There are airports, mostly with four or less demand, where it is no longer possible to transfer as a passenger. Somehow, I had the idea that at least at every capital city airport, regardless of the demand, it is always possible transfer. Just to guarantee that even at the tiniest countries and airports have some kind of possibility to transfer to flights, enabling to fly the world. An example is that even in Somalia - Mogadishu airport, with only one demand, a transfer is possible. Is the statement I made correct, or is it just coincidence?
And in addition: What decides whether it is possible to transfer on a certain airport or not?
The decission if an airport is transferable or not is a bit subjective of course. There is no strict rule, but there are some points to be fulfilled to receive this status. In AirlineSim it is linked to the airport-size field. Meaning we expect an infrastructure for the airport to allow a hub-and-spoke system - a minimum size of a terminal building and a taxiway system allowing to operate some aircraft at the same time at this airport. As always there are often some airports on the edge - in the one case (especially in countries with other transfer-airports) we do not make it transferable and in the other case (no other transfer airport or specific geographical importance) we have it transferable. Sometimes it helps to have a look at the terminal building, close the eyes and try to imagine how it looks if there would be at least 5 aircraft at the same time ;)
In the case of Mogadishu - it is clearly at this borderline. If the political enviroment would be more reliable, it could be one of the transfer airports.
Talking about transfers and airports, Punta Cana (PUJ) in the Dominican Republic is hardly a transfer-facility airport in real life. Anyone who has been to Punta Cana knows that such facilities are not there, and you can hardly transfer to any international flight. This is practically not possible at all. PUJ is a 100% O/D airport. You cannot even get into a transit area after your arrival, because all arriving passengers are hustled into the arrivals hall where immigration booths are 15 meters distance from tarmac in the arrivals hall. Anything that could be called a "transit area" are waiting spaces in two departure halls after clearing immigration, connected by the food court in between. You cannot just walk by yourself between arrivals and departures halls.
I had this very problem a month ago when I missed my flight by the long time it took me to get to the gate, it took me over one hour to get back "into the country", because Copa Airlines rep just left me on my own in the departures area and there was no way for me to get to the arrivals hall ... to do that you have to leave the departure halls and walk on the tarmac by the aircraft to get there! It took me one hour going from person to person until a nice soul, rep from Transaero, had pity on me and my daughter and walked us to the arrivals hall (via the tarmac). PUJ is a zero-chance transfer airport in real life!
The reason I asked is that I have started some airliners in more far-away countries like Somalia (why not! ;)) and Benin. Although, at Mogadishu (Somalia) airport, with only one demand, I can set up transfer flights. At Cotonou Airport (Benin), which has four demand, there is not such a possibility. Restricting a little bit of the possibilities to grow at Benin. Kept in mind that even Air France, Brussels Airways, Ethiopian and Kenya Airways are flying to Cotonou in real-life, it might be good to review this airport again and consider this as an transfer airport as well.
AS adds airports only if they have regular scheduled air service in Real Life. And such regular schedule must be something more than a "7-seater once a week". E.g. a daily flight on an ATR42 should be acceptable to create a 0-bar airport.
So if the listed airports in Benin lack scheduled air service, they will not be included.
(I do not speak for AS, this is my opinion based on previous discussions on the forums).
One more question. If Cotonou Airport in Benin is a non-transfer airport, which I still think isn't correct, than how is it possible that I'm having 92% direct passengers and 8% internal? Shouldn't this be 100% direct passenger flow?
fyi: I'm only flying direct flights from/to Cotonou.
Interesting! So for example, a plane starts flying at 6.00am from Dakar to Cotonou and arrives at 8.00am in Cotonou. They can stay "seated" onto the 08.01am flight to, for example, Luanda? As long as it is the same plane? And I assume they are paying passengers for the second part as well? :)
How can you improve the amount (%) of internal passengers?
That is correct. It's a large part of making money in AS. One of the factors in flight rating is the time it takes to get from their origin to their destination. Normally, a transfer time at an airport is an hour or more. The turnaround time for a flight can be pretty short, usually an hour or less. Since they can stay on the plane for the flight, they use the turnaround time instead of the transfer time.
As for increasing the number of internal passengers, you need to have good connection times, routes that work together and enough flights to make it worthwhile. Personally, I think internal transfer passengers over 30% at a hub is good, but 50% and over is optimal.