[Tagging] Airport subtypes

[Elizabeth Dodd]

A recent import has highlighted the lack of suitable subtypes of
airport in the tagging schema.
There are some pages of lapsed concepts on the wiki of different
airport subtypes

A scan through the wikipedia gives me
international airport
domestic airport
regional airport 
airstrip or airfield


Can we put together some ideas and reactivate one of the lapsed
proposals to improve this section of tagging?