Total NOy was determined on the Pacific Exploratory Mission-West A using two separate instruments, one operated by Georgia Institute of Technology and one by Nagoya University. The two data sets exhibited significant disagreement, with no systematic correlation, and differences often a factor of 2 or more. Additionally, regardless of data set chosen, the total NOy was much greater than the sum of its components measured separately. A panel was convened by NASA in July 1993 to examine these conflicting datasets and the question of “missing NOy” on this mision. This paper reports the conclusions and recommendations from the panel.