Since April 2006, the RAF's Chinook Force has been permanently deployed in Afghanistan, frequently under intense fire. In that time, the force has extracted almost 2000 casualties, saving the lives of many British soldiers. Flt Lt Alex Duncan is a Chinook pilot who was deployed to Afghanistan in 2010. He survived being shot down not once, but twice, and has received the Distinguished Flying Cross for his courage. Alex has written a book about his experiences called 'Sweating the Metal.'