[Pursuivant]

Bombers in formation shouldn't make serious evasive moves, but should be able to make minor movements as long as they keep their same basic heading and keep their distance from other bombers in the formation.

Single bombers can, did, and should make more extreme evasive maneuvers. (For example, 2LT Charlie Brown vs. Oblt Franz Stigler, Warren Cowan vs. Saburo Sakai)

That said, battle damage, crew panic, and loss of situational awareness sometimes could cause aircraft in formation to collide, particularly if they were flying in poor visibility or in close formation. So, some degree of uncontrolled movement and risk of collision is realistic.

Another oddity about AI bomber formation behavior is that bombers never "close up" when other bombers in the same flight are shot down.

For example, if you have 3 "vics," like this (3, 6, 9 are flight leaders, 9 9 is squadron leader, 2, 5, 7 are assistant flight leaders):

1   2      4    5
  3           6
      7    8
         9

and they take serious casualties, like this:

          2     4
       3 
           7    8

The flights never regroup to regain better defensive firepower and bomb concentration as they should, like this (3 becomes new squadron leader, 7 is 2nd flight leader):

    2    4    8
       3    7

Straggling (damaged) bombers also make no efforts to regroup, making them easier pickings for fighters.