I don't understand why I'm losing -1,730 AS$ in my fully booked flight, my Sukhoi Superjet has 85 Seats Standard Class Y, I have changed the cabin to 95 standard seats Class Y but will only take effect in 3 or 5 days.
but I don't think it's because of the lack of 10 seats.
Your fixed costs seem to be a bit high. I can't see all the costing details on your screenshot, so I have to guess: how is your maintenance ratio? I'ts probably to high and therefore the amount of fixed costs that is accounted for that flight is that high. Try to get your maintenance ratio close to 100% for maximum utilization of your aircraft.
Your fixed cost's are roughly twice of mine on a comparable flight (using the LR version) ... I agree, looks like a utalization issue. (My example is flying with a ration of 118%)
I don't think it is a pricing issue in first place.
Yes, many times business class is what makes a difference of losing money (or breaking even) on one side, and making somewhat decent profit (10% or more) on the other side.
And on the filler routes, operated to just get connecting pax for more profitable routes, business class can make a loss-making flight to at least break even (or lose just very little money...100-300 AS$ per flight etc.)
the weekly lease for a Sukhoi is 140.000 dollar. If your plane flies 1 return flight per day, the leasing cost for each flight (one way) is 10.000 dollar. If you schedule two return flights per day, the leasing cost per flight is 5.000 dollar. And so on. Your aircraft should be flying as much as possible.
The same goes for your pilots and flight attendants. Whether they fly or wait at the airport, at the end of the week you have to pay their salary ;-)
By the way, turnover time, landing fees, passenger handling and fuel burn per cycle (taxiing & take-off) are the same for a 500km flight as for a 1500km flight. As a result, short flights are less profitable anyway.