Situational awareness is critical when you’re on the gauges, right? Few of us will argue that with a good EFIS it’s child’s play to maintain that situational awareness, regardless of the quality of your scan. So far, so good.
But, situational awareness is supplemental to the primary tasks of instrument flying—maintaining course, altitude and airspeed. For that, you need to be constantly cross checking your three primary instruments. It doesn’t matter whether those three are discreet instruments each more than three inches from its closest neighbor, or whether they’re clustered together over a background of a synthetic view of the ground on your primary flight display. You’ve still gotta keep an eye on your heading, your altitude and your airspeed. Of course, including attitude in that scan will help you keep the other parameters in check.
