Flights are worldwide every 15 minutes, flown on in a straight line between, and every
few seconds around London. Ships are those that receivers ashore can hear, so few are
mid-ocean or in much of Asia. Satellite positions are worked out from published orbits,
balloons sampled every 5 minutes, trains from the timetable and how late each was last
reported, in Great Britain only. The wind is a weather model’s forecast, not a
measurement. Not for navigating by.