From: Winnipeg, MB
More probably, it didn't actually sink. Did you notice any planes destroyed on the ground?
That many days after the battle you can't rely on aircraft losses for confirmation. Very likely the damage levels became high enough a day or two before sinking for the embarked air units to fly off to the nearest land airfield.
I haven't seen this happen, unless the planes are already in the air. If the ship failed a DC roll prior to planes being launched for missions (CAP, search, etc.), they'd all still be onboard. Planes destroyed on the ground is a pretty reliable indicator of CV sinkings, even days after the battle. For me, anyway.
Doesn't that depend on whether the damage it suffered was over 50% to prevent the aircraft from subsequently flying off? I don't know for sure but I think the AI scripts would fly off the air groups if damage was a bit below 50% and climbing. Any human player would likely do so.
No matter how bad a situation is, you can always make it worse. - Chris Hadfield : An Astronaut's Guide To Life On Earth