There has been some discussion on the utility/need for TZ-4b. From my reading, it is meant to serve two purposes.
One is to determine the effects damage to the player’s aircraft have on individual bombing accuracy. It seems this goal can just as effectively be met by adding the modifiers from TZ-4b to TZ-4a (some already exist in both tables). Furthermore, other than for personal play value, the effects of one bomber’s results on the overall mission are likely negligible except in the case of point targets (covered by the Low Level rules). That’s why targets were bombed by formations.
The second goal seeks to quantify the impact of temporarily being knocked out of formation. Other rules already cover the initiating conditions and effects of being permanently out of formation so that situation does not need to be addressed. The question then arises, does the play value of dealing with temporarily being out of formation (primarily the conditions around defending against enemy fighters for one turn) justify the play cost of having to consult and interpret another table (TZ-4b)? In my opinion probably not, especially in light of the frequency of both conditions (being temporarily out of formation and attacked by enemy fighters) occurring during my runs.
I think that with slight modification (mentioned above) to TZ-4a, TZ-4b can be eliminated.