Certified to fly more than a plane

wrote in message
ups.com...
I'm sure I've come across posts from people here who seem to fly more
than one type of plane at a time, so I guess it's legal in the US to be
able to do so.

Yes (ignoring the humorous misinterpretation possible of your question ).

It's not allowed in my country, and was interested in knowing whether
India alone is archaic or do similar rules exist elsewhere too?

I don't know if they exist elsewhere. But in the US, the only limitation to
how many aircraft in which a pilot can be currently qualified to act as
"pilot in command" is the time required to maintain the currency in each
aircraft. Currency requires a variety of recent experience and training,
depending on the aircraft and pilots have a finite amount of time in which
to accomplish that experience and training, so there is a practical limit,
depending on how much free time the pilot has. But there is no explicit
legal limit in the US.

Pete