(See also notes about airlines and air travel.)
The US makes international transfer passengers go through formalities comparable to immigration. Avoid routings with an international transfer in the US.
Avoid connections through London and Paris airports. Those airports harass passengers by making them go through security even in connections between domestic flights. In Paris this is so inconvenient and slow that I missed a flight as a result.
It is possible that these policies apply to all airports in France and/or England. Nice seems to have the same policy as Paris.
Vienna also makes passengers go through security even in connections between domestic flights.
In Mexico City, terminal 2 makes passengers go through security in domestic connections. Terminal 1 does not. However, the main user of terminal 1 was Mexicana, which has gone bust.
Hong Kong makes (international) transfer passengers go through security checks. So does Jakarta.
Singapore and Kuala Lumpur are convenient for international connections.
Frankfurt, Munich and Schiphol are convenient for domestic connections. I am not sure about international connections.
If you know of any other airports with good policies, or with bad policies, please let me know (email rms at gnu dot org).
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