A critical review by the leading experts in the field of FLASH presented their answers to critical translational questions towards clinical implementation of FLASH. The authors affirm that FLASH represents the most exciting prospect for increasing the biological therapeutic index of radiotherapy in recent history for that 1) the FLASH effect is robust and reproducible, 2) FLASH effect maintained with fractionation, 3) FLASH effect maintained in combined modality therapy, 4) highly conformal delivery is likely compatible with the FLASH effect, with novel techniques and technologies, and 5) FLASH research is ready to move onto therapeutic clinical trials providing careful trial design and appropriate technological and quality assurance infrastructure. Achieving its potential depends heavily on technological implementation.