"Gregg Germain" wrote

Is that always the case? Or even usually? For example, I fly out of
Hanscom
and Beverly fields in Massachusetts. Beverly is pretty small - couple of
5000+ foot runways. Still, we get pax carrying planes in and out of
there -
small jets, 10-20 pax prop planes etc. So it's commercial. And therefore
need to operate in IMC, and therefore you need a tower, no?

No, you don't need a tower in order to have instrument approaches at an
airport.

So could the existence of passenger service be a reason there are Class
D's
around?

I think it has to do with traffic density more than anything else, and yet
there are some pretty busy airports that are uncontrolled. A airport near
where I fly has an ILS and an NDB approach as well as a high density of both
piston and jet traffic, and it was uncontrolled up until about a year or so
ago. It used to be that you needed a shoe horn to get into the pattern on
any decent VFR day.

BDS