Ask for help,please!

why can’t my own aircraft be sold into cash after the dissolution of my subsidiary, and then the cash goes back to the parent company?

It does not happen this way. You have to transfer the plane to your holding / parent company before you delete your sub.

That’s what I did before

When you liquidate any enterprise with owned aircraft, those will be sold to AS, but for a rather low price. If you can see a future use for your aircraft, you should definitely transfer it before. I you want to get rid of the aircraft, you’ll get the most money out of it by seeking on the aircraft market.

For you specific case, it’s most likely that the sale revenue just wasn’t that much and other costs for laying off your staff were higher, so there was no money left to be returned to the parent company after the liquidation was complete.

If you did, the plane should now be yours. Or you did not transfer it via asset management tool.

When I liquidate, I have 24 E95 and several A320 series

Will it be double slots after game update?

Were all of those aircraft fully owned? Still doesn’t say much about the total value and liabilities though…

No, double slots are only a setting for specific game worlds - currently Otto, Blériot and Domination.