Manual reference EPR setting B757

[Richard Spandit]

Pulling out the manual EPR knob below the lower EICAS screen causes the reference thrust annunciator to change to "MAN" and the green EPR bug goes to 1.55. In VNAV PTH mode, this does nothing, as one would expect. Pressing "EPR" on the MCP causes the autothrottle to set this manually selected EPR (the vertical navigation changes to V/S). This has caused some trainers at my airline to scratch their heads a bit as they were under the impression that the autothrottle system would not drive to this manually set reference, but it clearly did on a flight the other day where we tried it.

Any pointer? The systems manual is useless (although haven't checked the old, more useful one)

[Jonty]

Originally Posted by Richard Spandit

This has caused some trainers at my airline to scratch their heads a bit as they were under the impression that the autothrottle system would not drive to this manually set reference, but it clearly did on a flight the other day where we tried it.
Any pointer? The systems manual is useless (although haven't checked the old, more useful one)

Dont know why they are confused, you have asked the Auto throttle to set a commanded EPR by pressing the EPR button. By pulling the manual selection knob you have also selected the EPR you would like the auto thrust to set.
Any selection of Autothrust mode or speed mode will cancel Vnav Path (except just opening the speed window on some models). When no pich mode has been selected (ie FLTCHG) VS becomes the default pitch mode.