At 00:40 16 December 2014, wrote:
As previously said - look in the manual and TC for directions from the
manu=
facturer as to what source to use. Usually they will specify a source for
t=
he ASI system as the placard limits are in IAS using those sources. I've
of=
ten found they will specify on for the altimeter too though as UH says it
d=
oesn't matter much for the altimeter. Paul Bickle and Dick Schraeder's
test=
s usually found that the most accurate static sources are ones well aft
on
=
the fuselage sides so those should be used for varios. Static sources on
th=
e multi probe are probably very accurate too. If you have both aft
fuselage=
statics and a multi probe you could use the fuselage ones for the
mechanic=
al vario and the multi probe for the electronic vario so that the two
don't=
suffer from interference.

The last sentence is puzzling. Mechanical glider varios are connected to

the TE line and capacity and have no separate static connection. It is
connectng both an electric and mechanical vario to the same TE line by T
piece close to the instruments that has the potential for pneumatic
interference.