Why no power indication on an airliner primary flight display?

Aircraft performance is a function of attitude (pitch and bank) and power. So you’d think that, in an ideal world, these two items would be displayed prominently right in front of each pilot.

This wasn’t possible in the old days because each item was presented on a different instrument. Thus the Boeing B-17 or B-29 cockpit with attitude indicators in front of each pilot and some engine gauges in the middle.

Why not combine this information and summarize it today on the “glass” (LCD) panels that are in front of today’s pilots?

Who does this right? Cirrus! The Perspective system that they co-designed with Garmin for the latest SR20 and SR22 airplanes show percent power at the top left of the primary flight display (regular G1000 does not have this). It isn’t perfect because a lot of space is wasted, e.g., “65% Power” has information only in 2 out of 9 characters, since the “% Power” never varies. I would rather see “65 CRUISE”, “95 CLIMB”, “25 DESCEND”, and “15 APPROACH”.

Who gets this wrong? Boeing, I think. People have wondered why the pilots of the latest B737 MAX to crash didn’t pull the climb power out. One possible reason is that nowhere on the primary flight display (PFD) images that I’ve been able to find is power indicated:

Power is displayed in the Boeing B-17/B-29 location: in the center of the panel (dashboard).

It fascinates me that decades after the obvious user interface became easy to implement (microprocessors have to paint the pixels, so why not put in the information that matters?) we still don’t have the obvious user interface.

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8 thoughts on “Why no power indication on an airliner primary flight display?

  1. Since analog gauges are easier to read than digital, instead of the “xx% Power” text in the upper left why not put in a small circular gauge (in the mostly unused upper left corner of the PFD) that would have a sweep hand to show the power percentage, along with a digital number in the center of it, much like the visual representation used for tach/manifold pressure on a lot of digital engine monitors?

    If that would be too likely to be confusing with the attitude indicator, then a vertical tape on the left side would also work. 0% at the bottom, 100% at the top, and a color change with digital readout to show the actual value.

  2. I wonder if the difference in ergonometric quality is because Cirrus aircraft are purchased by the people who actually pilot them, whereas the Boeing airliners are purchased by executives who likely have never piloted an airplane.

    • J. Peterson, wrong! Most airline executives have piloted airplanes and have whole departments that study “ergonometric qualities”. The boeing displays are much simpler and efficient. Airliners are never flown VFR so there is no need to have all the clutter of synthetic vision and what now.

    • J. Peterson, wrong! Most airline executives have piloted airplanes and have whole departments that study “ergonometric qualities”. The boeing displays are much simpler and efficient. Airliners are never flown VFR so there is no need to have all the clutter of synthetic vision and what now.

    • While it is technically true that airliners aren’t flown under VFR it’s mostly because of regulations prohibiting VFR in Class A airspace (above 18000ft MSL in US), not because they aren’t flown visually. In fact, with ADS-B and Free Flight initiatives the IFR will essentially merge with VFR: the main difference between watching out of windshield or at the same picture on the glass panel is that on the panel the relevant stuff is clearly marked and very visible. In fact, when flying VFR I’m looking more and more at the screens, especially in high-traffic areas – I certainly see a lot more traffic on the map than out of the window. VR headsets will also help to deal with limited visibility out of cockpit and will integrate visual, IR, and synthetic vision, like they do now on advanced fighter jets.

      (When I fly a drone I already use a commercial FPV VR headset… works nicely as long as signal is good:)

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