Loiter behavior

Running latest FW. I’m not used to flying in loiter mode. When I tie down my copter and am in LOITER mode, If I raise the throttle the motors speed up as expected. When I lower the throttle to “0” the copter immediately disarms and often reports a crash. I’m worried that the same thing will happen if I’m in the air. I have my throttle failsafe set to 980 and the lowest PWM my controller produces with throttle fully down is 1020.

Is it behaving this way simply because it is tied down? If I lowered the throttle all the way when flying would it descend at a programmed rate and only disarm when it got to the ground? Is there some convenient way to have the copter go UP and DOWN at a fast rate in LOITER mode, yet slow down before landing (like in AUTO mode), so if you wanted to land you could just push the throttle all the way down?

yes, that is the reason