What was a B52 doing flying that low............
Tbar
Up until the fall of the Soviet Union around 1990, the Strategic Air Command (SAC) had armed & ready B-52's to launch at a moments notice against targets I can't tell you where. This was better known as SAC Alert.
Because of the extensive network of fighter & missles defenses the Soviet Union had deployed, to only way get past those defenses was at very low altitude. Since flying at low level was the tactic that we would have to use in war, we had to practice or train while flying in that manner in peacetime. Those altitudes were typically around 400' to 600'. Wartime altitudes were, lets say considerably "less".
Trying to find places around the country where we could train wasn't easy. There were always issues of people b****in' about the noise, populated areas, airports etc. Some of the more suitable areas were the less populated areas of the western US; MT, WY, UT, AZ & NM. Since no one could predict if such a battle would be flown at day or night, we had to train under both conditions. Hence the need for flying through the mountains, at low level, at night. Unfortunately, practicing such a dangerous activity sometimes led to mishaps, which a few times I came scary close to experiencing.