In the AircraftObject.INI file, I read about altering a
line entry here:
[AIData]
AileronDeltaRoll=1.3
AileronRollRate=-1.0
ElevatorDeltaPitch=1.0
ElevatorPitchRate=-0.1
ThrottleDeltaSpeed=0.1
ThrottleVelocity=-0.008
MaxPitchForAltitude=25.0
MinPitchForAltitude=-15.0
PitchForThrottle=0.0
PitchForAltitude=0.008
PitchForVerticalVelocity=-0.1
RollForHeading=2.0
RollForHeadingRate=-0.6
MinRollHeading=5.0
MaxRollForHeading=15.0
PitchForRoll=0.25
FormationSpeedForPosition=0.8
FormationSpeedForRate=0.45
GunnerFireChance=80
GunnerFireTime=2.5
GunnerAimOffset=0.0050
MaxRollCombat=60.0
MaxPitchCombat=50.0
MaxRollFormation=5.0 <------------(30.0 is the original)
FormationRollForPosition=0.001
FormationRollForVelocity=0.1
RollForGunAttack=0.5
RollForGunAttackRate=-0.1
CannonFireAngle=45.0
The aircraft seem to stay in formation better

Get this file
using the CAT extractor utility.