Nov 25, 2022

Pilots must combine their human abilities, flying experience and skills, and their flight’s purpose in order to carry out their job. Under this somewhat complex combination of conditions, pilots will inevitably encounter challenging situations at times, including some that may affect the overall safety of their flight. Unfortunately, sometimes, no amount of training or experience can overcome the likelihood of some of these challenges occurring. The Black Hole Effect is one such challenge.

Pilot Spatial Disorientation

As humans, it is fairly obvious we weren’t designed to be travelling at high speeds thousands of feet in the air, our ability to fly is only thanks to some pretty impressive mechanical engineering and flight technologies. Therefore, it comes as no surprise that our human senses – touch, sight, hearing, smell, and taste – are not naturally optimised for the inflight environment. This natural incompatibility means we are all at a significant disadvantage when it comes to operating in the high altitude, high-speed environments experienced during flight.

This disadvantage can sometimes result in spatial disorientation during flight. The topic of Spatial Disorientation covers many aspects of sensory mismatch, but put simply, for pilots, it is a loss of perspective resulting in misjudgment of the situation that may cause loss of aircraft control. A typical example of pilot spatial disorientation is the phenomenon of visual illusions or conflict between exactly what the eye is seeing and what the brain is telling us it’s seeing.

Seeing Is Not Believing!

To better understand these visual illusions and associated disorientation experienced during flight it is necessary to delve into the connection between the eye and the brain. The key to this association is that your eyes don’t do the seeing – your brain does.

The eye’s retina transmits electrical pulses to the brain, which then works to make sense of it all by interpreting what you are “seeing”. It is this interpretation that allows for illusion and disorientation to occur, as the brain’s perception of what you are seeing can be significantly influenced by a number of factors. This includes the setting in which it is viewed, the colours and their brightness (or lack of), the existence or nonexistence of surrounding objects, and the brain’s preconceived notion of what it should be seeing. An excellent example of this is when we perceive dimmer objects to be farther away than brighter ones, even when this may not actually be the case.

It is a well-recognised fact that flying at night is more dangerous than flying during the day, this is largely due to the fact that our eyes are not designed to see well in low levels of light. The reason for this is because at night, the eye relies on the ‘rod cells’ in the retina to do most of the work since they are more sensitive to weak lighting.

Unfortunately, these rod cells see only in black, white, and grey colourings and since much of our perceptive abilities with regard to size and distance are based on colour variation – well, you get the picture! For example, this kind of colour distortion for pilots means certain kinds of terrain and cloud formations can be almost impossible to see at night, and ground lighting might be mistaken for stars, etc.

What Is A Black Hole Approach?

The Black Hole Effect or Approach as it is sometimes known, is a visual illusion that happens when flying at night when only the runway is visible to pilots on approach. This illusion is exacerbated by the absence of any visible ground references or lighting during the approach to land (commonly due to a large body of water or barren land that lays between the aircraft and the airfield) and without the presence of additional light from the moon or stars.

As a result of the Black Hole illusion, pilots tend to overestimate their descent angle, which makes them think they are flying higher than they really are. This causes the pilot to compensate by reducing altitude which ultimately leads to dangerously low approaches (and crashing into the ground) before reaching the runway.

Contributing Factors

Over the years, the Black Hole Effect has claimed the lives of many pilots – both novice and experienced. The exact cause of this visual phenomenon is due to the combination of a number of factors, but it ultimately occurs as a result of our human senses misinterpreting the situation.

The fundamental risk lies in our visual abilities, or lack thereof, where an altered perception means objects can appear further away (or closer) than they actually are. However, there are some contributing factors that increase the likelihood of the Black Hole Effect occurring. These include:

  • Long straight-in approaches
  • Lack of moonlight or visible stars
  • Large bodies of water preceding the runway
  • Featureless terrain preceding or surrounding the runway
  • Reduced visibility due to low cloud, fog or precipitation
  • Brightly lit city lights near the runway (the brightness of the lights gives the perception that they are closer than they are)
  • A clear night with excellent visibility (When the air is extremely clear, the lack of hazing gives the perception that things are much closer than they really are)
  • Wind or turbulence on approach
  • Specific airport and runway hazards

How To Avoid The Black Hole Effect?

While many visual illusions during flight can be overcome with the use of on-board instrumentation, the Black Hole Effect is a little different in that a glance at the flight instruments can’t always be relied upon to indicate the level of danger, at least not until it’s too late anyway. A quick glance at the Attitude Indicator, Airspeed Indicator or Altimeter is unlikely to immediately alert you to anything suspicious. Studying the Vertical Speed Indicator should indicate a larger than normal rate of descent, but this alone this may not immediately raise a big enough red flag.

Because the Black Hole Effect is a combination of what the eye sees and how the brain interprets that, effectively leaving this phenomenon in a no-man’s-land between physiology and psychology, the only real defence you have against the Black Hole Effect is awareness and avoidance. Thoroughly familiarising yourself with the airfield is a must, including extensive pre-approach planning and preparation, here are a few things to consider when trying to avoid the Black Hole Effect.

  • What type of terrain exists on the approach and surrounding the airfield?
  • What runway lighting is available? Are there any approach lights?
  • Is the runway a standard width? Or is it broader/narrower than you are used to?
  • Is the runway level? Or is it sloping up or down?
  • Are there navigational aids (such as Distance Measuring Equipment) that can help determine the position of the aircraft on approach?
  • Are there visual approach path guidance systems available? (Visual Approach Slope Indicator Systems (VASIS) or Precision Approach Path Indicators (PAPI))

Interested in learning more about the human factors of aviation? Take a look at our posts on Airmanship, Cognitive Bias and the Importance of Situational Awareness.

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