I lean towards error with the inertial nav. Another KAL plane in 1978 was flying from London to Alaska, once it approached the North Pole it made almost a 180 degree turn and headed back south towards Murmansk. Those guys were luckier than KAL 007, they managed to bring it down on a lake near Olenogorsk.
Crews might've 'cut the corners' - turning a few minutes late and slightly overflying - but flying directly over Petropavlovsk, no way.
DILBERT: I told you wrong in post #5. KAL 902 was flying from Paris to Anchorage, not London to Anchorage, when it was hit by a Soviet missile and forced to make an emergency landing on Korpiyarvoe ozero near Murmansk on April 20th, 1978. Two passengers were killed by shrapnel from an Anab missile launched by a Su-15 interceptor in what Pravda at the time called 'a warning shot'.
The Soviets at the time explained away their callousness with a familiar line: It was thought that the airliner was an RC-135 reconnaissance aircraft. The success of this cover story probably led to Ogarkov's disastrous briefing five years later.
Alberta's Child: Perhaps you are right about the sloppy KAL flight procedures. Six years after the shootdown, KAL was held liable unlimited damages due to "willful misconduct" in straying over Soviet air-space. A US Federal court ruled that their misconduct was "an intentional act performed with knowledge of likely injury to passengers" and with "reckless disregard of the consequences."
And I used to think Iceland Air was bad ;-)