We also do both at our airport here in the US. We also
have a winch captain or you might know them as GOD
(Glider Operations Director). It's the same as Del
writes below.
Sam

At 05:42 29 December 2007, Del C wrote:
Why not? Many European clubs offer both winch and aerotow
launches, including my own. Some members only ever
aerotow and some (usually the less well off) only winch
launch. Most members do both, depending on the conditions,
what they can afford, and what they want to do. A winch
launch costs less than a third of the cost of an aerotow,
so it is a cheap way of staying current during the
winter when it is rarely thermic in the UK. About
two-thirds of our launches are on the winch, so we
can make do with fewer tug aircraft than would be the
case if we were an all aerotow operation.

The only safety issue is to make sure that aerotows
and winch launches don't happen at the same time, to
eliminate the risk of the tug flying into the winch
cable. We have a 'launch point controller' to make
sure that this is the case.

Del Copeland

At 03:42 29 December 2007, Mike Schumann wrote:

snip
In order to be a safe and successful with winch launching,
you need to make
a 100% commitment. You can't run winches and tows
in parallel, if people
are going to get and stay proficient in winch launching.
In addition, the
only way winches are economically justifiable is if
you totally eliminate
the overhead, operating, and maintenance costs associated
with a tow plane.