A thermal imaging camera (TIC) like any other item of firefighting equipment has limitations. This together with the misinterpretation of the displayed image and the failure to follow standard practices and procedures could result in the inability to identify and achieve objectives that can result in a compromise of safety, effectiveness and efficiency, and potential loss of life and property. Standard safety procedures and practices must be followed, including working around machinery and hazard tree assessments.
TIC use at bushfires
The actual use and deployment of TIC equipment and operators can be tailored to suit the needs and requirements of the incident. Cameras can be used to assist during size-up and fire attack, but for bushfire their use may be more beneficial during blacking out, patrolling or rechecking previous work.
We need to consider our tasking and to have a suitable camera, hand tools and equipment for the job. Spare batteries and recharging should be considered for long duration tasks. Some small-format cameras have inbuilt batteries but may be able to be recharged in the field from a portable power bank (refer to the camera’s user manual).
Crews also need to be physically fit and capable of the work required.
TIC use for mopping up at wildfires
For small tasks a TIC can be used to assist with mopping up with the camera operators working directly with crew members or supporting other crews.
In the case that a TIC is not readily available and has been requested as an additional resource for mopping up and/or patrolling, the TIC operators may still be working directly with the on-site crews in detecting hot spots. This could be either working with or just ahead of the mop-up crews. A camera operator should never work alone so that safety is maintained.
In most cases we can ether identify hot spots visually or from experience we will know where there is a need to investigate further for them. In some instances, there may be no sign of smoke, fire or other indicators, and a TIC in these cases may detect energy that can be further analysed that would otherwise not be identified.
When an anomaly has been identified either thermally or by other means, a TIC can greatly improve efficiency. We can quickly investigate surface temperatures and assess the extent of the area that may need to be further examined. Once that is done, while opening it up and extinguishing it, we can continue to evaluate it as required. This can greatly reduce the amount of time, work and extinguishing agent needed, also improving efficiency.
Scanning procedure with a TIC at wildfires
For larger fires, establish a start and finish point as well as the depth that the mopping up is to be done to. There may be a need to prioritise the work. For example, an area with more potential for fire escape or an area where the consequences for reignition or fire escape is higher.
Ensure that the camera is set to an appropriate mode or setting if available and required. If possible, establish a baseline of how far hot spots can be identified (e.g. 5, 10, 15, 20+ metres). This baseline distance will depend on the size of spots, temperature at the surface, energy generated, time of day, vegetation, etc. This baseline will assist in determining the method or type of search pattern that needs to be done based on the conditions and depth of mop-up required.
If safe, it’s important to work on foot to ensure that you check behind, under and around objects. Scan the area visually, then with the TIC. Start the scanning further away first, then work in closer, check 360° (sides and behind you) and have the remainder of the team visually looking for hot spots and hazards. Once done, move a short distance, check around objects for hidden hot spots and then continue the process. Remember to look visually as well as scanning with the TIC for elevated hot spots including for spots in the unburnt ground across control lines.
During the later warmer periods of the day detection may be difficult and slower. If detection becomes ineffective, it may be beneficial during that time to re-check previous work if required. As work progresses, we can start to factor the typical production rate of detection and mop-up. Feedback on this will assist planners on the time taken to complete the current and other similar tasks as well as the crew numbers required.
Marking and mapping hot spots
While most small hot spots can be dealt with and re-checked by the TIC crew using the hand tools and equipment carried by the team, marking may only be required if the spot requires follow up action with water and more equipment or it may need to be re-checked. Marking and mapping in that case can be as simple as using some flagging tape and using a GPS or marking the position on a map.
The intent of marking the hot spot is to ensure that any crews following up or re-checking can easily locate the hot spot and identify the work that is required, with or without the need of a TIC. A combination of flagging tape/small survey flags and approved ground-marking paint (non-flammable) if needed can be used as required.
The level of marking can be adjusted to suit the needs of the incident, but details of the marking method need to be communicated to other crews.
With full marking, tape tied or inserted near the spot must make it easily identifiable from the road/fire edge. The spot can be scraped out with a rake or shovel, then if required a small dotted or continual painted line around objects that require work.
If necessary, also mark the edge of the road/track or fire line with tape. The hot spot marker tape should be line of sight and easy to see from that position. Information can be recorded on the end of the tape with a marking pen to indicate the type of hot spot with the distance in metres as well as a single standardised letter (optional), indicating the type of hot spot can also be used: A for ash, L for log, S for stump or T for tree, etc. and if required, a hot-spot number recorded with a corresponding GPS waypoint on a log sheet if needed.
For follow up work the GPS waypoint will enable the location to be found. From there the marking tape will enable the crew to find the spot and complete the task.
If re-checking is required, the marking tape can be left in place and can be followed up during later patrolling.
Once all work has been completed the tape can be taken down and all signs of the marking should be removed. This is important so there is no confusion with work still to be done and also environmentally.
Like any application of the use of a TIC, we need to consider the limitations of their use. Background energy from the sun may warm up rocks, patches of bare earth and other objects that may appear warmer than the hot spots that we are trying to identify. Other factors include, but are not limited to the following:
- Objects that aren’t line of sight. These can include depressions in the ground and behind other objects such as trees and logs.
- Hot spots covered by soil and ash. These include burning tree roots or material under ash or soil that has been disturbed by machinery or falling trees. If objects are either visually of thermally suspicious, we may have to scrape away material to expose hot spots.
- Water or foam may temporarily mask objects from view. However, when applying a light spay of water to a hot spot it may provide some thermal contrast to define the affected area.
- Objects that are too small to identify or too far away. We need to ensure that we are close enough to identify objects if safe to do so. Camera sensor resolution, modes and features can increase the capability of the equipment.
A TIC is not a replacement for good firefighting skills and should not be over relied on. However, used correctly they can greatly improve our efficiency, effectiveness and safety. Get to know the features on your camera, its capabilities and more importantly the limitations.
For more information, email G.Parker@cfa.vic.gov.au