Short answers, pulled from the story.
The ICAO concluded that the autopilot almost certainly remained in HEADING mode instead of being switched to the inertial navigation system (INS) mode after takeoff from Anchorage. The plane drifted progressively further from its planned route, reaching 60 nautical miles off course at waypoint NABIE and 160 nautical miles off course by waypoint NEEVA, eventually crossing into Soviet airspace over the Kamchatka Peninsula.
Major Gennadiy Osipovich, the pilot of a Soviet Sukhoi Su-15 interceptor from Dolinsk-Sokol airbase, fired two K-8 missiles at the Boeing 747 at approximately 18:26 UTC on the 1st of September 1983. The shoot-down order was authorized up the command chain through General Anatoly Kornukov and Army General Ivan Tretyak.
All 269 people on board were killed: 246 passengers and 23 crew members. Victims came from 15 countries, with South Korea accounting for 105 passengers and the United States for 62. United States Representative Larry McDonald of Georgia was among those killed.
Intercept pilot Major Osipovich stated in a 1991 interview with Izvestia that he saw two rows of windows and recognized the aircraft as a Boeing, knowing it was a civilian plane. He chose not to report this to ground controllers because they did not ask him. The Soviet Union initially denied knowledge of the incident, then claimed the aircraft was on a spy mission.
Soviet searchers recovered the cockpit voice recorder on the 20th of October 1983, fifty days after the shoot-down, at a depth of 174 meters near Moneron Island. The Soviet government concealed this for nearly a decade. Russian President Boris Yeltsin released the recorders to South Korean President Roh Tae-woo in November 1992, and the tapes were handed to the ICAO in Paris on the 8th of January 1993.
President Reagan issued a directive making the Global Positioning System freely available for civilian use once it was sufficiently developed. The United States also altered tracking procedures for aircraft departing from Alaska. The Convention on International Civil Aviation was amended in May 1984 to prohibit the use of weapons against civil aircraft in flight; that amendment came into force on the 1st of October 1998.