How do glass panels compute wind vectors?

[MSPAviator]

Ok, I fly standard 6 pack steam gauges 99% of the time.


I got a chance to ride in a Cirrus, glass panel of course. It had synthetic vision and it had a little wind vector arrow that showed which direction and how fast the wind was blowing from.

How exactly does the computer figure that out?

I wish I had one of those in my plane. I still use the E6B for WCA and hand fly everything.

 

[Jim Logajan]

I got a chance to ride in a Cirrus, glass panel of course. It had synthetic vision and it had a little wind vector arrow that showed which direction and how fast the wind was blowing from.

How exactly does the computer figure that out?

It needs to know the direction and magnitude of the ground velocity vector and the true air speed vector. The vector difference between the two is the wind vector.

It may get the ground velocity vector from two or more GPS or VOR/DME readings.

It may get the true air speed vector from the indicated airspeed (pitot) reading, corrected for outside air temperature and altitude setting (barometric pressure.)

That's how I would program it - but I have no idea if that is what those systems actually do - I'm assuming the above is the most likely mechanism.