Five firefighting planes are grounded indefinitely, while the National Transportation Safety Board comes up with a reason for this week´s firefighting crash. NTSB spokeswoman Lauren Peduzzi says the investigation could take a year. The Forest Service grounded the C-130-A airtankers after the wings of one of the planes broke off in flight Monday near Walker killing three crew members. Currently, there are enough airtankers in the firefighting fleet to battle existing fires. If more blazes break out, military planes from the Air National Guard and the Air Force Reserve are available.