Imagine t/o is on top a cliff or steep large hill (or similar), you t/o and fly down (maybe 500 feet). If you press RTH presumably the P4 rise rise to the occasion and make its way back up to the correct altitude/position and land? In a similar situation if you landed 500 feet below and kept the props running as the recorded t/o point was where you originally took off would t/o again and then return if you pressed RTH?