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All else being equal, considering the reliability of instruments, human factors, etc., is it safer to fly in a piston-single GA airplane with steam gauges or with a glass cockpit?

In other words, if I want to buy an airplane (hypothetical; I'm definitely not buying an airplane any time soon) and I see two planes that are identical except for the avionics, and safety is the only factor I'm considering in my decision, should I buy the one with a glass cockpit or with steam gauges?

Someone
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    Problem with traditional instruments is, you usually have only one copy of everything because the instrument panel is only so big. With glass cockpit you can spread multiple copies of all the critical sensors across the air frame, wherever the most convenient. – user3528438 Jul 15 '23 at 15:14
  • in https://aviation.stackexchange.com/a/84080/1289 Dean F says "some PFDs like the Dynon Skyview models have the option to switch the displays to instead represent an analog six-pack" – RedGrittyBrick Jul 16 '23 at 10:22

1 Answers1

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With rare exceptions, such as a retired fighter pilot or an ATP leisure flying in their spare time, the weakest link in a GA aircraft is overwhelmingly the pilot.

Most accidents are straight pilot error, followed by engine failure, and it's the lack of flight recorders that keeps us from learning what caused the "unknown" accidents.

Whichever display is easier for you to understand is going to be safer. Even non-certified avionics' failure rates are small compared to pilot failure in reading them.

Everything else equal, such as when learning from scratch, glass cockpits make it easier to avoid trouble. They offer GPS navigation, which is hard to misread, can display maps and traffic information, are easier to read, and sometimes include automated warnings.

That said, for pilots who already have a lifetime's experience of reading traditional gauges, it can be worth more in an emergency than the convenience of digital readouts. High stress can cause mental regression, reverting to the earliest memories of similar situations, and first training with steam gauges will transfer well to any aircraft that has them.

P.S. Technical addendum:

As far back as 1949-1953, there was a series of studies, the first involving 97 military pilots, which proved digital and single-hand dials to perform well, but dials with 2+ hands, required for e.g. altimeters, an ergonomic challenge. This has led to an increase in the use of digital counters, back then mechanical. Moving tape was deemed the best (the last design, "I", doesn't show the value's rate of change).

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Glass cockpits offer a total solution. But they place a lot of information on one screen and expect the pilot to know where to look for what, how to change modes when needed, and what each mode entails. So training and regular practice with the specific PFD (primary flight display) layout used are essential to keep their reading intuitive and automatic.

Figuring out an unfamiliar PFD can take a lot of time the pilot might not have. Steam gauges aren't great, but they share a mostly-consistent design across every aircraft that has them as primary instruments.

Therac
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    This is a great answer. I simply add that a modern glass cockpit has the possibility to improve safety through improved situational awareness. Moving map GPS, traffic identification, real time radar, lightning strike detection, etc. All have the potential to keep a pilot out of trouble. While you could get these features on a kneeboard tablet or other add-on device, I think it is fair to consider their presence in this question. – Rob McDonald Jul 14 '23 at 20:51
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    My main takeaway is the importance of the training to actually use the instruments in simulated emergencies, over the mere technical superiority of the available instruments. Owning the features won't save me on the day when I need them the most. – Jirka Hanika Jul 15 '23 at 20:56
  • @JirkaHanika Agreed. Though I've added a technical part - there really is a significant gain to be had with glass cockpits. As long as one knows how to read and operate theirs by heart. – Therac Jul 15 '23 at 22:07
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    @JirkaHanika adding to that, interacting with the more complex features that a glass cockpit offers without prior training and/or frequent practice may lead to task fixation/cognitive lockup and contribute to loss of situation awareness. More features without training and practice = less safe – DeltaLima Jul 15 '23 at 22:08
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    Is there also the possibility that easier interfaces breed complacency? I know a lot of people who drive manual transmission cars choose to do so because they say they feel more in tune with the machine, or something, whereas a person who simply pushes the pedal to go forward is frequently less aware of how the car actually works. – user253751 Jul 16 '23 at 15:49
  • @user253751 - Read also this. However, I'd infer the opposite causation: the less dedicated pilots choosing the easier interfaces. – Jirka Hanika Jul 17 '23 at 09:25
  • @user253751 There is , but I can't think of many scenarios where a glass cockpit would prompt less cautious flying. Complacency is usually a factor with high-performance aircraft and flying "by the seat of the pants" - ignoring the instruments in favor of "feel". If anything, glass PFD are more "in your face" and likely to reduce this tendency. One possible exception is the Icon A5, which looks much easier to control than it actually is - but that's deliberate design and marketing, and its one glass display is only an optional item. – Therac Jul 17 '23 at 10:11
  • I wonder if a tape display could benefit from having a wheel or two to its right, each with big marks equal to the small marks on the display to its left? If the tape display itself is moving fast enough to be noticeable, the wheel wouldn't be needed, but the wheel would let a pilot quickly judge the direction and rate of change of a measurement even when the tape display appears motionless. – supercat Jul 17 '23 at 16:50
  • @user253751 I'm definitely one of those in the "Save the Manuals!" camp. I do feel more engaged, even when cruising on the interstate in 5th gear. I know that if I need to accelerate hard, I need to drop to 4th, but I do it nearly subconsciously. It also makes me more aware of my speed, since I instinctively hear the engine note dropping up a hill, I know I need to downshift and I'm more aware of the fact that I'm going more slowly. I'd subscribe to the "more involved = more aware" theory, but have no facts or studies to back it up. – FreeMan Jul 17 '23 at 17:40
  • I would think the major gains would be around the avionics providing envelope protection assistance, at the very least. Like a "Banking, sinking" call-out could be game-changer for VFR into IMC stall-spins. Maybe add a settable heading and altitude knob which you set to where you want to be - short of an autopilot, but the system would call out any deviations away from that. – Harper - Reinstate Monica Jul 17 '23 at 18:33