@ KKAARR:bro do we count Groundspeed fpr Still air gradient ? ( instead of TAS )
I agree, there is a confusion here..
Its my understanding that gradient will be the same any which way. But if the wind is no longer still, we use the same gradient and GS. TAS can be used only in still air conditions, but in the example, we clearly have 50kts headwind..
Consider we have to clear an obstacle during T/O, and have a authorized gradient for still wind, but have a tailwind component. We cannot calculate the ROC using TAS.
Hence, for the required problem, we would need to use GS.. Its of course debatable.