In simpler words:
AV is the old 'lead your target' issue from fighter, tank, and naval big gun sims. It has no meaning for a computerized fire control system where 'target lock' is everything. The SFB designers understood this nifty bit of technology and wrapped it all up in EW.
The delta AV that Cleaven referred to is any maneuver that changes the parameters of speed/course that were in existence at the moment of firing. That would be erratic maneuvers.
High AV does increase the difficulty for the automated tracking/targeting systems but not to the degree that EM should. AV as implemented in SFC3 is questionable. The games current values place much more emphasis on AV than on EM.
Again, not really true. As I have said many times, AV is really a minor factor in SFC3, Range & both Evasive & Erratic Maneouvres matter far more. You fly with Erratic Maneouvres on in SFC3, then the opponents accuracy rate drops by a good 40%, even higher with Faster Ships. AV doesn't exactly change much anyway, until you reach point blank range, the AV is usually below 30, not enough to have any major effect on the weapons.
The difference in SizeClass, the most overlooked value in SFC3, is one of the largest factors on the game when it comes to accuracy. If you give a ship a Size Class of 100, you CANNOT miss it, AV, Evasive Maneouvres, even Erratic Maneouvres won't make a darn bit of difference. In fact, it's probably THE most important factor. You have a ship which is considered "smaller" than your opponent, by Size Class, then you are going to evade more heavy weapons.
A skilled pilot can make ANYONE miss, even at Range 10-20 with an AV of zero.
Weapon Accuracy at Range is what is the major issue, it's a "luck" factor, and it's too high. At long range heavy weapons have accuracy ratings of 20-30%. That's just too low to be even remotely realistic. Because of this, it's impossible tell how much AV is really affecting the weapon. I'd hope that if the AV's of two ships at the point of fire stayed exactly the same throughout the torpedoes movement, then the Torpedo would hit no matter how high the AV was.
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I still don't like EW, I just can't see how it makes sense at all. We've seen many times that if you can pick up even the tiniest trace of a ship location, you can hit it. I also doubt that any Computer that advanced could be jammed so easily. AV may not make sense, but EW just makes even less sense.