It would be. A nice idea to have two different types of slots, one for small and mid long routes and for longhaul over 1500km. This would make it possible to make long haul trips later in the game like it is in real live. There is no difference today between where the airplane is coming from. It would be nice to see the difference.
Mike
physically speaking, how long the aircraft has been in the air prior to landing or how long it will be in the air after take off makes not the slightest difference to the fact, that it blocks the runway when it’s on it. 
I see your point, however, it is part of your business concept. anticipate the limitations, act accordingly. plus: this doesn’t neccessarily mean you can comfortably build up your hub because enough other players might just as well use up all the “long haul slots”.
In general, this game, IMHO, is way better than all other economic simulations out there, because it actually got limited resources. slots are one of them. so you literally have to "deal with it"
I like this idea, this could be weighted to the cities with many airports also?
For example Glasgow PIK (Glasgow Local) would have more shorthaul, whereas Glasgow GLA (International) has more longhaul.
Same with London, Paris, Frankfurt etc
Paul
I understand the business concept of the game, but this does not mean it cant change.
Example: Amsterdam Airport wants to have more longhaul flights than shorthaul and they will give longhaul carriers more priority than shorthauls. So real live events are something to add to the game.
Also its more realistic to have longhaul from JFK, CGD, AMS, LHR than from Lutton, Stansted. or La Guardia in NewYork. I dont even remember if there are any longhauls out of LGA.