Full Wings:
If you have access to a 777 FCTM you will find that postive climb is NOT called with reference to the VSI or radalt but solely with reference to the altimeter.
About a third of the people I see in the sim are doing it wrong.
The VSI can and will show positive climb when the gear is on the ground because it is only a measure of acceleration.
The radalt reading is the delayed product of an algorithm and not a direct reading of height. Thus it can and will be tricked by aggressive handling in pitch as one might do in a windshear encounter near the ground.