When Up Is Down and Right Is Left

There’s a saying that there are two categories of pilots – those who have experienced spatial disorientation, and those who will.

Spatial disorientation occurs when pilots misperceive their position and motion relative to the ground. Essentially, they can’t tell which way is up. What’s more dangerous is that most pilots don’t even realize that they don’t know where gravity is.

It’s not an uncommon occurrence for pilots, especially in poor visibility, and it’s incredibly dangerous. According to the Federal Aviation Administration, between 5 percent and 10 percent of all aviation accidents are caused by spatial disorientation, and of those crashes, 90 percent are fatal.

Draper researchers are working with the University of Colorado – Boulder and NASA to develop spatial disorientation countermeasures.

How We Know Up Is Up

When firmly planted on the ground, it’s easy for humans to know whether they are standing, sitting, or lying face down. That’s because our brains pull information from our visual, vestibular, proprioceptive, and auditory systems to determine our spatial orientation.

• Our eyes help us see a horizon and markers on the ground. Trees, hills, buildings, and ground lights at night all provide visual clues about which way is up.
• Our vestibular system senses linear and angular accelerations, including gravity, and helps us retain balance.
• Our proprioceptive system tells us what position our body is in – are we standing, sitting, arms extended, or otherwise.
• And our auditory system helps us hear and understand sounds around us.

But when our bodies are in unfamiliar, abnormal, or extreme environments, these systems don’t work as intended.

Up in the Air

In flight, the forces on the body change, and our sensory systems can have trouble interpreting what is going on. Let’s first consider this from the perspective of a passenger
on a commercial airplane.

During takeoff, passengers can look out the window and see the plane is moving. They can also feel the plane accelerating and moving forward. At this point, the vestibular and visual senses are not aligned, but our brain is smart enough to figure out what is happening, making things seem fully aligned. It may go unnoticed to passengers but if they weren’t looking out the window, they would feel tilted backwards due to the sustained acceleration.

Once the plane is airborne, things change. Passengers can still look out the window to see the plane is moving, but most no longer feel the plane’s direction of travel, unless it changes. This is because the forces acting on our body stabilize, and our sensory systems are orienting off cues from elsewhere inside the plane. The overhead bins, the floor, and other seats are all stationary in relation to the passenger. Thus, the passenger doesn’t sense movement unless the plane changes speed or banks during a turn, creating a new force on the body.

In fact, if you close the window, you might not even know you’re traveling through the air at hundreds of miles an hour.

In the Clouds

What if you can’t see anything?

What if you don’t have a large cabin with other passengers in which to orient yourself?

And what if you are no longer constrained by the forces of gravity?

These are situations many terrestrial and spaceflight pilots experience.

Nighttime flight as well as clouds or other meteorological events can severely limit what pilots can see. They can create the illusion of false horizons and runway grades.

At the same time, if there are too many forces acting on the body—such as when a plane makes high-speed maneuvers, or a space shuttle re-enters the atmosphere—the brain can misinterpret sensory inputs and struggle to resolve novel sensory stimulation.

This is when pilots can suffer from spatial disorientation and make critical mistakes, including misevaluating the direction a shuttle is flying or miscalculating a plane’s attitude. 

Re-Orienting Pilots and Astronauts

Spatial disorientation, unfortunately, is not a condition that is easily overcome. Even pilots who manage to “recage” and recover safely after experiencing this phenomenon may need to take time to rest and return to normal.

The best remedy is to anticipate when spatial disorientation is likely to happen and to alert pilots, allowing them to take proactive steps to minimize the risk of catastrophic danger.

That’s where Draper comes in.

Draper researchers are working with University of Colorado – Boulder, Langley Research Center (LaRC), and the Disorientation Research Device at the Naval Medical Research Unit – Dayton in support of NASA’s Human Research Program to develop computational models of human perception and disorientation to identify when a pilot is likely experiencing spatial disorientation.

Jordan Dixon, a former Draper Scholar and aerospace engineer, has been working with pilots to understand the situation more clearly from their perspectives. That data, coupled with human-in-the-loop evaluations, is being used to develop human-centered solutions to reduce mishaps resulting from disorientation.

The goal is to engage countermeasures that help pilots realize when they are or are likely to be suffering from spatial disorientation and to assist them in taking appropriate actions for safe flying.

The project, which launched in 2023, is expected to be completed by the end of 2025.