As explained in exhibit 13E (and repeated in post #259 by me) the radar reporting the altitudes varies in accuracy by +/-3000ft when the contact is within 100 miles. Its inaccuracy increases significantly outside of 100 miles. The P-3 was roughly 140 miles away. If you match the times of the contacts you will see that they occur 12 seconds apart throughout the sequence whether their reported alitude is 20,000ft or 17,600ft. Secondary returns are purely the result of IFF transmissions. Those altitude reports should be accurate. Since the P-3's IFF didn't work, the only returns are primary (actual radar returns bouncing off the airframe). Primary returns vary in accuracy each sweep. You are supposed to be the aeronautical engineer. Why do I have to explain this to "the jury"?
Incidently, you still haven't told me whether or not I'm looking at the right data on pg 42.