TCAS does not work if your transponder (or theirs) is off, which is how that collision in Brazil happened. https://en.wikipedia.org/wiki/Gol_Transportes_A%C3%A

TCAS does not work if your transponder (or theirs) is off, which is how that collision in Brazil happened. https://en.wikipedia.org/wiki/Gol_Transportes_A%C3%A9reos_Flight_1907 https://en.wikipedia.org/wiki/Gol_Transportes_A%C3%A9reos_Fl... The Legacy's pilot footrest places the end of your shoes dangerously close to the transponder standby button. https://www.bangaloreaviation.com/wp-content/uploads/2014/04/VT-AOK_Embraer_Legacy_600_DSC_8376_WM.jpg https://www.bangaloreaviation.com/wp-content/uploads/2014/04... The footrest is below the white screen with the navigational chart on it. The radio and transponder panel is the black screen to the right of that, with the yellow and green text on it. The 0512 is your transponder code (squawk); the button to the left of that and down one row turns it off. This resulted in the Legacy losing its TCAS ability, and the 737 it collided with being unable to see the Legacy.