Turning TCAS off in flight.
I once asked why our company proceedures had changed to leave the transponder on when changing our squawk.
The question was put to me 'What would you prefer to apologise for, squawking the wrong code or bumping into someone?
Unfortunately all the aircraft I have flown require you to select the TCAS off to select STBY.
Turning the TCAS off in flight might not be a good idea.