Too often operators generate SOPs because in isolation they appear to be a good idea. Unfortunately in many modern aircraft with highly integrated systems and displays, situations can be encountered which have not been or cannot be thought through beforehand.
The general recommendation is to follow the manufacturers guidelines or ask if none are apparent.
Very good advice.
However, I think that there must be a degree of latitude allowed, precisely because ‘situations can be encountered which have not been or cannot be thought through beforehand’.
Most guys and gals in my outfit display the Fuel Synoptic when switching off the CTR pumps in our 787s, even though there is no requirement so to do.
There is always a slight ‘frisson’ during the brief period after they have been switched off and before the main pumps have taken over, when there are no ‘green lines’ going to the engines. I guess that illustrates the time delay between sensing and displaying.
Another limitation inherent in such displays is that the ‘flow lines’ in electric, hydraulic, pneumatic and fuel systems generally reflect the position of switches and valves and do not necessarily indicate ‘flow’ within the system. So for the 787 fuel system, the presence of a green flow line indicates that the pump is on and that pressure of 7 to 8 psig is sensed. It does not, in itself, confirm that fuel is actually flowing in the line.
An example where non-display of the synoptic is standard is the Flight Controls display. After engine start, the flight controls are exercised but the synoptic is not displayed, the theory being that any malfunction will be annunciation by EICAS. It could also be that the display may not reflect totally the full movement of all the control surfaces. I remember a similar issue on the 747-400, where the spoiler display only reflected the position of two (non-symmetrical) spoilers in flight. The resultant effect indicated that only one spoiler was actually moving, which was incorrect.
To sum up; I would encourage crews to display and take notice of any information that enhances SA, provided that they are aware of any limitations inherent in that display.