Somotogravic Illusion

[rjtjrt]

I am sure Centaurus knows this but for other Somatogravic Illusion and "the leans" are totally different examples of sensory illusion.
Somatogravic Illusion is a dramatic and life threatening illusion that is very hard to resist, occurring usually around lift off and thus at low level. It can happen to any pilot, not ones that are especially "susceptible".
No one is immune.
When it occurs it will get your attention and you will remember it if you survive.

And Dan (Winterland), the Somatogravic Illusion can be simulated on the ground - it is a relatively/ pretty crude but effective demonstration, in a purpose built but relatively simple simulator. I wouldn't call it a high fidelity demonstration, but very useful.
And yes, I am sure it - I have been in the simulator. It is a crude Link type cockpit that can be pitched/tilted up suddenly. It is probably not a faithfully representation of Somatogravic effect, but enough to teach the sudden almost irresistible urge to pitch the aircraft down when it happens. It makes you respect the power of the urge to push forward on the stick despite being very near the ground ( often/typically a very few hundred feet).

I am now well out of the military medicine aviation medicine loop, so a more recently experienced person may well be able to enlighten us, but, as Centaurus pointed out, talk on page 1 of this thread of "the leans" in the context of Somatogravic Illusion is like talking confusing a Cold with the Plague.

John

[MakeItHappenCaptain]

There is a simulator for Somatogravic illusion, and it is very very persuasive (at least I thought so - 3 out of 3 immediate crashes even though I knew it was coming.
RAAF Aviation medicine have one.

I have one too.
I spin you round half a dozen times (at moderate speed - for a bit of disorientation) in an office chair while you keep your eyes shut, then I accelerate you forwards (keeping your eyes shut) and watch you lean forwards to counter the effect. Everyone I've tried it on so far have done it.

[MALT68]

Just do it all gently! Be mentally prepared!

I am a VFR pilot with a PPL(A) and I also fly gliders. I did my SE NVFR many years ago and was trained by Des O'Driscoll (vale) out at Pinnaroo Airstrip (YPNN). That was a black hole when there was no moon. From very early on I was taught about the somatogravic illusion and the importance the flight work cycle, assess performance, cross check instruments and make SMALL adjustments as necessary. Be gentle!
Have your eyes night adjusted too, that always helps!
Have the a/c set up, have take-off trim set, flaps as required. That is, on take off roll, I steer the a/c down the runway using the runway lights as my guide. As I accelerate through rotation airspeed I know that I will most probably lose sight of the runway lights. Cross check that I have a positive rate of climb with the VSI up, altimeter going up, ASI showing a constant speed, engine RPMs constant and not getting louder or softer, crosscheck nose up attitude on AH. Get the landing light off once stabilised in the climb. On a black night there is not much to see outside on climbout!
Also be familiar with the 'feel' of your a/c in different modes of flight. That is the control feel, the sounds of the engine etc.
This is why I like hand flying the a/c, since many autopilots in light GA aircraft are not very good (they hunt and rove) and actually make for a more uncomfortable ride at night!
When preparing for flying at night, I mentally rehearsed the flight, the places to divert to as well as keeping note of the weather for 'go/no-go' decisions. Make sure that the a/c if set up for flight at night and don't go if minimum equipment standards can't be met.
I have also done circuits into other 'black holes' like Kingscote, Maitland on the Yorke Peninsula, Port Pirie.
I have also experienced the leans over the Gulf of St. Vincent on a moonless night (look at the instruments).
I believe that awareness of the somatogravic illusion and flying with an experienced instructor a dark night sites are vital in reducing this type of accident.
Safe flying and have fun
MALT

[Cravenmorehead]

Air Niugini ask about Somatagravic illusion in their test at their initial interview, in the written test.
It is included in the ATPL human factors course, and I bought a book The Human Being Pilot as a result of discussion with a smart young FO some time back.
I recommend this book to all pilots. When I did my Senior Commercial studies way back when Jesus played full back for Jerusalem-1982, we studied none of this stuff. I think knowledge is power and may just save your life.
This has been one of the more relevant threads on pprune
I personally have nearly covered the current ATPL syllabus.
But I am a nerd, you have to keep up with the young clever whipper snappers, plus it keeps my mind working.
Craven

[Wally Mk2]

'crave' yr comment "knowledge is power" is something that I have lived by as a pilot since I was told that whilst learning to fly & to some degree the same goes with most things in life.

An Aeroplane will fly with just enuf power same goes for it's operator, have just enuf knowledge to fly, the two are balanced/aligned when everything is going swell............'till more 'power' is needed then the brain often runs out of power.
The plane I fly these days you can never have enuf 'power' brain wise but I like to think I have some brain power in reserve for those days when it's not all swell

You carry reserve fuel & for good reasons.
You carry sustenance especially on remote flights & for good reason.
You SHOULD carry reserve knowledge for no other reason than being clever:-).

