What we did was a simple comparison of the Soviet General Staff study data on the air fighting in the south compared to the daily records we gathered from the Second and Seventeenth Air Armies. What we found was their were minor differences in the sortie counts, but overall that was close to what was reported in the unit records we had.
On the other hand, the reports on casualties was not. There were outrageously incorrect estimations of enemy losses, which is typical of Soviet accounts. But as significant, the reports of their own losses were low. In particular, our count of Second Air Army losses from 5-18 July was 481, their count was 371. This Soviet General Staff study only reported 77% of their losses. Does this mean that if I draw losses reports from the Sixteenth Air Army from the Soviet General Staff study (as I don’t have the unit records), should I “inflate” them by 30%? (the inverse of 0.77).
Added to that, they simply left out the Seventeenth Air Army losses (182 aircraft). It may have been an oversight or a deliberate effort to downplay their losses.
But, just to focus on the Second Air Army losses, the staff study has the total losses for the 5th – 18th as 371: 172 fighters, 31 bombers, and 168 assault. We have the Second Air Army’s losses for 5 to 18 July 1943, taken from their daily reports, as 481 (See Table IV.32 of Kursk: The Battle of Prokhorovka). This includes 248 fighters, 48 bombers, 180 assault and 5 night bombers. So actual losses of the Second Air Army were 30% higher than what was reported in the Soviet General Staff study, or 28% if one leaves out the night bombers.
One does wonder about the process where even the internal classified post-operation staff studies understate their losses (in addition to many other errors). They did have the unit records available to them. In particular, their table is vastly off on the 5th of July when the Second Air Army lost 114 planes and the Soviet General Staff study reports only 78, but it consistently underreports for every single day. They also do not report the losses for the Seventeenth Air Army, which according to our count was another 182 or 221 planes lost (see Tables IV.34 and Tables IV.35). This does argue that the reported losses for the Sixteenth Air Army may be low compared to reality.
In the bigger picture, the Soviet General Staff studies are secondary sources, not primary sources. Furthermore they are secondary sources with considerable bias and errors. They invariably (grossly) overplay German losses and seemed to try to minimize their own losses. Furthermore their narrative of accounts often downplays certain aspects of their operations. They do have be used with extreme caution, as opposed to treating them as somewhat authoritative.
Now, Niklas Zetterling & Anders Frankson offer a similar discussion of the problems of relying on the Soviet General Staff studies in their book The Korsun Pocket: The Encirclement and Breakout of a German Army in the East, 1944. It is clear that these are secondary sources with biases that must be used with considerable caution.