When a pilot is flying a forest patrol, he cannot always fly the direct route. He diverges from his course to accurately locate and secure the limits of each fire which he sees. Then, again, the smoke pall may obscure the tops of the mountains and require for safety’s sake that the plane be flown through valleys or around peaks to reach the destination. Thus on most patrols, while the flight could be made in two hours if the sky was clear and there were no fires located, during the fire season the plane might be out as long as three or even three and a half hours.