US Army (USA) Sergeant (SGT) Mark Vonachen (left) and USA SGT Kevin McAndrews, Flight Engineers, 160th Aviation Squadron (AVN SQN), wait by their USA UH-60 Blackhawk (Black Hawk) helicopter, for Scouts from 1ST Platoon (PLT), Echo (E) Troop, 4th Cavalry (CAV), 2nd Brigade (BDE), to board the aircraft for a Quick Reaction Force (QRF) mission. The QRF responds to immediate action situations directed by the Tactical Operations Center (TOC) commander during Operation IRAQI FREEDOM