Corporate Air Services HPF821 was a transport aircraft delivering weapons via clandestine airdrop to the Nicaraguan Contras which was shot down over Nicaragua on 5 October 1986 by a surface-to-air missile.

Two U.S. pilots, Wallace "Buzz" Sawyer and William Cooper, and the Nicaraguan nationalist radio operator Freddy Vilches died when the Fairchild C-123 Provider was shot down by a Sandinista soldier using an SA-7 shoulder-launched missile, while Eugene Hasenfus, the U.S. "kicker" responsible for pushing the cargo out of the aircraft, survived by parachuting to safety.

He was convicted of terrorism-related charges, sentenced to 30 years in prison, and pardoned a month later to return to his family in Wisconsin; at the request of Senator Chris Dodd and others, he was released in exchange for Sandinista soldiers captured by the Contras.

[1] Hasenfus was pardoned and released on 17 December, and returned to the U.S. with Dodd, in what Nicaraguan President Daniel Ortega described as a "gesture of peace by the people of Nicaragua".

The reason was that the US Congress had voted in the "Boland Amendment" to outlaw US-assistance to the Contras – including prohibiting all "funds available to the CIA and the Department of Defense from being used in Nicaragua for military purposes.