My radio altimeter shows -4 feet, when I am on the ground. Is there something to calibrate it, or is it normal?

The altimeter is biased to indicate gear height above the ground. At initial touch down it will read zero. -4 is due to the strut compression.

The altimeter is biased to indicate gear height above the ground. At initial touch down it will read zero. -4 is due to the strut compression.

Much of the -4 feet is due to the rad alt antenna being forward of the wheels. As the aircraft derotates to zero pitch on ground the antenna is closer to the ground, hence reads negative. 4 feet of strut compression is rather a lot.Kevin Hall.

thank you. I was affraid, that it is not normal behavior of altimeter

The radio altimeter was originally calibrated with the assumption of zero at release of SDK and Tutorial #2. Since then, the earth has shrunk 4 feet due to gravitational compression of time. j/k

I have seen some videos on youtube, where radar altimeter shows "0" when in the ground. So, what should it shows? Is it due to newer and older version of 737NGX, or what?

it could just have to do with how it was calibrated.-stefan

Or a lighter plane. You never know.

it could just have to do with how it was calibrated.-stefan

so, how can I calibrate it?

so, how can I calibrate it?

Install SP1 to "calibrate it"SP1 solved a wrong Rad alt indication on ground.

It's a landing geometry thing. It's designed to read zero as the plane touches down in the flare. The antenna is in front of the main wheels and as the plane goes from 3-5 degrees for the flare to zero, the indication on the RA goes from zero to -4 or -6.Kevin's answer is correct. The old zero indication on the ground was a bug.

ok, thank you

Radio altimeter is close to the Nose LG, just aft of the main avionics bay door. They are 4 squared flat "antennas" 2 are tx, 2 are rx.In the nGX looking at the bottom of the plane they are clearly visible.

Much of the -4 feet is due to the rad alt antenna being forward of the wheels. As the aircraft derotates to zero pitch on ground the antenna is closer to the ground, hence reads negative. 4 feet of strut compression is rather a lot.Kevin Hall.

It's a long strut lol . The strut only extends about a foot on a G5 so what was i thinking lol.It's close to the G5 i flew this morning.Rainy and bumpy on the East coast this morning, Fun approaches. I haven't flown a standard 5 in a while.