Inquiry - ticket sales per class

[SabakuLuchtvaart]

I cannot find any discussions on this in the forums:

If an aircraft is configured business/economy or all economy, would the first class demand purchase tickets on the available flights that are c/y or all y ? Same for business on all y flights?

And the same if no business is available, however first is available, would business demand purchase the first or economy ticket?

[knobbygb]

Neither. You just lose those passengers.