Regarding Flight 007 that got shot down in the Soviet Union, this was reported in the New York Times:
Study Says Korean Airliner Was on Its Intended Course When Downed in '83 (nytimes.com)
Excerpt:
A retired airline navigator has gathered evidence that in his view shows that the South Korean airliner shot down over Russia in 1983 was on a deliberate flight path and did not stray accidentally into Soviet territory.
A principal part of his analysis is his refutation of what has been the prevailing theory, that the plane unintentionally flew off course because of a single-digit mistake in keying flight coordinates into the navigation system.
Leading aviation officials accept the refutation as correct, but still insist that the incursion was accidental and not deliberate.
We know this was a modern (at the time) Boeing 747 with a complex inertial flight management system.
No, I do not believe the theories about this being intentional. Nobody would risk a plane full of passengers like this on purpose.
In 1978 the KAL flight 978 went astray and was forced down on a frozen lake inside Russia.
Korean Air Lines jet forced down over Soviet Union - Apr 20, 1978 (history.com)
I would think this would be on their mind as they prepared for the flight.
So my question is: How did KAL 007 get so far off course?
Follow-up: Wouldn't they have noticed?