Originally Posted by
piratepete
I seem to recall that , like other types, on the 767 the autobrakes will not activate until the pitch attitude is at or less than 1 degree nose up, i.e. you must derotate upon mainwheel touch down.One effect of this is that other inputs, pilot not relaxing the back pressure, spoiler activation, reverser deployment etc etc may cause the pitch attitude to INCREASE or cause a pitch up if the lowering of the nose by the PF is not applied in a timely fashion.Not all FCOMs contain the reference to the 1 degree requirement.Im unsure why that is.
In my outfit's FCOM it is stated that on the 757 autobrake deceleration is limited until the pitch angle is less than one degree. But in the 767 autobrake deceleration is limited until main landing gear truck untilt has occured.
Interesting discussion, I for myself have a few times experienced this pitch up tendency on the 767 but never really got any explanation as to why. I do remember experiencing this on a 737 although rarely but never on a 757. Perhaps something to do with the fact that the 757 column forces required are usually higher?
And on this note interestingly a 757-300 (which apparently has the same speedbrake/spoiler system as 767s) during landing, the nose will drop fast if the speedbrakes are raised too sharply manually. The YSM (yaw damper/stabiliser trim module) which only 757-300s and B767s have apparently is connected to the speedbrake system among other things. And I wonder if that might have anything to do with this, although I believe the 767 does not include the EFL (elevator feel limit) and EFSM (elevator feel shift module) functions of the YSM like the 757-300 does, perhaps that possibly explains the different behaviour.