S A F E T Y
denied on the grounds that taking measures to avoid spatial
disorientation was the responsibility of pilots, not ATC crews.
Tactile Situation Awareness System
McGrath’s research into spatial disorientated began
in the 1990s when his study of the vestibular
system led him to create a computer model
that could predict when a pilot would
experience spatial disorientation based
on the flying conditions.
That research led him to Dr Angus
Rupert, a research scientist at the
US Army Aeromedical Research
Laboratory. While McGrath’s model
could diagnose the problem of spatial
disorientation Rupert thought he had
found a solution.
“The idea was very simple,” says
McGrath. “He thought that since we have
these three systems for balance and we lose
two during flight, why not find a way to add one of
“We couldn’t get into the vestibular system – it’s very
deep within our skull – so the easiest one to add back was
the skin-muscle joint system.”
To do this Rupert devised a belt worn around the pilot’s
46 | BU S INE S S A I R P O RT INT E RNAT I ONA L JA N UA RY 2 0 2 0
torso that gives cues about their true orientation. Known
as the Tactile Situation Awareness System (TSAS) the belt
has miniature tactile actuators sewn inside it that vibrate at
different locations and intensities along a pilot’s torso.
The vibrations alert the pilot to irregularities in an
aircraft’s orientation. For example, a plane roll to the right
will trigger an actuator to go off in the pilot’s right side. In
order to do this the belt pulls orientation data directly from
aircraft’s distribution bus.
“The tactile cue on the body is pointing to the centre
of the Earth even though the resultant force on your body
could be pointing in any direction,” says Rupert. “It’s
basically reminding the body where is down.”
The TSAS belt, which Rupert and McGrath are
developing at Embry-Riddle’s Aerospace Physiology Lab,
works so effectively that once it is operating “it’s not even
possible to make pilots spatially disoriented, even if you try”,
This is because the belt interfaces directly with
the skin-muscle joint system, accessing a part of our
cognitive system that responds reflexively without the need
for mental processing.
“Our tactile system is very basic and primeval,” he says.
“It actually sits on top of the brain stem and is how you
got around your mother’s womb - your vision and
vestibular system came online much later
The concept of tactile cueing in
aviation is not anything new, says
McGrath. The stick shaker that warns
pilots of an imminent stall is a form of
tactile cueing, for example. Rupert’s
main innovation has been to locate
the cueing on the torso.
“It turns out the torso of our body is
a very good 3D display,” says McGrath.
Rupert and McGrath are hoping
to eventually produce the TSAS belt
commercially. In the private aviation sphere
Rupert anticipates particular interest from
“That’s the community with the greatest need for
something like this,” says Rupert. “They have a higher
accident rate because they are more often landing at
non-airport locations where the risk is greater.”
The most common types
of spatial disorientation
Over the years researchers have identified several common illusions that spatial
disorientation can cause in pilots.
The Leans – Normally the fluid in the inner ear, which alerts the body to changes
in orientation, starts moving when the body tilts beyond horizontal. But if you
bank too slowly the fluid won’t move, giving the pilot the illusion that they are
flying with wings level. The problem can be compounded if the pilot corrects the
plane’s orientation, meaning the vestibular system will cue the body that it is
leaning when it is in fact upright.
The Coriolis illusion – The Leans are an example of somatogyral illusion, which
means a failure to detect movement or perceiving movement in a different
direction to reality. Another somatogyral illusion comes about when the
pilot executes a constant turn long enough for the fluid in the ears to stop
moving. If they then make the mistake of moving their head suddenly this can
start the fluid moving in an entirely different axis. This will cause the pilot to
Accelerating and decelerating – Besides somatogyral, the other main category
of spatial disorientation is somatogravic illusions. This is the phenomenon of
experiencing sudden speeding up or slowing down as climbing or descending.
Rapid acceleration confuses the vestibular system into thinking you are rising
upwards. In this case disoriented pilots could tip the plane in to a dangerous
nose dive. The inverse is true of rapid deceleration, which could cause a pilot to
climb, suddenly risking a stall.
“It turns out the
torso of our body
is a very good
Dr Braden McGrath, Embry-Riddle
Right: The research team at
Embry-Riddle has investigated
the use of the vibrating vest
to warn pilots about spatial