I calibrated the OAT on my Rock Mountain Micro Encoder on the ground.  However, I still noticed significant in flight errors, especially in the wintertime.  On a recent flight at 19,000, with a reported OAT of -25c, I was indicating -12c.

 

I spoke to Rocky Mountain, I learned that the body (back) side of the probe needs to be either insulated or in an area where the temperature is near the OAT.  If it is in a heated area like my installation (ie, in the NACA scoop in my 360), the probe will not be accurate.  They suggested that spray on foam insulation of about 1”, or relocating the probe to an unheated area would solve the problem.  It makes sense, I had just never thought of this possibility before.

 

Regards,

Clark Baker

N250JF

LNC2 360 – 550 hrs tt (and still debugging!)