British troops of 1419 Flight, 78 Squadron British Royal Air Force, mark distance for U.S. Marine Corps pilots of Marine Heavy Helicopter Squadron 464 (HMH-464) during a Tactical Recovery of Aircraft and Personnel (TRAP) mission, undisclosed location, Helmand Province, Afghanistan, September 15, 2011. HMH-464 performs TRAP missions in order to retrieve U.S. and U.K. Armed Forces equipment and conduct investigations in support of International Security Assistance Force..