Reported sometime through support email, it is closed there since the discussion ends with its AS's will to make certain airports transferable. But I still have the question, thus bring it here for general discussion.
I checked on latest server, Riem, for Taiwan's airports, in total 9 airports larger or equal than 4 bars on PAX level, and all of them are able to transfer flights:
Name PAX bars transfer time
TPE 9bars 01:15h
KHH 6bars 01:15h
TSA 6bars 01:15h
MZG 5bars 01:00h
TNN 4bars 01:00h
HUN 4bars 00:45h
KNH 4bars 00:45h
RMQ 4bars 00:45h
TTT 4bars 00:45h
I think for TPE, KHH, TSA I have no doubt they are large airports can transfer. But for those 4 bars airports, I don't believe people transfer there.
Take TTT airport for example, from Wiki, it only has 3 routes (https://en.wikipedia.org/wiki/Taitung_Airport). And from flight status I found for example today, the flights are:
1. Mandarin airline AE392 08:40AM to TSA
2. Mandarin airline AE394 06:50PM to TSA
3. Mandarin airline AE396 09:20PM to TSA
How could one transfer with such flights? TSA-TTT-TSA?? And in such a country, you have 9 airports transferable, compared with Viet nam (4x population, 9x country size), only 2 airports can transfer.
I asked in email support, the answer is similar to that even smallest airport, people may transfer. I could not debate around that. And since the performance for AS server is limited, another argument is even all airports may transfer, we cannot make them all transferable. Then I would say, so it is important to have a algorithm to select airports with most possibilities of transfer PAX.
I would name a dozen of airports which has more transfer possibilities than these Taiwan airports (for example, TYN, 6bars, from Wiki, Annual PAX amount 20x more than TTT). You could name many airports too I think.
The purpose of this post is hear some suggestions about what policies we could suggest AS take when decide if an airport is transferable as long as AS server is not power enough to make all airports transferable.