The claim that the pattern was flown at a constant groundspeed of 497 knots[1] seems to imply no (or little) wind at that place, altitude and time. Is that plau

The claim that the pattern was flown at a constant groundspeed of 497 knots[1] seems to imply no (or little) wind at that place, altitude and time. Is that plausible? [1] This claim appears in Godfrey's original, so it is not a case of the reporter misunderstanding.