Aaahhh, Mutt, mate !! - don't be like that !! .... or are you trying to shame me into pulling out a Flight Manual from time to time to quantify my waffly qualitative statements ?
Actually, the monkey comment does bring up some valid points -
(a) the easy bit IS punching out the numbers - very easy with a Jesus Box and a tad slower using the 4000 pages of the Flight Manual. Those (many) of you who have sweated and slogged through Performance A will know just what the latter comment signifies. However, the "easy bit" statement still stands.
(b) the hard yakka bit is acquiring and verifying obstacle data, escape route flight paths, and so on - an absolute pain in the neck slog type exercise. If you don't do this (or someone else doesn't do it to the required standard on your behalf) then (a) results in "garbage in - garbage out".
I can recall a colleague telling me some years ago of a particular airline which routinely departed with far greater payloads than its competitors (he flew for the airline at the time). Turns out that they didn't bother at all with the obstacles, got the manufacturer to do the number crunching based on the runway length data only. So long as an engine didn't quit - no problems.
(c) where the operations engineer comes into his own is in the sensible and efficient matching of (a) to (b)
Mutt's example with the big bird is quite illustrative - but don't panic too much straight away. During the 400 feet (above runway level) cook's tour of the surrounding countryside, keep in mind that the altimeter approximates the gross flight path while the obstacle profile relates to the net flight path. As a result, critical third segment obstacles are in the vicinity of 150 feet below a twin engined aircraft in a minimum level off height WAT-limited situation.
Hence my oft espoused view that pilots need to know about these things so that they can make informed operational decisions - but you are far better off using a good ops engineer to give you the base data upon which to make your informed operational decisions.
Am I forgiven, Mutt ?
[ 11 July 2001: Message edited by: john_tullamarine ]