I am a newbie and was given a Phantom SE3 at Christmas.
Last week I flew straight out, 1,500 feet from shore, over open water where we live at Stingray Point, Deltaville, VA on the Chesapeake Bay.
Later I uploaded my flight data to the airdata website and did an analysis of the wind at different elevations.
For the run out, my elevation was 50 feet. For the return home it was 250 feet.
While the wind was calm on shore, a few hundred feet offshore it was not quite at 5 mph. For the return flight back, the wind was almost 11 mph.
As a sailor, it has always been my understanding that, as wind speed doubles, i.e., 5 to 10, the force on the sail increases four times.
It quadruples.
Change facts, assume 5 mph v. 20 mph at the higher RTH elevation.
From 5 to 10, it doubles, from 10 to 20, it doubles again, presumably, an eight time increase in opposing pressure on the AC.
Bottom line, calm winds at ground level do not equal the wind force on your AC body for the RTH if your elevation is up there.
Lesson learned - I now edit my RTH elevation for every flight, to the lowest safest level possible. For so many of the "My drone flew away" posts that I have read, I suspect that the RTH winds exceeded the airspeed ability of the drone to be able to return.