Use of transponder
Hello!
A few questions regarding transponders:
1. After engine start, the transponder is set to STBY until entering the runway, when it is set to ON or ALT as required. What is the reason of setting the transponder to STBY? Why not from OFF to ON/ALT when entering the runway for takeoff?
2. What is the difference between ON & ALT as what I see on the C172 which I fly? Some instructors told me leave it at ON is sufficient, while others prefer ALT. Note that tower does not tell us whether to set transponder ON or ALT, but just gives the squawk code.
3. Upon landing & leaving the runway, transponder is set to STBY, then OFF after engine shutdown. But some instructors say it can be switched OFF immediately upon landing / leaving the runway.
Cheers!