For any particular airframe configuration the performance of an aircraft is determined by two factors: attitude and thrust settings. Do the latest EFIS attitude displays include engine thrust so you don't need to look away at the centre instrument panel to see what the engines are doing? (I've been retired 8 years so my tech knowledge is out of date.) Noting the displayed values would enable the pilot to assess likely performance. So pitch x degrees plus thrust y% would yield vertical flight path z.
So, you're driving your 767 down final approach with a pitch attitude of +1 or so. If the N1s are 60-65% you'll be following the GS at Vref plus a bit. If the N1s are not in this range your speed will be wrong. (Figures based on memory.)
Last edited by Discorde; 16th Aug 2016 at 18:36.