So, I have seen some people on the Internet showing the 738's PFD circular gauge for RA, but others show that the gauge is used for AOA(angle of attack). Which one is true? Is there a switch to change the circular PFD gauge between RA and AOA?
$\begingroup$ For readers who may not know, RA is Radio Altimeter: en.wikipedia.org/wiki/Radar_altimeter $\endgroup$– mikeApr 1, 2019 at 18:04
It’s a customer option (i.e. the operator can choose and specify) to switch between the two; presumably by pin programming the computer responsible for generating the display symbols.
$\begingroup$ So there is a switch in the cockpit or it can only be set during the manufacture of the plane? $\endgroup$– lpydawaJan 21, 2019 at 9:18
$\begingroup$ @lpydawa Neither. I’m pretty sure it can be changed during maintenance input (if the option to be allowed to do so has been bought from Boeing for the particular aircraft in question). Maybe someone else can confirm? $\endgroup$ Jan 21, 2019 at 9:20