Suggestions with regard to the Handling of Connection flights:
1. Pricing: the baseline pricing is based on the non stop distance between the departure and arrival points (much as it is done today). The revenue is then allocated ex post between the flights (and/or carriers) on a prorating basis. (As is done in RL). Rather than today's free market prices this would be closer to the way prices were set in the IATA days - old fashioned may be must much simpler to determine and manage (at least for the default values)
The pricing - how player manages pricing - can always be fine tuned later, some interface can be build for that, but to get something going, it can for the first version be simply sum of the legs of the flight.
2. Routing and pax distribution: total travel elapsed time is the main parameter. Passengers will a priori chose the shortest travel time and only fall back on more time consuming alternatives if there is a price advantage. Different types of passengers F/C/Y value their time differently and prices per hour could be set for each type of passengers in their choice algorithm. The price and time elasticity es could therefore be merged in a single demand curve/equation
I am not exactly sure how this can be modeled, but the there should also be some fluidity between Y, C, F, related also to seating quality. I don't think these should be distinct classes of demand, but should flow from one to another. If there is not Y or C seats, the F traveler will not simply give up, and not fly, he will fly in other classes.
Also, if there are no more Y seats, it is completely sold out, some Y pax will pay the higher price for C. Also, if the aircraft has, say, 10 C seats, and there is no demand for them. If a player sets the price of the C seats lower, let's say as low as Y seats, those seats should sell in a heartbeat.
Agreed with you about the total time being the most important factor, which would automatically (and very strongly) favor direct flights in pax allocation. No need to hard code special penalties for transfers / tech stops. Of course, a 1500nm direct flight in an HD seat on a Turbo Prop would not just automatically win over connecting flight on a jet.
3. Connecting times: each airport should have its own minimum connecting times based on its size and also whether the connection is domestic only/domestic-international/ or international. (Security and immigration considerations make these different)
That sounds like a refinement that can be added later on.
Ps elapsed time would also be a good parameter to allocate demand between aircraft with different speeds (props/jets/Concorde) and replace the current penalty for flights with a technical stop.YES
That was such a bad decision to hardcode the tech-stop penalty to completely destroy a valid strategy. As if passengers wanting to travel to a certain destination simply abandoned / postponed their plan for 30-50 years, knowing that Boeing will launch of 777-200LR in 30-50 years, and then they can complete their trip. If there is a superior choice, a non-stop flight, that should get a strong preference, due to shorter total time. But if that option is not available, half of the demand should not just disappear, as it currently does...
From the POV of a passenger, tech stop is no worse than a connecting flight, and people take connecting flight all the time.
If I want to go on vacation, I pick a place where I want to know, and then figure out the flights to get there. Not the other way around. Looking first where I can fly non-stop, and if it does not include my destination, I will not simply cancel my vacation.
PS2: how many stopovers should be included (1,2,3?) may be 1 for flights less than 1000 nm, 2 less than 3000nm 3 for more?
That's a good point about the distance. I would say 3 is excessive, but for some far away places, it would be great if the system could model 2 stopovers.