Analogue or digital instruments?

[wings folded]

We have two cars, one with an analogue speedo, one with a digital one.

The digital one gives you the impression of greater accuracy but that could be illusory, for if you slow down rather sharply, the readout appears to lag, so you seem to be doing 12 for a moment or two, when in fact already stationary.

The analogue is however a bit less accurate in its graduations, one feels.

I used to fly but never in anything so posh as to have anything remotely digital about it. So for flying, I was used to needles.

My basic question is: What are pilots' views (who have flown under both regimes) on the merits or drawbacks of either system?

Is the brain able to process quicker that the needle points in the expected and familiar direction or close to it, than to process that the number displayed is the desired one or close to it? Or vice versa?

[Callsign Kilo]

With EFIS your scan is more centralised. Everything that I need to fly is set o n a PFD (primary flight display) with the centre of the universe being the AI with my ASI strip to the left and the altitude strip to the right, combined with the IVSI. A great big cross (flight directors) are a helpful tool for us lazy airline pilots. On the same bit of kit I have my LOC and GS (localizer and glideslope) indicators for the ILS. Above the AI an annunciator tells me the mode the autoflight system (vertical and lateral) along with the autothrottle is armed/engaged in.

So its all a central bit of kit which replaces around 6 steam driven gauges. As I say, your scan is more centralised and therefore easier. I would struggle converting back to analogue now. It would take me about 6 months to figure out where the hell my magenta line on the nav display had disappeared to? EFIS is a lazy man's aircraft

[SloppyJoe]

The instruments that would be easier to read fast and interpret with a needle still have a needle on EFIS aircraft. Most engine parameters have a digital needle.

You could argue airspeed would be more instinctive with a needle but I think all the extra, updating automatically, info on airspeed greatly outweighs the benefits of a needle.

[wings folded]

Sloppy and Kilo,

Thanks for your contributions.

Interesting, Sloppy, that engine parameters are given by a needle, albeit digital. I have never needed to manage more than one engine per flight, but I imagine that to see 2,3,4 (or even 6) needles all happily pointing the same way is a piece of info which you grasp in one glance, rather than having to compare that many numbers.

For well known reasons, it has been a while since I visited a "glass" cockpit, but now you mention it, I do recall seeing that (and of course one can always see examples on the good old internet.)

Kilo, I fully take your point about having all your primary data grouped in one place.

Would I be correct in thinking that this aspect is so advantageous that it overrules any other consideration?

I have a feeling that it is a personal matter whether you find digital more intuitive or less than analogue. I recently hired a car which let me display either system, and I found that you could in fact display both, so I did. I found myself nearly always using the needle. I used the digital bit to give an accurate speed check where the dreaded radars were present.

[SloppyJoe]

There is no contest, EFIS is with out a doubt better once you get used to it. There is so much more information and with the systems displays if a parameter is getting towards a limit (advisory) it calls up the relevant page on the display with the value pulsating in green. It really does make life a lot easier but think it can make your scan a bit lazy. It can also make you focus a bit too much on a problem it is displaying or instructions it is asking you to do and in a way suck you into the procedure without seeing the big picture.