737NG RA -4?

[hoss]

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.

[FlyingStone]

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

[hoss]

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

[PilotLZ]

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.