Extortion 17
On 6 August 2011, a U.S. CH-47D Chinook military helicopter operating with the call sign Extortion 17 (pronounced "Extortion one-seven") was shot down while transporting a Quick Reaction Force attempting to reinforce a Joint Special Operations Command unit of the 75th Ranger Regiment in the Tangi Valley in Maidan Wardak province, southwest of Kabul, Afghanistan.[1][2][3][4]
https://en.wikipedia.org/wiki/Extortion_17_shootdown