AI routines in 4.11 have been modified extensively in order to introduce several limitations
that human pilot would experience. Below is a list of things player can expect to see in 4.11:

Various new AI maneuvers have been added. Number of maneuvers is increased by 25%.
AI planes will no longer detect enemy planes automatically inside certain radius. Position and
size of enemy plane is the main factor here. Bigger plane will obviously produce a bigger and
more visible "dot" and it will be more visible to AI.
AI skill will generally determine how well AI can spot targets. Also every gunner on board will
contribute to enemy spotting by covering their own sectors.
Generally pilots will keep looking more forwards than backwards. Occasionally fighters execute
fishtail maneuver to get better view behind. Planes will be less visible against dark background
like land, but more visible against brighter background like sky and clouds.
Clouds & land mass blocks AI's ability to see other planes behind them. For example it is
possible to evade attacking AI plane by hiding in clouds. AI planes will also try to hide in clouds
in certain conditions.
AI's own plane will block their line of sight. This is calculated from the plane's collision model.
For example basically all planes cannot see directly below them, unless the plane has
ventral/bottom gunner that can cover the underside. For example plane like Blenheim has
blind spot rear & behind since it has no tail/bottom gunner. Plane like B-17 with bottom/rear
gunners cannot be surprised from rear & behind like Blenheim (during daylight).
Occasionally fighters will execute roll maneuvers to get a look directly below them.
When fighter is pulling positive G's to get a lead shot and target goes invisible under nose, AI
will not see the target. Instead of aiming at the actual target, AI is shooting at estimated
target which position is extrapolated based on the last real observations. Much like human
brain would do.
AI pilot's ground collision detection is improved and now they will detect ground obstacles in
front of them better. Previously AI always crashed into certain kind of hill/mountain which has
too steep slope.
Environment factors such as darkness affects how well planes can be seen. AI is blind against
attack from sun and planes show up better as silhouette against moon. Planes are spotted
more easier if they emit smoke, fire, condensation trail or have lights on or are illuminated by
searchlight.
Also ships & ground AAA and aircraft gunners have the same clouds/ground/environment
restrictions as AI pilots.
AI gunners check before shooting that there is no friendly planes in front/behind their enemy
target.
AI gunners don't keep shooting while the gun is turning towards target and the target is
nowhere near when the bullets would go. So gunners will no longer waste ammo for stupid
shots.
Gunners will be less accurate shooting targets that move fast. In other words target that
forces the gunners to turn guns fast is less likely to get hit.
Gunners that experience too much positive or negative G's cannot fire at all.
AI plane's engine will overheat forcing AI to reduce throttle and open radiators.
AI planes respect diving limits of their planes.
Changes have been made in AI deflection shooting. AI calculate deflection better but it is still
not perfect. AI's ability to chose correct deflection and to hold steady aim vary with the skill. AI
Aces shooting ability is now at human aces level and if they get into your close six you will be
in trouble.
AI flights doesn't go into attack as soon as they spot the enemy anymore. Depending on the
situation AI might try to avoid fight or try to improve their position before commencing the
attack.
AI skills are now divided internally into sub-skills and thus provide finer distribution of skill.
Aces are still better than Veterans and Averages are better than Rookies but not all AI pilots
with the same skill are the same. Some fly better, some shoot better. Some are braver and
some see better. This makes their behavior less predictable.
In addition to the maneuvers, AI fighter defense is completely reworked, no more constant
rolls. AI will perform diverse maneuvers and provide bigger challenge to the player.
AI will make mistake too. They will stall and spin occasionally, panic and “freeze” and
sometimes they will even bail out before you fire a single bullet at them.
Note
If AI planes in player’s own flight have not noticed the enemy planes, player has possibility to
“point out” the enemy presence to the friendly AI planes by padlocking enemy plane so that it
is visible at roughly center of the screen (15 deg. cone). This works even if the padlock is not
enabled. Also the commands attack all/bombers/fighters has the same function built in as the
padlock key. So issuing “attack fighters” command to your wingman would fail if your wingman
has not seen the enemy and you give the command while you don’t see the enemy. Giving the
command when you see the enemy at the center of your screen (in cockpit) gives your
wingman the direction of the enemy and wingman can attack it. This prevents abusing the
attack commands like a radar.
The AI development is a continuous process we plan to refine further for 4.12. We would like
to ask you to report any odd AI behavior we may have not noticed during our beta testing. It
was not possible for us to test all AI situations / routines.
Checks concerning clouds are not working on dedicated server. DS doesn't know anything
about clouds and was never designed to have AI planes, but we will try to change this later.

4.12

Improved land avoidance

AI changes

AI ability to avoid land ahead improved significantly, up to the point where fighting inside the canyons is possible. You can quickly check the new behavior in the provided demo mission (Missions/412_Demo_Missions/MountainFight.mis).

• AI detects when AAA is shooting at it

When AAA is shooting at the AI controlled planes that's detected by AI and in some situations AI will change its behavior. In case of flying from Waypoint to Waypoint they will make small changes in course. During ground attacks AI will take shots from longer distance and try to deploy all of the rockets as fast as possible to minimize the time on defended targets. They will not go to the climb right after the attack either, they will first extend in low level flight first and reposition for a new attack when they gain some separation from the target.

• Shooting model changes

AI shooting ability changed to make it more human-like.

• AI taxiing waypoints for take off

Mission builder can insert taxiing waypoints for AI planes so that AI planes will taxi from initial spawn point to the take off point. This feature works best with the stationary plane spawn point (see 4.11 patch guide). View the provided demo mission to see an example how the taxiing is used (Missions/412_Demo_Missions/AITaxiing.mis).

The most important update by TD is the AI, which is much more challenging and realistic now, in my opinion. Widescreen and TrackIR 6DoF are now also standard and the number of game-play options has been increased. However, if you do not use mods you are going to greatly miss out as there is just released a single, transformative mod for 4.12 which utterly changes the game in a multitude of ways and for the better.

This... but I have to also say... give HSFX a shot as a mod pack.. Also before you do that make sure you back up your IL2 instal once you get your stuff set up....

I see some new aircraft have been added, such as the Hs 129 and Kate. Do they have DGEN careers for them?