a quick 5 minute test scenario.
Syrians in 73, bought SA-2 guidelines. Placed near the back of of a 100 wide map. 50 visibility - but irrelevant as radar SAM. Bought 4 trucks as bait for the israeli planes. deployed in the middle of the map.
Bought the israelis 2 neshers. Plotted to arrive turn 1 and strafe the trucks.
In about 6-8 test runs, only once did the Syrians fail to fire a SAM. When they did fire, percentages were about 12-18% (before any avoidance action).
The occasion when no SAM were let off was probably a combination of low skill (low hit%) and all 4 SAM sites failing to-fire skill rolls, or the percentages to hit were too low to make the shot worthwhile (probably, israieli plane rolled high on EW and the SAM rolled low, for 2 planes and 4 possible firers = 8 opportunities).
Moral - buy more SAM if Syrian, as with 8 launchers, there is less chance of
all of them to fail a skill or electronic warfare roll simultaneously
cheers
Andy