Another problem may be that you have flights spread all over, I copied and sorted your departure and arrival times (from/to AMS) and I was not able to find any sort of meaningful waves, maybe besides the one at 4 am and 10-12 am departures. But then, you do not have arrivals in good times to support those departure banks/waves.
For so few departures per week as you have (900) and with the flights spread across all times of day you will not be able to do any meaningful long haul. Competitors will have better connection times. Doing ad-hoc flying and any departure times works at server start but is a wrong strategy. You should redo your route network (slots are not a problem on Quimby).
My strategy would be to start with 3 to 4 banks per day (spread evenly 8 - 6 hours respectively), check your average stage length, multiply by 2 and add turnaround and minimum connection time, and see where you fit, whether you can do 6 hour or 8 hour round trips Again remember to leave sufficient time for the connection time till the next departure bank
e.g. |---OUTBOUND FLIGHT---||----TURNAROUND----||---RETURN FLIGHT---||---MINIMUM CONNECTION TIME----| should fill within either 6 or 8 hour RT block.
You will need to play with flights for the best scheduling and maintenance ratio. Sometimes it will mean 1 hour waste-time at your hub (to fit arrival time close to the limit of connection time for making connection), sometimes it will mean having a 2-hour maintenance break at your outstation, sometimes it will mean having an earlier arrival time (meaning immediate return from your destination back to your hub) and that flight having a longer connection time, etc.
What I can assure you that there are concepts, but scheduling each and every plane is individual thingy, it's a tradeoff between lowest maintenance ratio and short connection times. You will need to think, and analyze each and every route you are scheduling for that very plane, and compare to the maintenance ratio, waste time, utilization, and connection times. On one plane a trip to a destination X may require a maintenance window at the destination, but on a different plane flying the same route at a different time, you will maybe need to forgo the lowest connection time and return the plane back to hub to take maintenance there. On another plane maybe you will need to cross the bank/wave-time hour in order not to have waste time in hub (by a waste time I mean the time the plane is on a ground but is not doing maintenance - the white spaces in flight schedule).
Scheduling is one of the most crucial aspects of playing Airlinesim. Everybody's tendency is to start by just scheduling flights to all places they can think of without any kind of strategy etc.As time goes by you will perfect yourself in scheduling. Just a few months ago my scheduling skills were mediocre. With each new airline I start I am getting better at that. Recently I had luck that my first airline I started (the first that took to prosper) I was able to reschedule and improve scheduling after my competitor left the game and left me 50% of slots free. I basically started from scratch and rescheduled better. Now with AGEX at low 700's (on Tempelhof) I am not even noticing a drop in revenue. And I fly with the seats I that are just average for the given travel class, on all domestic routes with that airline, with having planes virtually full! The power of good scheduling.
One last piece of advise I will give you: Try to schedule flights to similar bar-value airports (e.g. 7 bars, 8 bars etc.) on the same plane. Try not to schedule a flight to a 9-bar airport and a 4-bar airport on the same plane. While maybe at the present time with high AGEX all the flights are filling up, at times with low AGEX you will thank me, when you will have half of the flights on a plane doing a 9-bar trunk route full, and flights doing 4-bar feeder with a 50% load factor. There, it will not be easy to just switch planes or seating, as you would be forgoing a large portion of passengers on a trunk route when switching to a smaller plane. So keep your routes/destinations uniform on a specific plane, do not go for more than a 1-bar difference in airports (e.g. 9 bars and 8 bars, 6 bars and 5 bars, etc.) when scheduling a particular plane.
Hope this helps.
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