“These experiences become engrained in your mind, and never go away.” March 29, 1973, marks the day when then-Capt. Robert Certain was released from a Hanoi prison during Operation Homecoming. “Every year between Christmas and Easter becomes an anxious time for me remembering those Prisoner of War days,” Certain said in an interview with Air Force Times. This year marks the 40th anniversary of his release. On Dec. 18, 1972, President Nixon ordered a campaign against military targets in the cities of Hanoi and Haiphong during the Vietnam War, known as Linebacker II. A part of the 340th Bombardment Squadron…