One time the last few month there was a change introduced - no first class demand on international routes (up to 2400nm).
Besides the fact I think it's not realistic (Heathrow to Tel Aviv without First Class?) it creates a problem: Smaller routes are often needed as fill-up instead of leaving this part of the schedule blank.
Why aren't those seats simply sold as business class seats?
DC-10-30 with 56 business and 10 first class seats flying from London Heathrow to Vienna airport. Demand is about 80 business class seats and 0 first class seats. It would be nice if the first class seats are exactly handled like business seats (same comfort, same ticket price), so in our example we could sell 66 business class seats.
Of course this could be made for only economy routes and aircraft with business class seats, too. However, I tried to make this feature request aimed to the latest change in first class demand cut on shorter routes.
I also think it could be modeled fast, so it's no time consumpting feature. Just check if the route is below 2400nm and if yes, turn first class seats into business seats.
This future request is also not aimed to fill up first class seats on long international seats with business pax the aircraft has not enough space for. It's simply to increase realism and profitability on (international and maybe longer domestic in the US) routes below 2400nm.