Why does an automatic transmission car roll back when starting on a slope?

[CarmenLynn]

An automatic transmission car may roll back when starting on a slope due to insufficient idle speed. Detailed explanation of why an automatic transmission car rolls back when starting on a slope: If an automatic transmission car rolls back when starting on a slope, or if it stalls when only in D gear without giving throttle on a slope, it is likely because the idle speed is insufficient and cannot propel the car to start on the slope. Precautions for automatic transmission cars rolling back when starting on a slope: If the car rolls back, the only solution is to press the brake, engage the clutch, and restart the car after it has come to a complete stop. Other than this, any attempts to correct the situation during the rollback are generally ineffective.