A hard disk drive (HDD) includes a spindle motor, an actuator, a static eccentricity sensor, a monitor and a central controller. The spindle motor includes a rotary body and a static body adapted to support the rotary body, where the spindle motor is adapted to rotate a disk. The actuator is adapted to move a read/write head over the disk. The static eccentricity sensor is adapted to measure static eccentricity associated with the rotary body. The monitor is adapted to monitor the measured static eccentricity and generate a free-fall signal when the monitor determines that the HDD is in a free-fall state. The central controller is adapted to initiate an unloading/parking operation for the read/write head in response to the free-fall signal.