737NG RA -4?
 

Could someone please explain the logic for the RA indicating -4 while on the ground? It’s hard to find the detailed information these days.

RA is calibrated to read 0 at normal touchdown attitude, not while the aircraft is on the ground

Thank you, I suspected it was something to do with the landing geometry by their location on the airframe. That clears it up.

Further to it, landing gear strut compression also reduces the reading on the ground. During touchdown, it's supposed to read zero when the struts are still not compressed.