How is a confusion possible between Western and Russian Attitude Indicators?

Question

Yesterday I watched a documentary on Crossair Flight 498 accident. One of the factors that might have contributed to the accident was the confusion of the pilot on interpreting the attitude indicator; he was initially trained with Russian model (right) instead of Western model (left):

But looking at both type of indicators, could anybody tell how the confusion is possible? In both models, if you see the indicators turning your head right (as if you were sat on the plane's seat), both show that the right wing is "touching" ground. That means that you are clearly rolling right. How can a pilot interpret that the plane is rolling left?

Answer 1

It's so easy to sit in our comfy lounge chairs and wonder how on Earth pilots get things wrong.

The error didn't happen without context. It was dark. There was little to no external visual reference due to cloud. The pilots were manually flying in a busy phase of flight. And the captain was probably adversely influenced by a medication/opioid.

Even without the artificial horizon mixup, the conditions were ripe for spatial disorientation.

This image is taken from this short video (yellow arrows were added). It demonstrates how a left turn on the Soviet display is similar to a right turn in a Western display.

The captain was used to the left display, where if the main line of focus was angled to the left, that would mean he needs to make a right control input to go back to wings level. In the accident flight, he saw that the most predominant line - the horizon on the Western display - was angled to the left. Due to the context I've mentioned, he went back to his basic knowledge - that a left angle means I need to make a right control input.

Of course, if he was on top of his game, he would have remembered that even on the Soviet indicator, the artificial horizon should have been level. But by this point he was already disoriented and confused, with the first officer's instructions ambiguous and worsening his dilemma.

Answer 2

The basic premise has been mentioned by everyone above: the basic instinct is to 'right the wrong', and if we see some indication tilted left, we instinctively want to move it right. It's possible to train for everything, but in stressful or confusing situations instincts will take over, it's just a question when.

The reverse ('Russian') indication didn't appear just out of the sense of opposition to the West; it was a product of extensive research. It's been proven that pilots make less mistakes with the reverse indication, from lab tests to the statistics of successful spiral dive recoveries.

Conversely, the direct ('Western') indication is more the result of gradual evolution: early AH had a gyro right in the central ball (or directly connected to it) that represents the horizon, and it naturally kept the 'true' horizon line. (Except that sky and ground were reversed, with the blue or white half at the bottom). And after all, it's just 'obvious' that Artificial Horizon should show, well, horizon!

But there is one more dimension to it. The mental picture of motion is different for different people. Some (apparently, about half or even the majority of) people perceive it better as them being at the origin and the world moving around them. This corresponds to the direct ('Western') indication, and such people must adapt to it more naturally. They also tend to use maps with 'track up' orientation.

Others view (or can easily imagine) themselves from the third person view, and they are more at home with the reverse (and 'north up') display. There was a research (I'd need to find a reference, but it will probably be in Russian) that fighter pilots with this second type of mind perform better in a dogfight.

That said, in a really stressful situation all the complicated mental pictures disintegrate, and the most basic instincts remain...

Answer 3

Just adding few more points to the already existing answers. I agree with previous commenters - some understanding of pilot perception and context is needed.

@Claudix, the image used in your original question can be misleading for 2 reasons:

1. Both instruments are tilted to the right side on your original image. This is, however, not how pilots would see the Attitude Indicator (the instrument itself). Even if the aircraft banks, pilots do not tilt their heads. In fact, in smooth coordinated turn without outside visual clues, you won't notice that your aircraft is actually banking to the side. Your body will sense that you are perfectly level, because at the same time the lift component has been also increased.

2. On a real Western digital Attitude Indicator (display), that little aircraft silhouette in the middle might not be very distinct, as depicted on your original image. It can be also obstructed by Flight Director bars. As Ben pointed out, the most predominant line you might see is the horizon line. The horizon line is what's moving on a Western instrument, and this is what might confuse pilot. In contrast, on the Russian instrument, the aircraft silhouette is moving in front of a static horizon.

To better illustrate your question, I'm attaching this image to show 2 different ways of displaying an aircraft during banking. The upper instrument is the Western display, the bottom one is the "Russian". Both instruments are showing roughly 30 degrees banking to the left, but in two completely different ways.

I'm not a professional pilot on a large glass cockpit aircraft, but I have PPL with some Instrument flight time logged, and find that the "Russian" attitude indicator might be more intuitive and easy to read in some situations.

