A pulsing light that ascended at 90 degrees

In the early 1970s, while still attending college, I was on a late-night flight from San Francisco to San Diego.  As we were flying south, I was looking out the window to the west, and saw what I first thought was Venus, but then I realized that there were clouds passing behind it, and it seemed to be moving at basically the same pace as our jet.  So I assumed it must be another plane.  But as I studied it, I realized that it was too bright to be a plane, and there were not the typical blinking green and red wing lights around it.
 As I was staring at it trying to figure out what it was, it began to pulse.  Not blink, but pulse, at first slowly and then faster and faster.  As it began to pulse very quickly, it suddenly shot straight up, not at a curve, but a 90 degree ascent, and was gone in less than a second.
 I have no idea what it was, but it defied all the law of physics as we know them today.
Witness indicates that date of sighting is approximate.  PD