 This video shows fire behavior in long unburned Stringy Bark Forest. It's important for firefighters to have a good understanding of how different types of vegetation burn under various conditions so they can decide on safe and effective tactics. Stringy Bark Forest is one of the most dangerous fuel types in Australia. This is because of the bark, a loose covering of fine flammable fluff that covers the entire trunk and branches right up into the tree crowns. A term used for this type of bark is ladder fuel because it allows surface fire to climb vertically right up into the tree canopy. It can cause a number of problems for firefighters. First, because the fire can climb vertically, flame height and fire intensity can become so great that it makes working conditions too hot for fire crews, forcing them to withdraw. Second, because the bark is flammable and loose, it generates masses of burning embers that are lofted high up into the convection column, allowing them to easily float for hundreds of metres or even for several kilometres over any fuel breaks in the path of the fire. The loose burning embers can create significant spotting ahead of the headfire front. One of the most effective tactics to hold a large bush fire in these circumstances is to light a backburn to burn away the fine fuel from a broad area in the path of the fire under the direction of the incident controller. As part of research aimed at improving safety for fire crews, CFA and CSIRO needed to test various crew protection systems on three fire vehicles under typical bush fire conditions. This required a hot fire and weather fire danger rating in the very high category. Since a bush fire in these conditions can be difficult to control and present a very real threat, the only way to safely conduct such a hot burn was to burn out a broad fuel break around the site under mild conditions prior to the test. The video shows two types of deliberate planned fires. The first piece of footage shows fire behaviour in mild weather. The burn crew are comfortable working beside the flames, which are under a metre tall. The second piece of footage shows a hot test burn in the same forest. As the fire develops you'll notice a stark contrast in the fire behaviour.