Same thing here with 19.3 experimental, CTD when successfully shooting down an air superiority flight of three ufo fighters.
Here a savegame just prior to the engagement:
https://dl.dropboxusercontent.com/u/32762861/2013-07-06_21.01.36.sav
edit:
shooting down just one of them and then disengaging causes the remaining two planes to disappear from the geoscope. Trying to intercept another ufo flight then leads to an instant CTD on the geoscope, when clicking the "intercept" button.
Guess I am waiting for 19.4 as well now.