In later stage of one server, we all find it is very difficult to schedule to add flight in busy airports since the slots are always irregular. I find the slots problem is mainly resulted from the scheduling of flights last for more than 12 hours.
Most of us want their schedule to be regular, that is, we want the flight of ICN-BOS depart at 16:20 everyday, the flight need 27 hours to get back. To utilze it in daytime, I schedule ICN-SIN daily. So we need three aircrafts to run a daily flight. As a result, plane 1 runs 1,3,5, plane 2 runs 2,4,6, plane 3 is need to fly on Sunday only. After the scheduling, plane 1 and 2 all have some time left. I will put two ICN-NRT flight in plane 1 and 2. And plane 3 is left, I have to put some other flights in plane 3.
If I have only two planes, I have to change the depart time so as to put the Sunday flight into the plane 2.
So the slots become irruglar in ICN, what is worse, the airports the plane 3 fly to is also irregular. And the problem will pass to other airports, too.
In real world, Thai Airways need only two 747s to run BKK-MXP daily(need around 29 hours to get back) and BKK-PEK daily. To reflect the real world, we can find ways to solve the problem.
Requirement, need two identical aircrafts, two airport have regular slots in certain time. For instance, ICN 16:20, 21:10, BOS 20:25 22:50. If all the regular slots are taken and no regular slots exist, this method can't be appied.
When scheduling, the scheduling page only show day 1 and day 2 of plane1, all irregular slots are red and regular slots are available. The ICN-BOS-ICN occupy the time 16:20 of day1 21:10 of day2. After that, the ICN-SIN-ICN can be scheduled the same way, plane dapart day 2 night and return day1 noon time. Plane 2 occupy the the rest.
For slots in ICN,BOS,SIN, the slots are occupied daily.
After the scheduling, the two planes' schedule can be only appied or terminated at the same time.
I believe this method will make the scheduling process easy and the slots problem is solved in a practical way.