mediterranean climate, Köppen climate classification "hot dry-summer" climates (Csa) and "cool dry-summer" climates (classified Csb) are particularly susceptible to wildfires.
Although by no means a new phenomena, wild fires appear to becoming more prevalant as the planet warms and changing climatic conditons result in localised drought. The Australian "Black Summer" bushfires of 2019-2020, the British Columbia, Canada, forest fires during the summer of 2021 and the Christmas 2021 wild fires in Colorado, USA, are all examples of more massive, more widespread, and even more unpredictable, or out of normal season, wild fires. A report published by the United Nations Environment Programme and GRID-Arendal in 2022 said, "Across Earth's ecosystems, wildfires are growing in intensity and spreading in range."
Flight Planning Considerations
In addition to the myriad of factors considered during normal pre-flight planning, special consideration should be given to the following:
- Flight Rules - Visibility, in the area of and around an active wildfire, is likely to be significantly reduced due to smoke. Flight in accordance with Visual Flight Rules (VFR) may not be possible. Likewise, a VFR only destination may not be accessible due to smoke.
- Airspace Restrictions -Temporary flight restrictions (TFR) or other methods of airspace control may be put in place to protect firefighting operations. Note that in some jurisdictions, standing regulations automatically restrict the area around an active fire. For example, Section 601.15 of the Canadian Aviation Regulations (CARs) provides that no unauthorized person shall operate an aircraft over a forest fire area, or over any area that is located within 5 NM of one, at an altitude of less than 3000 ft. AGL. A NOTAM does not need to be issued for this airspace restriction to be in effect.
- Firefighting operations - The area around a forest fire is usually a hive of aviation activity. Spotter (bird dog) aircraft, air tankers and helicopters, all working to suppress the fire, can be anywhere in the area dropping fire retardant, moving personnel and equipment, transiting to and from the fire, or picking up water from lakes and rivers. Often they are hidden by smoke and are monitoring discrete, unpublished radio frequencies. Besides contributing to the risk of collision, the presence of unauthorized aircraft can seriously disrupt the work of the fire suppression crews.
- Fire generated weather conditions - Expect moderate to severe turbulence over wildfires due to rising air caused by the heat from the fire. Convective clouds (Pyrocumulus) can be generated by this airmass instability and can reach significant heights. The rising air which generates the convective clouds can also create strong surface winds which are often gusty and subject to rapid changes in direction.
- Fuel planning - Allow sufficient fuel for delays and/or diversions, both during transit and at destination, due to changing conditions or fire suppression activities. For destinations in or near the fire zone, if at all possible, land with sufficient fuel for the next leg as fuel may be unavailable or fueling resources prioritised to service suppression aircraft.
- Alternate selection - Wherever possible, select an alternate aerodrome that is outside the fire zone. If that is not practical, ensure that more than one alternate is available.
- Emergency evacuation - Rapidly changing conditions may necessitate the short notice evacuation of aircraft and personnel from airports threatened by wildfires. Transient aircraft should arrive with sufficient fuel to depart, plan for minimum ground time, and consider use of engine running off/on load protocols if so authorised. The potential for high ambient temperatures, due to the proximity of the fire, should be considered in all performance and payload calculations, as should the potential necessity to conduct operations from out-of-wind runways due to the position of the fire.
A firefighting airplane dropping fire retardant on the Flagstaff Fire, June 2012. Author: Runingonbrains, Source: Wikicommons.
Ground operations at aerodromes within close proximity to a major fire can be difficult. Smoke can obscure visibility, cause breathing difficulties and irritate the eyes. Heat from the fire can result in a significant rise in the ambient temperature and negatively affect aircraft performance. Strong, gusty surface winds can impede ground operations both on and off the airfield, fan and rapidly spread the fire, carry smoke a significant distance from the fire location, and potentially carry embers from the existing fire starting new ones. Pilots should be prepared for:
- Difficult and potentially dangerous conditions for conducting aircraft preflight inspection;
- Potentially conjested ramps due to utilisation by aircraft conducting fire suppression or personnel evacuation operations;
- Delays in ground services due both to conditions and to increased demand;
- Restriction or suspension of refueling activities due proximity of the fire;
- Delayed arrival of passengers and/or freight due to conditions outside the airport perimeter;
- Runway changes due to change in wind or to fire movement;
- The need to depart urgently due to changes in the path and trajectory of the fire;
- The need to conduct out-of-wind or Tailwind Operations and the performance implications thereof;
- Low visibility operations in smoke; and,
- At takeoff, difficultly in visually confirming there are no aircraft or vehicles on the runway or aircraft on approach. This associated risk is greatly exacerbated if operating from an uncontrolled aerodrome.
Once airborne, be cognizant of the fact that the situation within the fire zone is dynamic and can change very rapidly. The planned destination or alternate aerodromes can be rendered unusable with little warning. Fire suppression assets may be redeployed and associated airspace restrictions changed in response to movement of the fire. Pilots should:
- Wherever possible, take advantage of the additional protection and traffic separation offered by instrument flight rules (IFR);
- Remain clear of restricted airspace and, if published, remain within transit corridors;
- Closely monitor conditions at destination and alternate aerodromes;
- Make appropriate position reports, especially whilst in uncontrolled airspace;
- Maintain a listening watch on appropriate mandatory frequencies (MF) and on emergency frequencies;
- Be mindful of the turbulence associated with wildfires;
- Maintain a good lookout and understanding that low visibility conditions may exist due smoke haze from wildfires;
- At uncontrolled aerodromes, broadcast intentions on the appropriate frequencies, make all required position reports, and follow the IFR or VFR protocols, appropriate to the rule status of the flight;
- Make deviation or diversion decisions early. Always have an alternate plan;
- Monitor fuel status. Have a predetermined minimum diversion (min div) or "bingo" fuel at which point diversion becomes mandatory; and,
- Be aware that combustion products in smoke may be ingested into air conditioning systems, entering the cabin. Use of supplemental oxygen and/or smoke goggles may be necessary.
- Be aware of the possibility of drones flying (illegally) in the vicinity of wildfires.