I've said it b4 in other threads, know yr plane know more than you need just to stay airborne.

"Knowledge is Power"...................never 4get that I say!


Wmk2

[APMR]

I wonder therefore, if some pilots for some unknown physiogical reason, simply are not susceptable to somatogravic illusion on take off ...

I have been a remote-based aeromedical pilot for 7 years now. I would have made near on 1,000 night takeoffs over that time, with the vast majority being from dark, "black hole" locations.

I have never experienced the somatogravic illusion.

I cannot ever recall an experience of "the leans" either, so I would be in agreement with Centaurus' assertion that susceptibility varies between individuals.

I have almost killed myself on a night takeoff, however, whilst taking off in a piston twin from Ceduna towards the east one night in 2004. I got airborne ok, but over the next 10-15 seconds managed to get down very close to the ground.

To this day I have no idea how close to the ground I came, but had every indication that it must have been very close.

Due to the absence of the pitch-up sensation, I believe it must have been poor technique that was responsible for my predicament (I recall looking over the nose at the runway lights as they passed from view).

[framer]

Interesting close call there. What do you mean by poor technique? Did you get distracted away from the instruments ?

[avconnection]

I'd be very surprised if any pilot has never been under the effect of sensory illusion however mild. Some might be slightly less susceptible than others but flying is still unnatural; your body will not understand the convoluted sensory messages it receives. There is a big difference between ignoring sensation through preparation and experience, and not getting the sensations. Unless you're body is different to everyone else's. The sensation that creates illusions don't have to be pronounced for you to be under their effect. How many of you have been filling out a deck log, planning a diversion, while hand flying and look up to see you're in a gentle turn? The difference between you and someone who ends up in a spiral dive is focus and discipline (to maintain a scan while completing other tasks).

The real take home message is not to be fooled by your ability and experience; your body is still receiving sensory messages contrary to your position and it only takes a little bit of inattention (fatigue) to fall over. If this was not the case you could fly with your eyes closed (yet to meet anyone who can last more than 30-45seconds).

I don't think the sensations themselves can be trained for, training for the circumstances and overcoming them, or ignoring your senses through focus and discipline, can be. If you do suffer them for what ever reason, "Reseting" your vestibular system can be as simple as tilting your head back and shaking back and forth (wont work for all).

[MALT68]

Be careful about vertigo with that one!

If you do suffer them for what ever reason, "Reseting" your vestibular system can be as simple as tilting your head back and shaking back and forth (wont work for all).

That is likely to cause disorientation, especially if you are in turning flight. Because such an action will set up fluid circulation in you semi-circular canals (your balance organs).

Try this experiment; sit on an office swivel chair with eyes shut but head still, get someone else to spin it around, stop it open eyes and stand up, you will be dizzy.

Now, on chair, eyes shut, spinning around, nod your head up and down, now stop, open eyes and stand up, you will be evry dizzy.

Always be careful nodding head up and down in turning flight when you are looking at charts to instrument panel to outside. This can make some people quite dizzy.

[avconnection]

The idea is that it creates such a confusion in the vestibular system, your brian relies less on its input and focuses on other feeds, ie, sight. By reducing your sensory input or reliance you can refocus using the AH as a datum. Works for me and a few others I know but not all.

[MALT68]

Try on the ground first...

The idea is that it creates such a confusion in the vestibular system, your brian relies less on its input and focuses on other feeds, ie, sight.

Interesting, you are certainly lucky if you can get away with that one.

For the rest of us, best try that one on the ground first before using it in anger in the air!
(Everyone get out your swivelling office chairs and start spinning and nodding your heads with eyes shut!)

Vestibular dysfunction is usually quite incapacitating. Just talk to anyone has has suffered Meniere's disease.

Fly safely, have fun

Malt

[JustJoinedToSearch]

During my first instrument training flight (at about 8 hours TT or something) before we started my instructor told me to close my eyes and then through a combination of slow undetectable roll/pitch changes and normal maneuvering had my inner ear convinced we were rolled left/nose low until I opened my eyes and saw we were rolled right/nose high.

Takes all of 1 minute and is teaches you very quickly how easily your senses can become disorientated.

[Centaurus]

How many of you have been filling out a deck log, planning a diversion, while hand flying and look up to see you're in a gentle turn

Probably happens a lot. For example when driving a car day or night and your attention is distracted causing you to look away from the road for a few seconds and sure enough the car will soon wander off. You look up and get a shock. Same thing in an aeroplane where you squint and look more closely down at a chart or fiddle a GPS knob and it only takes a few seconds of inattention for the aircraft to take up a gentle angle of bank or height loss. That is not caused by a sensory problem but momentary inattention to the task of hand flying.