EBD. Re the relative positions of the engine gauges in the 737 Potomac crash (blocked Pt2 tubes). It is not quite so simple as that. On the B737-200, the difference between planned N1 (say 95%) and the actual N1 (say 88%), is very little when you see the needles - especially if the cockpit lights are real dim as at night. Same with the fuel flow needles. The N2 needles also show very little visual distance between them.
We set up the anti-ice page on the simulator and select either Pt2 inlet blocked with ice - or sometimes we set up both Pt2 tubes blocked with ice. Very few pilots pick (on the take off run)the lower N1, lower fuel flow or lower N2 - although of course the planned take off EPR is set and clearly visible. All because there is very little angular change of needle reading.
Believe me, one or two fully blocked Pt2 inlets can easily be missed during the engine instrument scan during the take off run. Especially on a dark night with instrument lighting dim. I know - I have seen it happen in the real aircraft, as well as in a simulator. The fix is to set the initial power by using the N1. If the EPR setting is way out, then trust the N1 - not the EPR.