Question on transponder / MH370

[Aperture]

Hi everyone,

After watching an interesting video on the MH370 flight that disappeared, I have a simple general question.

1) When the transponder on the XPNDR/TCAS panel is set to STBY, does it mean ATC can't see you on his screen and you fly undetected, the only way to detect you being primary radar pulses ? Or you can still be detected but without altitude, speed etc...
2) It leads to my second question regarding flight MH370: did the flight do what I said in 1), or did they do other things to remain undetected, like tripping CB's, or disconnecting from ACARS ?

Thank you for your answers

[captain.ronin]

Originally Posted by Aperture

Hi everyone,

After watching an interesting video on the MH370 flight that disappeared, I have a simple general question.

1) When the transponder on the XPNDR/TCAS panel is set to STBY, does it mean ATC can't see you on his screen and you fly undetected, the only way to detect you being primary radar pulses ? Or you can still be detected but without altitude, speed etc...
2) It leads to my second question regarding flight MH370: did the flight do what I said in 1), or did they do other things to remain undetected, like tripping CB's, or disconnecting from ACARS ?

Thank you for your answers

From my understanding setting the transponder to STBY prevents operation of the transponder so the aircraft would only visible on the primary radar. It’s speculation but it seems like other systems were also deactivated like company acars.