ATIS temperature measurement.
ATIS temperature.
I am involved in a little project to increase our payload performance out of some of the more “third” world places that we fly out of.
We leave at a number of places just after the start of nightfall. And we have our doubt about the validity of the ATIS or Tower temperature that is supplied. We think it is a bit high (even a two degrees difference makes a difference of about 1500 kilos, this is a Boeing 777-200). I have looked into how these temperatures come about. The tower temperature at two stations I visited is measured by a big thermometer located (you guessed it, in the tower). The ATIS temperature is measured in one case at least two kilometers away, on top of the building housing the meteorological service. The other is also on top of a building but about one kilometer away.
JAR-OPS Subpart G (performance) 1.490 (c) 2. For take-off performance you should use the ambient temperature at the aerodrome.
My question is:
What are the requirement for measuring an ATIS temperature? At my home base the setup is insane, with over ten temperature probes which are averaged out. At most stations in the less developed world, it is measured at only one place, somewhere on the aerodrome environment. Is there anyone that can supply an answer for me?
Thanks, O.