jas24:
mostly correct - except that the instructor in the RVAC aircraft admitted he was above circuit height (1500ft) but didn't know by how much (!!), the instructor in the other aircraft (BZA) reckoned he was not below the required 2000ft for overflying, and the radar had them at 2000ft. Even allowing that the radar fix was unlikely to be accurate, the evidence suggests UMB was 500ft high.