 In headfires, the fire travels in the same direction as the wind. Headfires produce the fastest rate of spread, highest flame lengths, and most intense fires. To manage this intensity, headfires are often set in strips. This is called a strip headfire. In this example, the wind is moving towards the west. Parallel lines of fire are created. The spacing of the lines depends on sight characteristics, personnel, and goals. The first line is started on the downwind side of the site. Moving upwind, more lines are started. Wider spacing between lines will result in more intense fires. Closer spacing will mean less intense fires but a longer time to complete the burn. Intensity will increase where two lines converge. Headfires are effective in forests with light fuel loads because they move quickly past the root collars instead of lingering at the tree base. Familiarity with fires is more critical when using headfires because the fire will often move faster than a human can run. Headfires also tend to throw more embers in the air which can be carried by the wind and lead to fire getting out of the desired area. However, because of the faster rate of spread, headfires allow experienced burning crews to be more efficient.