T/O performance - done by a very clever computer somewhere in Scandinavia in response to data entered in ACARS. Waste of time in 757 with one t/o flap setting used and ASTM only. In the 767 with 3 fixed derates and ASTM available as well as a variety of flap settings and improved climb if req, it's invaluable.
It's another of those many functions which needs to know where you are - all part of the INIT function.
Hope this helps
Last edited by deltahotel; 11th Dec 2012 at 08:35.