As an example, if pilot must perform sudden and unexpected upset recovery, to correct the attitude, he might be misled by a very predominant diagonal horizon line on the Western display.

The problem is - it's the horizon line which changed its position in relation to the Western AI display. Consequently, a pilot under stress and / or "tunnel vision" might want to return the horizon line back to it's original position by turning the yoke in the wrong direction, with potentially catastrophic consequences.

Answer 4

(Images from flickr.com and pilotsofamerica.com)

Adding to @Ben's answer, another source of confusion when it comes to human factors is even present within Western attitude indicators. Boeing and Airbus aircraft use the style on the left, whereas Garmin (and mechanical gyros in light aircraft) the style on the right. Note the roll angle and its indicator in a right turn above for both styles. This can add to the confusion when compared with the Russian style.

Answer 5

I think the biggest factor is that under intense stress where the "mental tunnel vision" effect starts to take hold (I've had that experience in the simulator) you revert more and more to your most base line and strongest mental foundations (and if they aren't there you simply freeze). So, while it may seem easy-peasy to adapt to, until the western format has been internalized as deeply as the Russian one, there can be a tendency to start to mentally revert, causing more mental conflict and accelerating the mental tunnel vision effect, ending up in mental freeze mode.

Answer 6

This answer will tackle the question from the perspective of "How might a pilot trained on the Western style of attitude indicator be confused by the Russian style of attitude indicator?" This should also shed some light on the reverse question.

In both of the instruments shown in the question, there is no doubt that brown is showing above the left wingtip of the airplane icon, meaning that the airplane is banked left.

Yet confusion could arise when a pilot used to seeing the Western style artificial horizon, where the moving thing is the horizon not the airplane, assumes the moving on the Russian style is also the horizon, not the airplane.

The exact same source of confusion often arises when a pilot who is used to focusing his attention mainly on the (Western style) attitude indicator tries to fly primarily by reference to the "turn coordinator"- where the moving thing is the airplane, not the horizon. It is very common for relatively inexperienced pilots to react in the "wrong" direction to the turn coordinator, as if the moving thing were the horizon rather than the airplane. This possibility for confusion is one reason among several why many pilots prefer the traditional "turn rate indicator" (aka "turn and slip indicator") to the "turn coordinator"-- despite the fact that by sensing roll as well as yaw, the "turn coordinator" tends to give a stronger indication than the turn rate indicator when an aircraft first starts to roll into an unwanted turn.

And here's a way to take this potential for confusion an even higher level: see this early-generation piezoelectric turn rate indicator manufactured by the Belite company. This product (unlike some later products by the same company which really are turn coordinators with a sensing axis canted away from the vertical to pick up roll as well as yaw) is really just a yaw rate indicator and nothing more. But the way the indicator is meant to be read, is that the illuminated LED lights are meant to depict the wingtips of the aircraft. In a left turn, the lower left and upper right LED lights would be illuminated. This can be confusing to a pilot who assumes that the symbolic airplane (which never moves) is meant to illustrate the airplane, while the LED lights are meant to depict the horizon, after the manner of a Western-style attitude indicator rather than a turn coordinator. To avoid this problem, at least one pilot has found it helpful to completely hide the aircraft symbol behind a picture of a fixed horizon line, with brown earth below and blue sky above, or better yet, to completely hide the airplane symbol behind an abstract symbol designed to suggest that the left and right wingtips of the airplane are moving in an arc with their present position indicated by the LED lights. This helps make it clear that the symbology employed in the device is actually following the same presentation as is employed in the Russian-style artificial horizon, which is also the same presentation as is employed in a "turn coordinator". Despite the confusing fixed illustration of the airplane, the moving thing represents the airplane, not the horizon. Some pilots have felt that a simple arc of LED lights across the top of display representing the movement of the needle of a traditional turn rate indicator, with the airplane symbol completely omitted, would have been a more effective presentation of the information sensed by this instrument.

A comment in closing-- it seems that the Russian style of attitude indicator would be very confusing to interpret at bank angles beyond ninety degrees, where the aircraft is inverted.

Answer 7

I was taught in and flew single and twin Pipers, Beechcraft and Cesnas in the 1980's. All these aircraft had the Russian style FAI, although we referred to them as ground pointers. I'm now flying modern glass cockpits using Western (skypointer) FAI. Although I understand the logic in the Western instrument is better, personally I prefer the Russian style. 10,000 hours later and I still sometimes get tripped up.