Hi all,I'm reading through the manuals and came to the section about the ATM I am wondering how to get the temparature for the ATM. Do I just guess it or are there any rules? I have not found anything about which temparature to use in the FCOM nor in the FCTM.If the answer to my question is in one of the manuals please give me the pages in which the answer is provided. RegardsEmi

There are runway performance manuals for that. Usually the airline subscribes to a data provider and the data provider gives the company a book with all of the airports, runways, and T/O weights allowable. Or they provide the data via ACARS or a website. Maybe there's a really complicated "spaghetti chart" in the Boeing manuals, but I've never used it.

I am guessing, but TOPCAT will be able to give a value for ATM, when you input the respective aircraft weight, runway, and weather data... Andrew

Thanks for your answers. I may consider buying TOPCAT now. But isn't there a way I can calculate the temperature myself befor takeoff?

You probably could, but most likely max out at one flight a week should you ever attempt. Seriously, it might be interesting for educational purposes but once you have seen how it's done there is no reason to let this task be done by some specialized tool like it's been mentioned above.