If you specify a takeoff time for your flight, SkyDemon will make sure it has all forecast information available in that time window. If you don't set a takeoff time, it'll assume you're taking off in the near future.

I can see head/tail is useful, but drift is fairly useful for accurate holding, though I accept one could estimate that from en route heading to make the desired track. SD is also very much for VFR.

Thanks, Chris. Wouldn't a reasonably accurate TAS be relatively simple to input? It might not be simple to calculate, of course.

The wind instrument shows the forecast wind at your current position, altitude and time.

The wind field shows winds aloft when you are flying. In order to compute it from scratch you would need knowledge of your current airspeed as well as a magnetic heading and GPS fix. Since SD doesn't know your airspeed I interpret the winds aloft shown as coming from a forecast value interpolated for your position and displayed relative to your magnetic heading.

-- Chris.

I'm sure this has been answered elsewhere, but I was trying to figure out, when in flight, what the wind field should show (under the vertical column of GS, Track, Alt. etc.) - at the moment all I have is an X (for no data?).