Great Idea, great quiz, but I guess you have to do some more research. From my personal experience there are at least Tokyo, Bogota, Nairobi and Munich missing (Memmingen is offically Munich-West).
I also can't imagine that that there is no city with two airports in India.
I often wonder about airports with the name of a city that's a long way away - for instance Luton airport is often classed as a London airport, despite being nowhere near it. I'm sure there are similar tales that can be told about quite a few of these.
Perhaps you should make a caveat that this is for the greater metro area. For instance, San Francisco doesn't have 4 airports. But if you include Oakland and San Jose, which are part of the greater metro area that makes 3 airports. I guess Sonoma is the 4th?
Got London, Paris and Moscow, then tried Madrid, Rome, St Petersburg, Kazan, Berlin, Frankfurt, Zurich, Bern, Lausanne, Geneva, Amsterdam, Dublin, Marseille, Lyon, Brussels, Strasbourg, Istanbul and concluded "nah, there can't be any more in Europe" and then found that half of the ones I didn't get were actually in Europe, go figure.
Hi! How about Johannesburg? OR Tambo as main hub, but also Lanseria, Grand central, Rand, Panorama and Tedderfield. Assuming you don't count the heliport?
According to my research, Johannesburg commercial airports are O.R. Tambo and Lanseria. Rand and Grand Central airports are private airports serving civilians (i.e. private jets etc), so those airports cannot be considered commercial airports.
I also can't imagine that that there is no city with two airports in India.
Expecting Rio for Rio de Janeiro would be nice
But really great idea !!
Helipad are not counted.