I personally believe it has something to do with the CG of the 767 and the take off trim setting given by the FMC. The FMC in the 757 will give me a T/O trim setting of something like 2.58 for a CG of 36% whereas the 767 will give me a T/O trim setting of only 0.5 for a CG of 36%. I have found that if I leave the trim setting at the position it was in when the flight was started (0.0 according to the Cockpit Tool Tip on the trim lever) then it will take off, but it is still at about V^r +10 or +15 knots. If I set it at 0.5, according to the Cockpit Tool Tip, it will still take off at about V^r +10 - 15knots but it will climb very steeply (~4500 - 5000 fpm).

Is something wrong with the T/O trim setting from the 767 FMC? Possibly. I watch the magenta box on the left side of the ASI that is the guide for the pitch of the plane and pull up when it reaches the centre and then rises above the artificial horizon.

Hope this helps.

Mark

I'll try both 27, and 36 on my next couple of flights and see what happens. Thanks for the advice.

DAL191 wrote on Aug 1^st, 2010 at 5:11pm:

If I use aussies's method I usually get a setting of between 37-39% (never had it as high as 40% or higher). I have only ever had (as far as I know) a setting of 1.5% - 2.0% ANU and again never a negative number. It is possible that I have misread it though. And I've never had that EICAS warning.

27% sounds right compared to aussie's 37%+.

I shall look into it again. You have made me curious about whether I have been "getting it  wrong".

Mark