Most general aviation aircraft manufactured today come with "glass cockpits."  Instead of being equipped with mechanical gauges and indicators, they are equipped with computer screens.  The screens integrate and display all sorts of useful flight information.  The information displayed may include satellite weather, synthetic vision, infrared vision, terrain awareness information, traffic

information, and moving maps. Glass cockpits are supposed to help improve the pilot’s "situational awareness." 

Not surprisingly, glass cockpits have been marketed as a safetCirrus Glass Cockpity advantage.  From the website of one manufacturer, Cirrus Aircraft:

We included new safety features to reduce your work load and anxiety by giving you more time to think and improving flight environment manageability. Ultimately, with [our glass cockpit] you get a smoother, more precise flying experience while all the time knowing you are flying smarter, flying safer.

The NTSB agrees that glass cockpits have the potential to improve safety.  But to the surprise of many, the NTSB has now found that, to date, they have not.  To the contrary, aircraft equipped with glass cockpits have a higher than fatal accident rate than comparable aircraft equipped with the old-fashioned, hard-to-decipher mechanical gauges.

Study analyses of aircraft accident and activity data showed a decrease in total accident rates but an increase in fatal accident rates for the selected group of glass cockpit aircraft when compared to similar conventionally equipped aircraft during the study period. Overall, study analyses did not show a significant improvement in safety for the glass cockpit study group.

How can this be?  More information, presented to the pilot in an easy-to-understand fashion, is supposed to be a good thing.  The NTSB’s findings have left many scratching their heads.

I’ve written before that the poor safety record may simply be the result of "Risk Homeostasis" at work.  Risk Homeostasis theory suggests that, when given the opportunity, pilots will use a safety feature to enhance the aircraft’s utility rather than enjoy the increased level of safety the feature could provide.  In other words, pilots use the the glass cockpits to fly into conditions that they would otherwise avoid.  And, instead of painstakingly preparing for the flight before they depart, they prepare "on the fly" (so to speak), relying on the glass cockpit to tell them what they need to know.

A feature – whether it is a glass cockpit or an airframe parachute – can serve as a safety feature or one that enhances an aircraft’s utility.  It can’t do both.

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  • Anonymous

    Your view on glass cockpits is accurate but it doesn’t go far enough.

    First, glass cockpits can actually cause a dramatic loss of situational awareness. As more information is available and displayed in the way of routes, weather systems, conflicting traffic, or pages of frequencies, waypoints etc…there is a marked increase in “head-down” time. Once the head is down, the pilot loses the ability to make accurate”temporal measurements.” Simply, human beings keep track of time by peripheral sight, motion of passing clouds, landscape etc…but lose time when they look down and inside. (This phenomenon is easily tested on subjects asked to estimate passing time after looking down at an instrument…consistently, subjects under report elapsed time)…

    Secondly, there is a well known bell-curve of stress-vs–performance. As stress goes up, performance (flying ability, decision-making etc) goes up too. But only to a point. After that, performance degrades. If stress continues to increase, performane will continue to deteriorate until the stress of task saturation results in panic and confusion. The automation that glass cockpits provide results in low levels of arousal (ie stress) and poor inflight decision-making. Older traditional analogue cockpits kept arousal at a consistent reasonable level. The pilot had to constantly engage in inflight planning, routes, (ie position, time, altitude, next reporting point, estimate) etc. That made for better pilots with higher skill levels, at the period from “top of descent to landing” where accident rates are highest. In-flight decision-making during the period of cruise flight prior to descent was measureably higher. This may account for better performance and the avoidance of task-saturation near the ground. A good example of poor decision-making during periods of cruise-low arousal can be shown by reviewing the American Airlines 1420 crash at Little Rock.

  • Mike Danko

    Interesting insights. The stress-vs-performance bell curve also explains how two pilots can overshoot Minneapolis airport. Unlikely to have happened in an aircraft without all the automation.

  • I have found the discussions of the Cirrus very interesting. In my blog I have pondered why so many Cirrus A/C seem to crash. The combination of too much sophistication, combined with limited basic skills, seems to prove deadly in many instances.

    The article on the NTSB findings on glass cockpits was of special interest.

  • Michiel Schuitemaker

    I love the glass cockpit in my Cirrus. I will tell you though that when you have a power failure that takes out all the displays, you have your hands full. Suddenly, you have to fly the plane and figure out what just happened. Luckily, I use an IPad as well so navigating was not an issue but I can tell you that it is a harrowing experience!!!