Rangers - MH-47 Chinook
U.S. Army photo by U.S. Army photo by Trish Harris
A chalk of U.S. Army Rangers with the 75th Ranger Regiment, pictured during training, set up firing position after fast-roping from a MH-47 Chinook helicopter flown by the 160th Special Operations Aviation Regiment.
In military nomenclature, a 'chalk' refers to a ground unit assigned to an aircraft.
