Explain the causes and symptoms of black-out and red-out.
Black-Out
– Positive G situation where too much blood is drained from the brain and eyes – blackout is loss of vision but not loss of consciousness
Red-Out
– Negative G causes blood to pool under pressure in the brain and eyes – resulting in vision turning red
Explain the effects of positive and negative accelerations on the following
Positive G
Too much blood is drained from the brain towards the abdomen and legs
Leads to:
– loss of consciousness
Negative G
There can be blood congestion problems
Blood has difficulty flowing back to the heart
Leads to:
– Red out (Blood pools in the eyes under pressure)
Positive G
Too much blood is drained from the brain towards the abdomen and legs
Leads to:
– loss of colour vision (greying out)
– blurred vision
Negative G
There can be blood congestion problems
Blood has difficulty flowing back to the heart
Leads to:
– Red out (Blood pools in the eyes under pressure)
Positive G
Ongoing increasing G-force can result in too much blood being drained from the brain into the abdomen and legs, resulting in loss of consciousness (GiLOC).
Describe and explain the effects of the following spatial illusions ...
The ‘leans’ is a strong sensation felt by the pilot, of being in one attitude when the instruments are indicating the aircraft is in a different attitude.
Somatogravic / somatogyral illusion
During a prolonged turning manoeuvre at a constant angular speed’ the middle ear semi-circular canals can only detect the start and the end of the angular motion.
They do not detect the steady state in between.
On recovery from the angular movement, the fluid in the canals is accelerated as the canals themselves stop with respect to the fluid.
The action is then perceived as the start of a rotation in the opposite direction.
This has the effect of the pilot pushing forward to try to ‘level’ the aircraft, which results in a descent into the ground.
Another form of disorientation that can lead to accidents.
The pilot has the ‘leans’ and is not aware of it, and the aircraft has meanwhile entered a spiral dive.
As speed builds the pilot believes he is in a wings level dive and tries to pull out of the dive. There is considerable bank applied and no amount of applied force will pull it up.
The result is the pilot enters into a spiral dive which gets worse by trying to ‘pull the nose level’ and is sometimes referred to as a “graveyard spiral”.
The illusion has to be recognised, the wings levelled and then the aircraft pulled out of the dive.
This effect occurs if you simultaneously induce motion in two of the semicircular canals such as moving head in pitch, when aircraft is rolling.
This is a violent form of vertigo with associated muscle spasms and nausea.
Can be triggered by expanding trapped air in the Eustachian tubes. Nausea and vertigo can result.
The oculo-gyral reflex – the connection between the eyes and the balance organs
When there are problems with this reflex such as an ear infection in the middle ear, this can cause dizziness / loss of balance.
The same can occur when there is a pressure change which causes a popping in the ears and disturbance of the nearby semicircular canals.
Explain the body's limitations in maintaining spatial orientation when vision is adversely affected.
Vision makes up 80% of our spatial orientation. In conditions of ‘white out’ or with no reference to outside, the human brain can become confused and produce false information, affecting the spatial orientation.
Explain the interconnection between the visual and kinaesthetic senses in maintaining accurate spatial orientation.
There is a very strong “reflex” inter-connection between the eyes and the balance organs.
This allows visual tracking of surrounding objects even when the head and body are moving around rapidly or unevenly.
Outline the anatomy and physiology of the motion, orientation and gravitational sensory organs, including ...
These are three fluid filled canals mounted at right angles to each other
They sense angular acceleration in three different planes
They sense individual accelerations
Inside each canal is a water-tight swing door that is deflected by the movement of the fluid
This stimulates nerve endings which send info to the brain
If the accelerating force is too low this will not be picked up by the semi-circular canal
Is the sensory system that provides the leading contribution to the sense of balance and spatial orientation for the purpose of coordinating movement with balance.
Define disorientation.
Disorientation is defined as a condition of having lost one’s sense of direction, or being in a state of confusion
Define spatial orientation.
Spatial orientation is defined as our natural ability to maintain our body orientation and/or posture in relation to the surrounding environment (physical space) at rest and during motion
To tell which way is up
Explain the effects of colds; hay fever; and/or allergies on the sinuses and eustachian tubes.
A blockage of the Eustachian tube caused by a cold, sinus infection etc can cause extreme pain and damage / perforate the ear drum
Explain the effects of pressure changes on the middle ear and eustachian tubes.
The air in the middle ear is maintained at ambient pressure via the Eustachian tube mechanism
This connects the interior of the middle ear to the nasal passage and enables equalising to occur when pressure changes occur in a climb or descent