Rotor Concept HPQ1 Quadcopter PNP In case of RC signal not being detected during flight, the aircraft will enter the security protection mode (SPM) During power up, if your radio throttle stick is not in the lowest position (zero throttle), The SPM will be activated. Low battery protection Upon detecting low battery, the aircraft will beeb intermittently while still flying. If this warning is ignored, the aircraft wll slowly power down and self land. You still have flight control during this time, but not throttle control.