5
$\begingroup$

enter image description here

From YouTube.

I always thought SAT (Static Air Temperature) and OAT (Outside Air Temperature) were the same thing. So does this answer, so does Wikipedia:

[The] outside air temperature (OAT) or static air temperature (SAT) refers to the temperature of the air around an aircraft.

So, what is the difference based on that video capture?

Improve this question
$\endgroup$
2
  • 1
    $\begingroup$ @mins if you want something even more confusing, check my answer below :D $\endgroup$
    – user14897
    Sep 24, 2016 at 4:20
  • 1
    $\begingroup$ Ah, yes now I'm lost and frightened. @Daniel's answer contains a table for COAT (SAT) that corresponds to the more conventional idea (and the difference is smaller). Also this seems interesting: Temperature Measuring Instruments $\endgroup$
    – mins
    Sep 24, 2016 at 4:43

2 Answers 2

Reset to default
5
$\begingroup$

From the manual:

Manual page

So it appears that this instrument's terminology is a little non-standard.

Additional information:

From the Youtube video, you can see that they are moving at a fair pace:

Airspeed

If you take these numbers and plug it into the equations from this question,

$$Ram~Rise=SAT\times0.2\times{M}^2$$

(remembering that SAT needs to be in degrees Kelvin)

You come up with

$$Ram~Rise=(273-33)\times0.2\times{0.491}^2 \approx 11.6C_{rise}$$

Which is pretty close to what you see in the video.

Additional, additional information:

Here is the conversion chart of OAT to SAT in the POH for that (or similar) airplane.

OAT to SAT conversion table

No other qualification is given, but my assumption is that OAT is not TAT, and would be wrong to label it that... it is just the raw temperature sensor value.

Improve this answer
$\endgroup$
1
  • 2
    $\begingroup$ The chart you provided shows no more than 1°C difference. Yet the picture in the question shows a difference of 10°C. What gives? $\endgroup$
    – TomMcW
    Sep 24, 2016 at 19:10
4
$\begingroup$

The manufacturer (Shadin) apparently uses unconventional OEM terminology:

Air Temperature (OAT/TAT): The outside air temperature (OAT, also known as total air temperature) is the reading from the aircraft’s outside air temperature probe. The DigiData provides static air temperature (TAT, or true air temperature) at speeds above 20 knots. Due to the friction between the air and the outside temperature probe, the temperature rise must be subtracted from the OAT. This correction yields the TAT, sometimes called static air temperature (SAT).—Shadin

So their TAT can be True or Total. Both of which the opposite of what we know.

Improve this answer
$\endgroup$
2
  • 2
    $\begingroup$ Except now "TAT" means "true air temperature" not "total air temperature"? lol $\endgroup$
    – Daniel
    Sep 24, 2016 at 4:14
  • 2
    $\begingroup$ Oh man, what's with these people using non-standard terminology? So a pilot sees OAT of -20°C expecting it is corrected for ram rise (which in most aircraft it is). He looks up in his handy chart and makes the proper 710ft altitude correction. Little does he know that the actual/static/true air temp is - 30°C and requires a 950ft adjustment. Let's just hope he has at least a 240ft margin of error to get over that mountain $\endgroup$
    – TomMcW
    Sep 24, 2016 at 19:18

You must log in to answer this question.