On March 20, 1971, Major Jack Barker and Captain John Dugan were piloting a UH-1H Huey helicopter, with Sergeant William Dillender and PFC John Chubb on board. The aircraft was participating in a troop extraction of ARVN (Army of the Republic of Vietnam) troops during the Lam Son 719 mission in the Savannakhet Province of Laos. The aircraft was hit by enemy fire. There were no survivors. In 1986, a refugee in Nakhon Phanom, Thailand showed an ID tag belonging to PFC Chubb and a medallion to a U.S. interviewer. Between 1988 and 2001, joint U.S.-Lao People's Republic teams lead by JPAC (Joint POW/MIA Accounting Command) conducted four investigations and three excavations for the four men without positive results. In 2004, another joint investigation team excavated the crash site. Remains of the four men were found. On April 12, 2006, Barker, Dugan, Dillender and Chubb were buried at Arlington Cemetery.