Outside temperature

[Breitling]

The aircraft info window shows a temperature value (suppossed to be OAT or TAT), as well as in the flight label when the windrose window is open. But AFAIK the temperature data is not on the ADS-B frame, so where does this value come from?

[Bethsalem]

On PP's "Help Topics" page there is this

"Important note. The data derived from DF20/21 frames (baro setting, magnetic heading, roll angle, TAS, temperature) is subject to a number of caveats. These messages are elicited from the ground and will only be received in areas of the world where those message types are being requested from the ground radar. The messages themselves do not have any unique identifiers to define their content; the interrogating radar site knows which message was requested, but PP has to guess by applying various confidence checks to the putative content. As such, it is possible for PP to guess the content wrongly and for these values to be spurious. They should be interpreted accordingly. The update rate for these values may be much slower than the other data, so the values may be out of date. In particular, during the descent, it is possible that the aircraft will cease to be covered by the radar that is performing the interrogation of these values and then the values will be frozen at their last figure. The result my be that an aircraft on finals to land, has current ground track and speed but a magnetic heading and TAS lat interrogated on base leg. In this situation, the ground and air vectors will be completely inconsistent and the resulting wind vector calculated by PlanePlotter will be nonsense. Do not be surprised to see improbable wind symbols on aircraft that are close to landing."

[Breitling]

Thanks Bethsalem, I need to learn more about ADS-B and Mode-S...

I've found this document on the net, it is really interesting:

http://www.knmi.nl/bibliotheek/knmipubTR/TR336.pdf

[Bethsalem]

Very interesting that they used a Mode S Beast for this experiment.

[kered]

A good read, i just wonder how long it will be till PP has the option to decode the data and plot the upper weather chart as a GPX overlay, wishfull thinking probably.