I am looking into detailed HDD principles of operation and I cannot get my head around this. Slider of the read/write head maintains about 5nm gap between itself and the platter surface using air bearing (basically flying on the cushion of air). I presume this force pushes the slider away from the platter. But in that case, what is the position of the slider when the drive is not spinning (head is parked)? And how it transitions from parked to "flying" above platter without contacting that platter?
The actuator arm is quite thin and I find it hard to believe, there is a 5nm clearance (and manufacturing precision) when heads are moving from parked outside the platter to the platter. I could imagine a situation, where there is a larger gap by default and the slider is "pressed" towards the platter once it is above it and spinning. But of cource the actuator is not spring loaded 😁. It would help though if the air bearing principle was able to keep the slider in constant distance not only by pushing away, but also by "pulling in".
So where is the bug in my presumptions? Is there really a 5nm gap that is maintained in all drive states? Is the air bearing not only pushing slider away?
Related to this, when watching people unstucking the heads, they move the head across stationary platter (sometimes rotating the platter a bit simultaneously). Are the sliders in contact with the platter in that case or not?